Recognition memory and response bias in elderly demented, depressed, and demented/depressed patients

R e c o g n i t i o n M e m o r y a n d R e s p o n s e B i a s in E l d e r l y Demented, D e p ressed, a n d D e m e n t e d / D e p r e s s e d P a t i e n t s by M o n i c a M a r y M c Q u a i d B . A , , B o s t o n College, 1985 M.A., U n i v e r s i t y of v i c t o r i a , 1988 A D i s s e r t a t i o n s u b m i t t e d in p a r t i a l F u l f i l l m e n t of the R e q u i r e m e n t s for t h e D e g r e e of

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af-M t I'Y OF CjHAHUAI'L. U iU tilF S

' in t h e D e p a r t m e n t of P s y c h o l o g y We a c c e p t this t h e s i s as c o n f o r m i n g r , ) A " J lA to t h e r e q u i r e d s t a n d a r d o t f r i e d Spreen, Ph.D., S u p e r v i s o r D e p a r t m e n t of P s y c h o l o g y - V — --- >•-— ---Pam Duncan, Ph.D., D e p a r t m e n t a l M e m b e r D e p a r t m e n t of P s y c h o l o g y M i c h a e l Joschko, P h . D . , D e p a r t m e n t a l M e m b e r D e p a r t m e n t of P s y c h o l o g y C. B r i a n HarVey-P* Ph.D. , O u t s i d e M e m b e r D e p a r t m e n t of P s y c h o l o g i c a l F o u n d a t i o n s in E d u c a t i o n H o l l y A. Tuokko, Ph.D., E x t e r n a l E x a m i n e r

C l i n i c for A l z h e i m e r ' s D i s e a s e and R e l a t e d D i s o rders, U n i v e r s i t y of B r i t i s h C o l u m b i a © M O H I C A M A R Y MCQUAID, 1993 U n i v e r s i t y of V i c t o r i a A l l r i g h t s reserved. D i s s e r t a t i o n m a y n o t be r e p r o d u c e d in W h o l e o r in part, b y p h o t o c o p y i n g or o t h e r m e a n s , w i t h o u t t h e p e r m i s s i o n of t h e author.

Su p e r v i s o r : Q t f r i e d Spresn, Ph.D. A B S T R A C T E l d e r l y d e p r e s s e d p a t i e n t s are o f t e n r e f e r r e d f o r a n e u r o p s y c h o l o g i c a l e x a m i n a t i o n to e v a l u a t e t h e i r c o g n i t i v e a b i l i t i e s and to a s s i s t in m a k i n g a d i f f e r e n t i a l d i a g n o s i s o f d e m e n t i a vs. d e p r e s s i o n w h e n the e t i o l o g y of p r e s e n t i n g s y m p t o m s is unclear. I n d ices of d i s c r i m i n a t i o n (i.e., the a b i l i t y to i d e n t i f y t a r g e t f r o m d i s t r a c t o r i t e m s d u r i n g r e c o g n i t i o n m e m o r y testing) a n d r e s p o n s e b i a s (i.e., t h e p r o b a b i l i t y of s a y i n g ''yes" t o an i t e m w h e n u n c e r t a i n if it is a t a r g e t or a distractor) h a v e b e e n s u g g e s t e d as u s e f u l a i d s w h e n m a k i n g su c h a d i f f e r e n t i a l d i a g n o s i s . P r i o r r e s e a r c h i n d i c a t e d t h a t d i s c r i m i n a t i o n a b i l i t i e s w e r e s i g n i f i c a n t l y b e t t e r in d e p r e s s e d e l d e r l y as c o m p a r e d to d e m e n t e d e l d e r l y a n d t h a t d e p r e s s e d p a t i e n t s u s e d t h e m o s t c o n s e r v a t i v e r e s p o n s e s t r a t e g y (i.e., t h e y t e n d e d t o say •'no*' m o r e o f t e n w h e n uncertain) w h i l e d e m e n t e d p a t i e n t s h a d a m o r e l i b e r a l r e s p o n s e s tyle (i.e., t h e y t e n d e d t o say "yes" m o r e o f t e n ) . However, li t t l e is k n o w n a b o u t t h e p e r f o r m a n c e of p a t i e n t s with d e m e n t i a c o m p l i c a t e d b y de pression. T h i s s t u d y a t t e m p t e d to a d d r e s s t h e n a t u r e of d i s c r i m i n a t i o n a b i l i t y and r e s p o n s e b i a s in p a t i e n t s w i t h d e m e n t i a c o m p l i c a t e d by depression,, as c o m p a r e d to d e m e n t e d p a t i e n t s w i t h o u t a f f e c t i v e s y m p t o m s and d e p r e s s e d p a t i e n t s w i t h o u t c o g n i t i v e impairment. R e s u l t s i n d i c a t e d t h a t

Ill

d i s c r i m i n a t i o n a b i l i t i e s t h a n the d e p r e s s e d group. D i s c r i m i n a t i o n a b i l i t i e s of the d e m e n t e d and the d e m e n t e d / d e p r e s s e d g r o u p s w e r e similar. P a t t e r n of r es p o n s e s , however, r e f l e c t e d a s i g n i f i c a n t l y m o r e c o n s e r v a t i v e r e s p o n s e bi a s in t h e d e m e n t e d / d e p r e s s e d g r o u p as c o m p a r e d to t h e d e m e n t e d group. T h e d e m e n t e d / d e p r e s s e d g r o u p w e r e also m o r e c o n s e r v a t i v e t h a n t h e d e p r e s s e d group, b u t this c o m p a r i s o n d i d n o t r e a c h s t a t i s t i c a l signif i c a n c e . T h e s e r e s u l t s sue" ;t t h a t t h e c o m b i n e d e f f e c t s of d e m e n t i a a n d d e p r e s s i o n h a v e a " c o n s e r v a t i z i n g " e f f e c t on r e s p o n s e b i a s in d e m e n t e d / d e p r e s s e d p a t i ents. Th i s " c o n s e r v a t i z i n g " e f f e c t m a y p r o v i d e u s e f u l i n f o r m a t i o n when c o n s i d e r i n g if a n u n d e r l y i n g d e p r e s s i o n e x i s t s in a d e m e n t e d p a tient. E x a m i n e r s Qt^fried Spjreen, Ph.D., S u p e r v i s o r . — i - r f — — — M i -fc mtv — w — — i — w , P a m Duncan, Ph.D., D e p a r t m e n t a l M e m b e r , _ « ■ ■ ____ M i c h a e l . J o s c h k o , Ph.D, D e p a r t m e n t a l M e m k e r C. B r i a n ^ ^ r j a ^ ^ P h . D . , o u t s i d e M e m b e r H o l l y A. Tuokko, Ph.D., E x t e r n a l E x a m i n e r

TABLE OF CONTENTS A b s t r a c t ... • ii T a b l e of C o n t e n t s . . . iv L i s t of T a b l e s . . ..., ... ... vi L i s t of F i g u r e s . ... vii A c k n o w l e d g e m e n t s . ... .viii D e d i c a t i o n . ... ix 1. I N T R O D U C T I O N ... , . ... * ... 1 II. L I T E R A T U R E R E V I E W ... 5 A. D e f i n i t i o n a n d P r e v a l e n c e of D e m e n t i a . ... ...5 B. D e f i n i t i o n a n d P r e v a l e n c e of D e p r e s s i o n in the E l d e r l y ... 11 C. D i f f e r e n t i a l D i a g n o s i s of Dementit v e r s u s Depre s s i o n . ... 16 1. H i s t o r i c a l and C l i n i c a l V a r i a b l e s . ... 17 2. N e u r o p s y c h o l o g i c a l Var i a b l e s . ... .20 a. P a t t e r n of P e r f o r m a n c e on t h e W e c h s l e r S c a l e s . ... 20 b. L a n g u a g e ... 21 c . M e m o r y ... . . . 2 1 d. D i s c r i m i n a t i o n a n d R e s p o n s e Bi a s I n d i c e s .... 26 3. s u m m a r y ... ... ... ... . 3 6 D. C o e x i s t e n t D e m e n t i a and D e p r e s s i o n : P r i o r A t t e m p t s at D i a g n o s i s ... 37 1. M e t a b o l i c S t u d i e s ...42 2. S l e e p E n c e p h a l o g r a p h i c S t u d i e s ...43 3 . N e u r o p s y c h o l o g i c a l Studies. ... 44 E. P u r p o s e of t h e P r e s e n t S t u d y . ... 46 I I I . H Y P O T H E S E S ... 47 IV. M E T H O D S ... ...50 A. S u b j e c t s ... 50 B. P r o c e d u r e . ... 52 C. D a t a A n a l y s i s ... ...56

V V , RE S U L T S ( t y * i r « : n ■ « » < « i t • < « • » * M > f f * :* f • • < t M « It f 4 I t I i t b 0 A. D e m o g r a p h i c s a n d C l i n i c a l V a r i a b l e s - ...98 B : D i s c r i m i n a t i o n A b i l i t i e s / H y p o t h e s i s i . . . . ...63 C. R e s p o n s e B i a s / H y p o t h e s i s 2 " ... . ... , ... 67 D. A s s o c i a t i o n s B e t w e e n I n d i c e s of D i s c r i m i n a t i o n a n d R e s p o n s e B i a s a n d M e a s u r e s of D e m e n t i a and D e p r e s s i o n / H y p o t h e s i s 3 ... , ... 72 V I . D I S C U S S I O N . . , ,... 84 A. S u m m a r y of H y p o t h e s e s . . . ... 84 1. D i s c r i m i n a t i o n A b i l i t i e s / H y p o t h e s i s l ...84 2. R e s p o n s e B i a s / H y p o t h e s i s 2 ... ... 87 3. A s s o c i a t i o n s B e t w e e n I n d i c e s of D i s c r i m i n i t i o n a n d R e s p o n s e B i a s and M e a s u r e s of D e m e n t i a and D e p r e s s i o n / H y p o t h e s i s 3 ... ... 92 B. G e n e r a l D iscussion. ... ,98 R e f e r e n c e s . ... 104 A p p e n d i x A: E x a m p l e s of G e o m e t r i c and N o n s e n s e F i g u r e s f r o m K i m u r a ' s R e c u r r i n g F i g u r e s T e s t . . . . .... llfj A p p e n d i x B : R a w D a t a ... ..116

T a b l e x: D e m o g r a p h i c D a t a for Each D i a g n o s t i c G r o u p . ... ..59 T a b l e 2: D e p r e s s i o n R a t i n g s for E a c h D i a g n o s t i c G r o u p . . . . 60 T a b l e 3; Sc o r e s on M e a s u r e s o f C o g n i t i v e A b i l i t y in E a c h D i a g n o s t i c G r o u p ...■... 62 T a b l e 4: C o r r e l a t i o n s B e t w e e n M e a s u r e s of C o g n i t i v e A b i l i t y and D i s c r i m i n a b i l i t y ... 73 T a b l e 5: C o r r e l a t i o n s B e t w e e n R a t i n g s of D e p r e s s i o n S e v e r i t y and D i s c r i m i n a b i l i t y . ... ... 75 T a b l e 6: C o r r e l a t i o n s B e t w e e n R a t i n g s of D e p r e s s i o n S e v e r i t y and D i s c r i m i n a b i l i t y in Each D i a g n o s t i c G r o u p ... 77 T a b l e 7: C o r r e l a t i o n s B e t w e e n M e a s u r e s of C o g n i t i v e A b i l i t y and R e s p o n s e Bias... 78 T a b l e 8: C o r r e l a t i o n s B e t w e e n R a t i n g s of D e p r e s s i o n S e v e r i t y and R e s p o n s e B i a s ... 80 T a b l e 9: R e g r e s s i o n C o e f f i c i e n t s for D i s c r i m i n a t i o n I n d i c e s ... 81 T a b l e 10: R e g r e s s i o n C o e f f i c i e n t s for R e s p o n s e B i a s I n d i c e s ... .83

vii

ACKNOWLEDGEMENTS

I e x t e n d m y t h a n k s to a l l t h e p a r t i c i p a n t s in t h i s study; it was t h e i r c o o p e r a t i o n and p e r s e v e r a n c e th a t m a d e t h i s p r o j e c t possible.

X t h a n k m y c o m m i t t e e m embers, Drs. P a m Duncan, M i c h a e l Joschko, and B r i a n Harvey, a n d m y e x t e r n a l examiner, Dr. H o l l y Tuokko, for t h e time, c o n s i d e r a t i o n , and k i n d n e s s e x t e n d e d t o m e t h r o u g h o u t t h i s process. I am m o s t g r a t e f u l to t h e m for c r e a t i n g a l i g h t - h e a r t e d , s u p p o r t i v e a t m o s p h e r e d u r i n g m y oral defense. A s p e c i a l note o f t h a n k s goes to m y f' p a r v i s o r , Dr. O t f r i e d spreen, w h o has p a t i e n t l y and g e n t l y

e n c o u r a g e d m e t h r o u g h o u t m y y e a r s at t h e U n i v e r s i t y of V ictoria. X a l s o t h a n k t h e U n i v e r s i t y of V i c t o r i a for its g e n e r o u s f e l l o w s h i p support.

I a m g r a t e f u l to m a n y m e m b e r s of t h e s t a f f at L o n g I s l a n d J e w i s h - H i l l s i d e M e d i c a l Center, e s p e c i a l l y Dr. B i l l B a r r and Dr. R o b e r t Bilder, for t h e i r i n v a l u a b l e g u i d a n c e a n d a s s i s t a n c e in d e v e l o p i n g , implem e n t i n g , a n d c o m p l e t i n g t h i s study.

I t h a n k m y f r i e n d s for t h e i r m a n y r e a s s u r a n c e s , and e s p e c i a l l y J e n n i B l a i r T h o m s o n for her a l w a y s l i s t e n i n g ear a n d c a l m i n g spirit.

Finally, s p e c i a l t h a n k s go to m y family, e s p e c i a l l y my Mom, Dad, a n d s i s t e r M a r g a r e t , a n d to John, f o r t h e i r

U n c o n d i t i o n a l a n d c o n s t a n t support, e n c o u r a g e m e n t , patie n c e , a n d prayers.

DEDICATION

To m y family

"It is the v e r y b e s t of g i f t s G o d gave,

You t a k e it w i t h y o u f r o m t h e c r a d l e to the grave; It is a f a m i l y tie, It i s a f a m i l y t i e th a t binds," M a u r a O ' C o n n e l l "A F a m i l y Tie"

M a j o r d e p r e s s i o n c o m p l i c a t e s u n e q u i v o c a l d e m e n t i a in 1 0 - 2 0 % of d e m e n t e d p a t i e n t s and s i g n i f i c a n t d e p r e s s i v e

f e a t u r e s o c c u r in 40-50% of d e m e n t e d p a t i e n t s (Wragg, 1989). T h e d i a g n o s i s of d e p r e s s i o n in d e m e n t e d patie n t s , however, is o f t e n c o n f o u n d e d b y the o v e r l a p of s y m p t o m s of d e p r e s s i o n and d e m e n t i a (e.g., p s y c h o m o t o r changes, a p p e t i t e a n d s l eep d i s t u r b a n c e s , d i m i n i s h e d i n t e r e s t ) . T h e s e symptoms, c o m m o n l y a s s o c i a t e d w i t h d epression, are a l s o o f t e n p a r t of the

d e m e n t i a s y n d r o m e in p a t i e n t s w h o do n o t h a v e d e p r e s s i o n (Greenwald, Mathe, Mohs, Levy, Johns, and Davis, 1986). T h e refore, a c o m m o n c l i n i c a l c i r c u m s t a n c e is t h e d e m e n t e d p a t i e n t w h o is s u s p e c t e d of h a v i n g d e pression, b u t w h e r e i n t h e c l i n i c i a n c a n n o t c o n f i d e n t l y d i s c r i m i n a t e t h e d i a g n o s i s of d epression. conver s e l y , d e p r e s s i o n in t h e e l d e r l y is o f t e n a c c o m p a n i e d b y d e p r e s s i o n - d e p e n d e n t c o g n i t i v e i m p a i r m e n t t h a t is r e v e r s i b l e f o l l o w i n g a n t i d e p r e s s a n t t herapy. This c o n d i t i o n has b e e n r e f e r r e d to as " p s e u d o d e m e n t i a " (Kiloh, 1961), " d e m e n t i a s y n d r o m e of d e p r e s s i o n " ( F o l s t e i n and McHugh, 1978), and m o r e r e c e n t l y " d e p r e s s i o n w i t h c o g n i t i v e i m p a i r m e n t " (Folstein and Rabins, 1991). D i a g n o s i s of

d e p r e s s i o n in d e m e n t e d i n d i v i d u a l s is c r i t i c a l s i n c e the d e v e l o p m e n t of d e p r e s s i o n s u p e r i m p o s e d u p o n a d e m e n t i a m a y be a c c o m p a n i e d b y a r e v e r s i b l e d e p r e s s i o n - d e p e n d e n t

f u n c t i o n i n g of the p a t i e n t (Breen/ Larson, Peiflor,

v I t a l i a n © , and L a w r e n c e , 1984; Gre e n w a l d , Kram e r , Ginsb e r g , Marin, Hermann, Mohs, and Davis, 1989? M c A l l i s t e r a n d Prion, 1982; Rcvner, Broadhead, Spancer, Carson, and Fo I stein,

1989; Shraberg, 1978; S n o w a n d Wells, 1981). S o m a t i ;

a n t i d e p r e s s a n t t r e a t m e n t s h a v e b e e n s h o w n t o i m p r o v e mo o d (Reifler, Larson, Teri, and Poulson, 1986; Reifler, Tori, R a skind, Voith, Barnes, White, and McLean, 1989? Reynolds, Perel, Kupfer, Zimmer, Stack, a n d Hoch, 1987; Sn o w and

Wells, 1981) a n d c o g n i t i v e s t a t u s (Greenwald, et a!., 1989; M c A l l i s t e r a n d Price, 1982; Snraberg, 1978) in d e m e n t e d p a t i e n t s w i t h a s u p e r i m p o s e d d e p r e s s i o n . C o g n i t i v e f u n c t i o n i n g i m p r o v e s p r e s u m a b l y on t h e b a s i s of r e m i s s i o n of d e p r e s s i o n a n d a l l e v i a t i o n of d e p r e s s i o n - m e d i a t e d c o g n i t i v e d e f i c i t s . T h e r e f o r e , s u c c e s s f u l i d e n t i f i c a t i o n and t r e a t m e n t of d e p r e s s i o n in d e m e n t e d p a t i e n t s m a y r e p r e s e n t t h e o n l y " i m p r o v a b l e " c o m p o n e n t in an o t h e r w i s e u n r e m i t t i n g c o g n i t i v e d e t e r i o r a t i o n . T h e e s t a b l i s h m e n t of a n e u r o p s y c h o l o g i c a l t o o l to a i d t h e i d e n t i f i c a t i o n of d e p r e s s i o n in d i a g n o s t i c a l l y e n i g m a t i c d e m e n t e d p a t i e n t s w o u l d b e an i m p o r t a n t c o n t r i b u t i o n to d i f f e r e n t i a l d i a g nosis. A t pr e s e n t , however, l i t t l e is k n o w n a b o u t t h e p e r f o r m a n c e o f d e m e n t e d p a t i e n t s w i t h d e p r e s s i o n on n e u r o p s y c h o l o g i c a l measures. T h e c u r r e n t s t u d y was d e s i g n e d to f u r t h e r i n v e s t i g a t e t h e c o g n i t i v e f u n c t i o n i n g of d e m e n t e d p a t i e n t s w i t h

d e p r e s s i o n and. t o a t t e m p t to i d e n t i f y d i s t i n g u i s h i n g c h a r a c t e r i s t i c s t h a t m a y a s s i s t w i t h d i f f e r e n t i a l diagnosis. S p e c i f i c a l l y , d e m e n t e d / d e p r e s s e d p a t i e n t s w e r e c o m p a r e d to n o n - d e p r e s s e d d e m e n t e d ~nd n o n - d e m e n t e d d e p r e s s e d p a t i e n t g r o u p s on a f o r c e d - c h o i c e r e c o g n i t i o n m e m o r y task, w h i c h y i e l d s i n d i c e s of d i s c r i m i n a t i o n a b i l i t y a n d r e s p o n s e bias. R e s p o n s e bi a s r e f l e c t s the r e s p o n d e n t ' s t e n d e n c y to s a y "yes" or "ho" w h e n u n c e r t a i n if a g i v e n s t i m u l u s is a t a r g e t or a d i s t r a c t o r item. R e s u x t s of p r i o r r e s e a r c h i n d i c a t e d t h a t d i s c r i m i n a t i o n a b i l i t i e s w e r e b e t t e r in d e p r e s s e d p a t i e n t s t h a n in d e m e n t e d p a t i e n t s a n d t h a t d e p r e s s e d p a t i e n t s m a n i f e s t e d a c o n s e r v a t i v e r e s p o n s e bi a s (i.e., t h e y t e n d e d to say "no" m o r e o f t e n w h e n unc e r t a i n ) w h i l e d e m e n t e d p a t i e n t s s h o w e d a m o r e l i b eral r e s p o n s e b i a s (i.e., t h e y t e n d e d to say “ yes" m o r e often) (Brandt, Corwin, and Krafft, 1992; Corwin, Pe s e l o w , Feenan, R o t r o s e n , a n d Fieve, 1990; Hart, Smith, a n d Swash, 1985; Larner, 1977; Massman, Delis, Butters, Levin, a n d Salmon, 1990; M i l l e r a n d Lewis, 1977; Nie d e r e h e , 1986; S n o d g r a s s a n d Corwin, 1988). T h i s s t u d y w i l l a t t e m p t to r e p l i c a t e t h e s e f i n d i n g s a n d n e w l y a d d r e s s th e n a t u r e of d i s c r i m i n a t i o n a b i l i t y a n d r e s p o n s e b i a s in d e m e n t e d p a t i e n t s w i t h d epression. B y i d e n t i f y i n g d i s c r e t e c o g n i t i v e c h a r a c t e r i s t i c s of t h i s d i a g n o s t i c a l l y e n i g m a t i c group, d e m e n t e d p a t i e n t s w i t h d e p r e s s i o n m a y b e m o r e r e a d i l y id e n t i f i e d .

4

II, LITERATURE REVIEW

A- D E F I N I T I O N A N D P R E V A L E N C E O F D E M E N T I A

D e m e n t i a m a y be b r o a d l y d e f i n e d as an u n u s u a l loss of i n t e l l e c t u a l f u n c t i o n that is b e y o n d w h a t w o u l d be e x p e c t e d d u e t o n o r m a l a g i n g (Joynt a n d Shoulson, 1985). Cummings, Benson, and L o V e r m e (1980) d e f i n e d d e m e n t i a m o r e

s p e c i f i c a l l y as an a c q u i r e d p e r s i s t e n t loss of i n t e l l e c t u a l f u n c t i o n W i t h c o m p r o m i s e d a b i l i t i e s in at l e a s t t h r e e of t h e f o l l o w i n g five areas: c o g n i t i o n ( i , e . , a b s t r a c t i o n ,

c a l c u l a t i o n , j u d g e m e n t ) , memory, v i s u o s p a t i a l skills, language, and personality.

In an a t t e m p t to ga i n s o m e u n i f o r m i t y in t h e d i a g n o s i s of dementia, t h e N a t i o n a l I n s t i t u t e of N e u r o l o g y and

C o m m u n i c a t i o n D i s o r d e r s and S t r o k e (NINCDS) a n d the A l z h e i m e r ' s D i s e a s e a n d R e l a t e d D i s o r d e r s A s s o c i a t i o n

(ADRDA) (McKhann, Drachman, Folstein, Katzman, Price, and Stadlan, 1984), o u t l i n e d c r i t e r i a for t h e d i a gnosis, w h i c h i n c l u d e d " . . . t h e d e c l i n e of m e m o r y a n d o t h e r c o g n i t i v e f u n c t i o n s in c o m p a r i s o n w i t h t h e p a t i e n t ' s p r e v i o u s l e v e l of f u n c t i o n i n g as d e t e r m i n e d b y h i s t o r y of d e c l i n e in p e r f o r m a n c e and b y a b n o r m a l i t i e s n o t e d f r o m c l i n i c a l e x a m i n a t i o n and n e u r o p s y c h o l o g i c a l t e s t s . " T h e d i a g n o s i s c a n n o t be m a d e w h e n c o n s c i o u s n e s s is impaired. T h e N I N C D S - A D R D A r e p o r t f u r t h e r p o i n t e d out t h a t d e m e n t i a is a. d i a g n o s i s b a s e d on b e h a v i o r a n d c a n n o t b e d e t e r m i n e d by

h

c o m p u t e d tomogr a p h y , e l e c t r o e n c e p h a l o g r a p h y , or o t her

l a b o r a t o r y i n s t r u m e n t s (although c a u s e s of d e m e n t i a m a y bo d i s c o v e r e d w i t h t h e aid of t h e s e t e c h n i q u e s ) .

T he d e f i n i t i o n of d e m e n t i a was o p e r a t i o n a l i s e d t o a s o m e w h a t g r e a t e r e x t e n t in the D i a g n o s t i c and Statist it ii M a n u a l of M e n t a l D i s o r d e r s (Third E d i t i o n ~ R e v i s ed) (DSM I X I - R ; A m e r i c a n P s y c h i a t r i c A s s o c i a t i o n , 1987). T h e D D M 1i i - B d e f i n e s d e m e n t i a as an o v e r a l l d e c l i n e in i n t e l l e c t u a l f u n c t i o n i n g ; t h e e s s e n t i a l f e a t u r e is i m p a i r m e n t in s h o r t a n d long te r m m e m ory, and is a s s o c i a t e d w i t h .it least one of t h e following: 1) i m p a i r m e n t in a b s t r a c t t h i n k i n g (e.g., d i f f i c u l t y w i t h n o v e l tasks), 2) i m p a i r e d j u d g e m e n t (e.g., i n a p p r o p r i a t e joking, n e g l e c t of p e r s o n a l a p p e a r a n c e ) , 3) o t h e r d i s t u r b a n c e s of h i g h e r c o r t i c a l f u n c t i o n (e.g.,

aphasia, apraxia, agnosia), or 4) p e r s o n a l i t y c h a n g e (i.e., e i t h e r a n a l t e r n a t i o n or an a c c e n t u a t i o n of p r e m o r b i d t r a i t s ) . T h e s e d i s t u r b a n c e s m u s t be s i g n i f i c a n t e n o u g h to i n t e r f e r e w i t h work, u s u a l s o c i a l a ctivities, or r e l a t i o n s h i p s w i t h o t h e r s and m u s t o c c u r wh e n c o n s c i o u s n e s s is intact. In addition, D S M I I I - R r e q u i r e s e v i d e n c e of an o r g a n i c e t i o l o g i c f a c t o r r e l a t e d t o t h e d i s t u r b a n c e (from h istory, p h y s i c a l e x a m i n a t i o n , or l a b o r a t o r y t e s t s ) ; if an o r g a n i c b a s i s t o t h e d i s t u r b a n c e c a n n o t b e d e t e r m i n e d , it m a y be p r e s u m e d if t h e p r e s e n t i n g s y m p t o m s c a n n o t be a c c o u n t e d for by a " n o n o r g a n i c m e n t a l d i s o r d e r " , s u c h as M a j o r D e p r e s s i o n . D S M I I I - R d i v i d e s d e m e n t i a in t o g e n e r a l

i n c l u d i n g P r i m a r y D e g e n e r a t i v e D e m e n t i a of th e A l z h e i m e r Type, r u l t i - I n f a r c t Dementia, a n d D e m e n t i a N o t O t h e r w i s e Specified. C u r r e n t e s t i m a t e s s u g g e s t t h a t a p p r o x i m a t e l y six p e r c e n t of p e r s o n s o v e r age 65 h a v e s e v e r e d e m e n t i a and an a d d i t i o n a l 10-15% h a v e m i l d to m o d e r a t e d e m e n t i a (Cummings and Benson, 1992). T h e p r e v a l e n c e of d e m e n t i a d o u b l e s a p p r o x i m a t e l y e v e r y fi v e y e a r s a f t e r a g e 65 (Jorm, Korten, and Henderson, 1987). It is e x p e c t e d t h a t t h i s p o p u l a t i o n g r o u p wi l l t r i p l e b y t h e y e a r 2050 d u e to a b u l k of t h e so- c a l l e d " b a b y - b o o m e r " g e n e r a t i o n e n t e r i n g t h e i r s e n i o r years; in addition, i m p r o v e d h e a l t h c a r e is h e l p i n g m a n y

i n d i v i d u a l s in t h i s age g r o u p live l o n g e r lives.

D e m e n t i a is a s y m p t o m of m a n y d i f f e r e n t d i s o r d e r s a n d not a d i s e a s e u n t o itself. C a u s e s of d e m e n t i a i n c l u d e

s truct u r a l , m e t a b o l i c , toxic, a n d p s y c h i a t r i c a b n o r m a l i t i e s . T h e m o s t c o m m o n c a u s e of d e m e n t i a is A l z h e i m e r ' s

d i s e a s e (AD), w h i c h has b e e n f o u n d to a c c o u n t for 50 - 70 % of o l d e r p a t i e n t s w i t h d e m e n t i a seen in p s y c h i a t r i c p r a c t i c e (Kaszniak, 1986). C u m m i n g s a n d B e n s o n (1992) cau t i o n e d , however, t h a t t h e s e f i g u r e s m a y be o v e r e s t i m a t e s ; t h a t is, s i n c e the d i a g n o s i s of A D is o n e of e x c l u s i o n b a s e d on t h e a b s e n c e of o t h e r i d e n t i f i a b l e c a u s e s of d e m e ntia, s u c h a c a t e g o r y is l i k e l y to i n c lude u n r e c o g n i z e d c a u s e s of d e m e n t i a in a d d i t i o n to t r u e c a s e s of AD.

8

l a n g u a g e a b n o r m a l i t i e s , v i s u o s p a t i a l i m p a i r m e n t , i m p a i r e d a b s t r a c t i o n and c a l c u l a t i o n , p e r s o n a l a n d b e h a v i o r a l

changes, a n d i n t a c t m o t o r f u n c t i o n (Cummings, 198?). A D has a n i n s i d i o u s o n s e t and p r o g r e s s e s gradually, o f t e n leading t o d e a t h in 6-12 years.

As m e n t i o n e d , t h e d i a g n o s i s o f AD is one of exclusion; t h a t is, o t h e r s y s t e m i c or b r a i n d i s e a s e s w h i c h may a c c o u n t fo r t h e c o g n i t i v e d e t e r i o r a t i o n m u s t f i r s t b e r u l e d out. T h e N I N C D S - A D R D A o u t l i n e d c r i t e r i a for possi b l e , probable, a n d d e f i n i t e A D ( McKhann et a l . , 1984). A d i a g n o s i s of d e f i n i t e A D r e q u i r e s h i s t o p a t h o l o g i c a l evidence, o b t a i n e d f r o m b i o p s y or a u topsy, of an e x c e s s n u m b e r of n e u r o f i b r i l l a r y t a n g l e s and s e n i l e p l a q u e s in the c e r e b r a l cortex. T h e h i p p o c a m p u s a n d a m y g d a l a a r e u s u a l l y m o s t s e v e r e l y a f f e c t e d , w i t h m a r k e d c o r t i c a l i n v o l v e m e n t of the f r o n t a l a n d t e m p o r a l l o b e s and l e s s i n v o l v e m e n t of the p a r i e t a l a n d o c c i p i t a l a r e a s (Tomlinson, 1977).

Th e s e v e r i t y of d e m e n t i a was shown to c o r r e l a t e with t h e n u m b e r of s e n i l e p l a q u e s in t h e c e r e b r a l c o r t e x

(Blessed, T o m l i n s o n , a n d Roth, 1968). T h e d e n s i t y o f p l a q u e s w a s a l s o s h o w n t o c o r r e l a t e wi t h the r e d u c t i o n of c h o l i n e

a c e t y i t r a n s f e r a s e (ChAT, t h e e n z y m e r e s p o n s i b l e for the s y n t h e s i s o f a c e t y l c h o l i n e ) , w h i c h was al s o s h o w n to c o r r e l a t e w i t h t h e s e v e r i t y of t h e d e m e n t i a (Perry,

r e d u c t i o n in C h A T a c t i v i t y in A D is r e l a t e d to a loss of c h o l i n e r g i c n e u r o n s in the b a s a l f o r e b r a i n and s e p t a l areas, w h i c h h a v e w i d e s p r e a d p r o j e c t i o n s to t h e c e r e b r a l c o r t e x and h i p p o c a m p u s (Mesulam a n d V a n Hoesen, 1976). R e d u c t i o n s in t h e n o r a d r e n e r g i c a n d s e r o t o n e r g i c s y s t e m s h a v e also b e e n r e p o r t e d (Bondureff, Mount j o y , and Roth, 1981; Mann,

Lincoln, Yates, Stamp and Toper, 1980; M a n n and Yates, 1983). M u l t i p l e c e r e b r a l i n f a r c t i o n s a r e t h e s e c o n d m o s t c o m m o n c a u s e of d e m e n t i a ( m u l t i - i n f a r c t d e m e n t i a , MID) , a c c o u n t i n g for a p p r o x i m a t e l y 15 - 25% of t h e c a s e s (Kazniak, 1986). M I D is c h a r a c t e r i z e d by an a b r u p t onset, s t e p w i s e d e t e r i o r a t i o n , a f l u c t u a t i n g course, n o c t u r n a l c o n fusion, r e l a t i v e p r e s e r v a t i o n of p e r s o n a l i t y , d e p r e s s i o n , s o m a t i c c o m p l a i n t s , e m o t i o n a l lability, e v i d e n c e of a s s o c i a t e d a t h e r o s c l e r o s i s , a h i s t o r y of h y p e r t e n s i o n , stroke, or t r a n s i e n t n e u r o l o g i c symptoms, and f o c a l n e u r o l o g i c s i g n s on p h y s i c a l e x a m i n a t i o n (Cummings, 1987). T h e c l i n i c a l f e a t u r e s d e p e n d on t h e l o c a t i o n and s i z e of t h e infarcts. D e m e n t i a h a s a l s o be e n a s s o c i a t e d w i t h d e g e n e r a t i v e d i s e a s e s of t h e s u b c o r t i c a l systems, s u c h as P a r k i n s o n ' s d i s e a s e a n d H u n t i n g t o n ' s disease. T h e c o g n i t i v e i m p a i r m e n t s a s s o c i a t e d w i t h s u b c o r t i c a l d y s f u n c t i o n i n c l u d e d e f i c i t s in arousal, a t t ention, m o t i v a t i o n , a n d a s l o w e d r a t e of i n f o r m a t i o n p r o c e s s i n g . M e m o r y d i s t u r b a n c e s i n c l u d e f o r g e t f u l n e s s , c h a r a c t e r i z e d by d i f f i c u l t y s p o n t a n e o u s l y

10

d e p r e s s i o n a n d m o r e r a r e l y mania) h a v e be e n d e s c r i b e d (Cumm i n g s and Benson, 1992).

D e m e n t i a m a y al s o r e s u l t f r o m p o t e n t i a l l y r e v e r s i b l e causes, s u c h a s m e t a b o l i c d e f i c i e n c i e s (e.g., a B12 d e f i c i e n c y ) , t o x i c c o n d i t i o n s (e.g., m i s u s e of m e d i c a t i o n ) , or t r e a t a b l e d i s e a s e s (e.g., p u l m o n a r y or c a r d i a c i n s u f f i c i e n c y , or e n d o c r i n o p a t h y ) (Benson, 1982)* P o t e n t i a l l y r e v e r s i b l e c a u s e s of dementia, w e r e found to a c c o u n t f o r 13,2% of p a t i e n t s p r e s e n t i n g w i t h c o g n i t i v e i m p a i r m e n t (Clairfieid, 1980). A c o m m o n p o t e n t i a l l y r e v e r s i b l e c a u s e of c o g n i t i v e i m p a i r m e n t in t h e e l d e r l y Is an u n d e r l y i n g p s y c h i a t r i c d i s t u r b a n c e , w h i c h is m o s t o f t e n a s e v e r e f o r m of d e p r e s s i o n . C o g n i t i v e i m p a i r m e n t d u e to d e p r e s s i o n has be e n t e r m e d " p s e u d o d e m e n t i a " (Kiloh, 1961), t h e " d e m e n t i a

s y n d r o m e of d e p r e s s i o n " (Folstein and McHugh, 1978), and m o r e r e c e n t l y " d e p r e s s i o n w i t h c o g n i t i v e i m p a i r m e n t " ( F o l s t e i n a n d Rabins, 1992). In s u c h c ases c o g n i t i v e s y m p t o m s r e m i t f o l l o w i n g a p p r o p r i a t e a n t i d e p r e s s a n t t r e a t m e n t . In a r e c e n t s e r i e s of s t u d i e s d e p r e s s i o n was f o u n d t o a c c o u n t for 4.5% of n e a r l y 3000 p a t i e n t s p r e s e n t i n g w i t h c o g n i t i v e d i f f i c u l t i e s (clairfieid, 1988).

A r e v i e w of t h e l i t e r a t u r e by Btoudmire, Hill, Gulley, a n d M o r r i s (1989) i n d i c a t e d t h a t w h i l e t h e m a j o r i t y of

d e p r e s s e d p a t i e n t s do n o t e x h i b i t c o g n i t i v e difficuicj.es, a p r e d o m i n a n t l y e l d e r l y s u b g r o u p of p a t i e n t s d o e s s h o w sigis of d e p r e s s i o n - r e l a t e d c o g n i t i v e d y s f u n c t i o n . T h e c o g n i t i v e d i f f i c u l t i e s t h a t a c c o m p a n y d e p r e s s i o n a r e m o s t o f t e n

r e l a t e d to attention, memory, and s p e e d of p r o c e s s i n g , w h i l e d i s o r d e r s of c o r t i c a l l y - m e d i a t e d f u n c t i o n s (e.g., aphasia, apraxia, agnosia) are u s u a l l y a b s e n t (Miller, 1975; Caine, 1981, 198 6). T h e p a t t e r n of d e f i c i t s is s i m i l a r to t h a t a s s o c i a t e d w i t h d e m e n t i a of a s u b c o r t i c a l origin, s u c h as H u n t i n g t o n ' s d i s e a s e (Massmah, Delis, Butters, DuPont, a n d Gillin, 1992). D e t e r m i n i n g if p r e s e n t i n g c o g n i t i v e d e f i c i t s are r e l a t e d to an u n d e r l y i n g d e p r e s s i o n or t o a d e m e n t i n g d i s o r d e r is o f t e n difficult. I s s u e s r e l a t e d t o d i f f e r e n t i a l d i a g n o s i s w i l l b e a d d r e s s e d in l a t e r sections. B. D E F I N I T I O N A N D P R E V A L E N C E O F D E P R E S S I O N IN T H E E L D E R L Y T h e e s s e n t i a l f e a t u r e o f a M a j o r D e p r e s s i v e episode, as d e f i n e d by DSM I I I - R . is e i t h e r a d e p r e s s e d m o o d o r a loss of i n t e r e s t or p l e a s u r e in m o s t a c t i v i t i e s . In t h e e l d e r l y t h i s m a y m a n i f e s t as a s e nse of h o p e l e s s n e s s or i n t e n s e i r r i t a b i l i t y . T h e s e s y m p t o m s r e p r e s e n t a c h a n g e f r o m

p r e v i o u s functioning, o c c u r m o s t o f the d a y n e a r l y e v e r y day f or a p e r i o d Of at l e a s t two weeks, and are a s s o c i a t e d w i t h a p p e t i t e a n d / o r sleep d i s t u r b a n c e s , w e i g h t changes,

12

c a t e c h o l a m i n e r g i c f u n c t ioning, p a r t i c u l a r l y n o r e p i n e p h e r i n e , h a v e b e e n i m p l i c a t e d as t h e b i o c h e m i c a l b a s i s to d e p r e s s i o n

(Schiidkraut, 1965).

D e p r e s s i v e d i s o r d e r s are the m o s t c o m m o n

p s y c h o p a t h o l o g i c d i s t u r b a n c e s f o u n d in t h e e l d e r l y (Butler, Lewis, a n d S u nderland, 1991). Da t a r e p o r t e d by the N a t i o n a l I n s t i t u t e of H e a l t h (NIH; 1991) i n d i c a t e d t h a t d e p r e s s i v e s y m p t o m s o c cur in a p p r o x i m a t e l y 15% of c o m m u n i t y r e s i d e n t s o v e r the a g e of 65 a n d a m a j o r d e p r e s s i v e s y n d r o m e o c c u r s In a p p r o x i m a t e l y 3%. In addition, t h e r a t e of c o m p l e t e d

s u i c i d e s f o r o l d e r p e o p l e is h i g h e r t h a n t h a t of the g e n e r a l p o p u l a t i o n . For example, in 1988 t h e s u i c i d e r a t e in the g e n e r a l p o p u l a t i o n of t h e U n i t e d s t a t e s w a s 1 2 . 4/100,000, w h i l e t h e r a t e in t h e 30-84 y e a r old a g e g r o u p was

2 6 . 5 / 1 0 0 , 0 0 0 . E l d e r l y w h i t e m e n w e r e at g r e a t e s t r i s k for s u c c e s s f u l l y c o m p l e t i n g a suicide.

D i a g n o s i s of d e p r e s s i o n in t h e e l d e r l y c a n be a

d i f f i c u l t task. S l e e p and a p p e t i t e c h a n g e s o c c u r in nor m a l a g i n g (Butler e t al., 1991; Dement, Miles, and carskadon, 1982) a n d f a t i g u e m a y be r e l a t e d to h e a l t h p r o b l e m s as o ften as t o d e p r e s s i o n (Salzman a n d Shader, 1979). K a z n i a k and A l l e n d e r (1985) p o i n t e d O u t t h a t p a t i e n t s w i t h o c c u l t

i n c l u d i n g fatigue, p o o r a p p e t i t e a n d w e i g h t lost*, a n d s l eep d i s t u r b a n c e s ; p a t i e n t s w i t h c a r d i a c d i s e a s e a l s o f r e q u e n t l y c o m p l a i n of d i s t u r b e d sleep, fatigue, and d i f f i c u l t i e s with c o n c e n t r a t i o n . Thus, s o m a t i c s y m p t o m s in t h e e l d e r l y m u s t be i n t e r p r e t e d m o r e c a u t i o u s l y t h a n w h e n t h e y p r e s e n t in y o u n g e r p ersons. S o m a t i c s y m p t o m s in the e l d e r l y s h o u l d be a t t r i b u t e d to d e p r e s s i o n o n l y a f t e r a t h o r o u g h p h y s i c a l e v a l u a t i o n (Gallagher, 1986). D i a g n o s i s and t r e a t m e n t of l a t e - l i f e d e p r e s s i o n is c o m p l i c a t e d f u r t h e r b y t h e f r e q u e n t l y o c c u r r i n g admixture, overlap, and i n t e r a c t i o n o f c o g n i t i v e d e f i c i t s and

d e p r e s s i v e s y m p t o m a t o l o g y . S o m e a u t h o r s h a v e n o t e d th a t d e p r e s s e d patients' c o m p l a i n t s a b o u t i m p a i r e d c o g n i t i v e f u n c t ioning, p a r t i c u l a r l y memory, t e n d to o v e r e s t i m a t e t h e e x t e n t of t h e i r a c t u a l diffi c u l t y , as m e a s u r e d by

p s y c h o m e t r i c t e s t s (Kahn, Zarit, H i lbert, N i e d e r e h e , 1975). It has b e e n sug g e s t e d , however, t h a t w h i l e s u c h d i s p a r i t y m a y e x i s t in m i l d l y o r m o d e r a t e l y d e p r e s s e d p a t i e n t s , s e v e r e l y d e p r e s s e d p a t i e n t s a r e m o r e l i k e l y to e x p e r i e n c e s i g n i f i c a n t c o g n i t i v e d i f f i c u l t i e s (Raskin, 1986). Henry, W e i n g a r t n e r , a n d M u r p h y (1973) f o u n d t h a t t h e i n t e n s i t y of d e p r e s s i o n w a s i n v e r s e l y c o r r e l a t e d w i t h h o w m u c h c o u l d be l e a r n e d and r e m e m b e r e d . A s m e n t i o n e d p r e v i o u s l y , a p r e d o m i n a n t l y e l d e r l y s u b g r o u p of d e p r e s s e d p a t i e n t s are e s p e c i a l l y v u l n e r a b l e to d e p r e s s i o n - r e l a t e d c o g n i t i v e d y s f u n c t i o n , c h a r a c t e r i z e d m o s t o f t e n b y d e f i c i t s in

14

B o t h q u a l i t a t i v e and q u a n t i t a t i v e c h a n g e s in c o g n i t i o n o c c u r in depre s s i o n , l e a d i n g to c h a n g e s in t h e e f f i c i e n c y and. e f f e c t i v e n e s s of i n f o r m a t i o n p r ocessing. W e i n g a r t n e r and S i l b e r m a n (1984) r e v i e w e d t h e o r i e s t h a t i n f e r t h a t m o o d

s t a t e s e r v e s to bi a s c o g n i t i v e p r o c e s s i n g . F o r example, Be c k (1972) a r g u e d t h a t d y s f u n c t i o n a l c o g n i t i o n s d e f i n e the

d e p r e s s e d state. T h a t is, in d e p r e s s i o n a n e g a t i v e v i e w of t h e self, world, and future, l o w e r e d s e l f - e s t e e m , and

d e c r e a s e d m o t i v a t i o n s e r v e as a c o g n i t i v e f i l t e r t h r o u g h w h i c h all o t h e r e x p e r i e n c e s are p e r c e i v e d . B e c k ' s t h e o r y of d e p r e s s i o n was r e f o r m u l a t e d in t h e " l e a r n e d h e l p l e s s n e s s " m o d e l (Maier a n d Seligman, 1976) . Th i s m o d e l c o n t e n d s th a t d e p r e s s e d p a t i e n t s e x p e c t u n f a v o r a b l e e v e n t s t o occur, feel t h e y h a v e n o c o n t r o l o v e r t h e s e n e g a t i v e c o n s e q u e n c e s , and as a r e s u l t d e m o n s t r a t e p a s s i v i t y and a n e g a t i v e c o g n i t i v e set. It h a s b e e n a r g u e d t h a t s u c h a n e g a t i v e c o g n i t i v e sot a f f e c t s n o t o n l y o n e ' s p e r c e p t i o n of o n g o i n g events, b u t a l s o a c c e s s i b i l t y a n d r e t r i e v a l of i n f o r m a t i o n a l r e a d y in m e m o r y (Weingartner, Miller, and Murphy, 1977). For example,

it w a s f o u n d t h a t in d e p r e s s i o n n e g a t i v e p a s t e x p e r i e n c e s w e r e m o r e l i k e l y to be r e m e m b e r e d th a n p o s i t i v e e x p e r i e n c e s

(Breslow, Kocis, & Belkin, 1981; Lishman, 1972) and n e g a t i v e a d j e c t i v e s t h a t h a d b e e n s e l e c t e d p r e v i o u s l y as s e l f -

a d j e c t i v e s ( Z u r o f f , Colu-sy, and W i elgus, 1983). G i v e n t h a t t h e i n t e n s i t y of d e p r e s s i o n w a s s h o w n to c o r r e l a t e w i t h c o g n i t i v e d e f i c i t s (Henry et a l . , 1973), it s e e m s p l a u s i b l e t h a t the q u a l i t a t i v e c h a n g e s in c o g nition, w h i c h h a v e b e e n u s e d to d e f i n e m o o d s t a t e b y t h e a u t h o r s c i t e d above/ m a y b e r e l a t e d t o t h e q u a n t i t a t i v e c o g n i t i v e lo s s e s e x p e r i e n c e d ih d epression. W e i n g a r t n e r and c o l l e a g u e s

(Cohen, W e i n g a r t n e r , Smallberg, Pickar, & Murphy, 1982,* W e i n g a r t n e r , Cohen, Murphy, Martello, & Gerdt, 3 981;

W e i n g a r t n e r et al., 1977) s u g g e s t e d t h a t s u c h q u a l i t a t i v e c h a n g e s c o n t r i b u t e to c h a n g e s in attention, arousal, and m o t i v a t i o n . T h e y p r o p o s e d a ’’c e n t r a l m o t i v a t i o n a l d e f i c i t "

in d e p r e s s i o n b a s e d on the o b s e r v a t i o n t h a t d e p r e s s e d p a t i e n t s s h o w e d m e m o r y d e f i c i t s o n l y w h e n e f f o r t f u l

p r o c e s s i n g (i.e., r e q u i r i n g a c t i v e and s u s t a i n e d c o g n i t i v e activity), as o p p o s e d to a u t o m a t i c p r o c e s s i n g (i.e.,

s o m e w h a t m o r e p a s s i v e and r e q u i r i n g less c o g n i t i v e activity) was required. T h e y p r o p o s e d t h a t c h a n g e s in m o t i v a t i o n a l s t a t e in d e p r e s s i o n m a n i f e s t as q u a n t i t a t i v e d e f i c i t s in l e a r n i n g a n d memory. T h i s t h e o r y w i l l be d e s c r i b e d in m o r e d e t a i l w h e n d i s c u s s i n g q u a l i t a t i v e d i f f e r e n c e s b e t w e e n t h e p e r f o r m a n c e s of d e p r e s s e d a n d d e m e n t e d p a t i e n t s on m e m o r y m e a s u r e s . The o v e r l a p in c o g n i t i v e and d e p r e s s i v e s y m p t o m s in e l d e r l y a f f e c t i v e d i s t u r b a n c e s o f t e n m a k e s it d i f f i c u l t to d e t e r m i n e t h e p r i m a r y e t i o l o g y o f p r e s e n t i n g compla i n t s .

it?

C . D I F F E R E N T I A L D I A G N O S I S O F D E M E N T I A V E R S U S D E P R E S S ION M i s d i a g n o s i s of d e m e n t i a in t h e e l d e r l y is not

u n c o m m o n . E s t i m a t e s of f a l s e - p o s i t i v e i d e n t i f i c a :ion r a n g e f r o m 31% to 57% (Nott and F l e m i n g e r , 1975; Ron, Toone, G a r r alda, and Lishman, 1979). R e t r o s p e c t i v e a n a l y s e s i n d i c a t e d t h a t t h e m a j o r i t y of m i s i d e n t i f i e d c a ses

r e p r e s e n t e d p s y c h i a t r i c d i s orders, the m o s t c o m m o n of w h i c h w a s d e p r e s s i o n (Haward, 1977; M a r s d e n a n d Harrison, 1972; N o t t and Fle m i n g e r , 1975; R o n et al., 1979).

E l d e r l y p a t i e n t s are o f t e n r e f e r r e d for a n e u r o p s y c h o l o g i c a l e x a m i n a t i o n to e v a l u a t e t h e i r c o g n i t i v e a b i l i t i e s a n d to a s s i s t in m a k i n g a d i f f e r e n t i a l d i a g n o s i s of d e p r e s s i o n vs. d e m e n t i a w h e n t h e e t i o l o g y of p r e s e n t i n g s y m p t o m s is u nclear. M u c h e m p h a s i s has be e n p l a c e d on d i s c o v e r i n g c h a r a c t e r i s t i c s of c o g n i t i v e p e r f o r m a n c e t h a t d i s c r i m i n a t e c p r e s s i o n f r o m d e m e n t i a d u e to t h e

r e v e r s i b i l i t y o f c o g n i t i v e i m p a i r m e n t a s s o c i a t e d w i t h d e p r e s s i o n in c o m p a r i s o n to the bleak, p r o g r e s s i v e c o u r s e a s s o c i a t e d w i t h a d e m e n t i n g process. M a n y a s p e c t s of t h e n e u r o p s y c h o l o g i c a l e v a l u a t i o n are u s e d in m a k i n g this d i s t i n c t i o n . *r 1. H i s t o r i c a l a n d C l i n i c a l V a r i a b l e s H i s t o r i c a l and c l i n i c a l v a r i a b l e s h a v e b e e n u s e f u l in h e l p i n g t o d i s c r i m i n a t e p a t i e n t s w h o a r e p r i m a r i l y d e p r e s s e d f r o m t h o s e who a r e s u f f e r i n g fr o m a p r o g r e s s i v e d e m e n t i n g process. In a c l i n i c a l case review, W e l l s (1979) s u m m a r i z e d h i s own o b s e r v a t i o n s , and t h o s e of others, in a n a t t e m p t to o u t l i n e c h a r a c t e r i s t i c s t h a t d i s t i n g u i s h e d t h e t w o

d i s o r d e r s . He r e p o r t e d t h a t in d e p r e s s i o n the o n s e t of c o g n i t i v e s y m p t o m s t e n d e d to be s o m e w h a t abrupt, c o u l d be dated, w i t h so m e precision, p r o g r e s s e d rapidly, and u s u a l l y f o l l o w e d t h e o n s e t O f d e p r e s s i v e symptoms. D e p r e s s e d

p a t i e n t s t e n d e d to c o m p l a i n of c o g n i t i v e loss a n d d e s c r i b e d it in s o m e detail, w h i l e t h e i r b e h a v i o r was o f t e n

i n c c n g r u e n t w i t h t h e e x t e n t of r e p o r t e d c o g n i t i v e losses. In d emen t i a , the o n s e t o f c o g n i t i v e s y m p t o m s was u s u a l l y slow a n d i n s i d i o u s w i t h a g r a d u a l w o r sening. A h i s t o r y of p r i o r p s y c h i a t r i c d y s f u n c t i o n w a s unusual, p a t i e n t s c o m p l a i n e d l i t t l e of c o g n i t i v e loss, a n d w e r e o f t e n u n a w a r e of t h e e x t e n t of t h e i r c o g n i t i v e d i f f i c u l t i e s . D u r i n g formal e v a l u a t i o n , d e p r e s s e d p a t i e n t s a p p e a r e d to p u t f o rth l i t t l e e f f o r t a n d r e s p o n d e d " d o n ’t k n ow" to q u e s t i o n s w i t h so m e

18

Rabins, Merch a n t , and N e s t a d t (1984) c o n d u c t e d a t w o y e a r f o l l o w - u p s t u d y of p a t i e n t s i n i t i a l * y d i a g n o s e d as

e i t h e r i r r e v e r s i b l y d e m e n t e d or s u f f e r i n g c o g n i t i v e loss due t o a m a j o r d e p r e s s i v e episode. T h e y f o u n d t h a t a p a s t

h i s t o r y o f a f f e c t i v e disor d e r , s u b a c u t e unset, a

p e r s i s t e n t l y d e p r e s s e d or d y s p h o r i c mood, a h i s t o r y of po o r a p p e t i t e and w e i g h t loss, d e l u s i o n s of self-b l a m e ,

h o p e l e s s n e s s , a n d p h y s i c a l i l l - h e a l t h i d e n t i f i e d t h o s e p a t i e n t s s u f f e r i n g f r o m c o g n i t i v e i m p a i r m e n t c a u s e d by d e p r e s s i o n . T h e t w o - y e a r f o l l o w - u p c o n f i r m e d the i n i t i a l d i a g n o s i s w i t h 92% (12/13) of t h o s e p a t i e n t s d i a g n o s e d as i r r e v e r s i b l y d e m e n t e d e v i d e n c i n g d e t e r i o r a t i o n in c o g n i t i v e f u n c t i o n i n g , w h i l e 88% (14/16) of t h o s e d i a g n o s e d as d e p r e s s e d e v i d e n c e d i m p r o v e m e n t in c o g n i t i v e f u n c t i o n i n g to w i t h i n t h e n o r m a l range. An a s s e s s m e n t of o v e r a l l level of c o g n i t i v e f u n c t i o n i n g m a y also a s s i s t w i t h t h e d i f f e r e n t i a l d i a g n o s i s of d e m e n t i a vs. d e p r e s s i o n . Folstein, Folstein, and M c H u g h (1975)

r e p o r t e d th a t p a t i e n t s w i t h a d i a g n o s i s o f p r o g r e s s i v e

o u t of a m a x i m u m of 3 0 points) on the M i n i - M e n t a l S t a t e E x a m (MMSE; a b r i e f s c r e e n i n g of v a r i o u s c o g n i t i v e f u n c t i o n s i n c l u d i n g o r i e n t a t i o n , attention, memory, a r d c o n s t r u c t i o n a l a b i l i t i e s ) . P a t i e n t s w i t h d e p r e s s i o n a n d c o g n i t i v e i m p a i r m e n t p e r f o r m e d s i g n i f i c a n t l y b e t t e r ’ b u t s c o r e s w e r e s t i l l in t h e i m p a i r e d range (M = 19.0, S . D.= 6.6). P a t i e n t s w i t h u n c o m p l i c a t e d d e p r e s s i o n p e r f o r m e d best (M =* 25.1, S . D . - 5.4) and w e r e n o t s i g n i f i c a n t l y d i f f e r e n t f r o m a n o r m a l e l d e r l y c o n t r o l g r o u p (M= 27.6, S . D.= 1.7). An a n a l y s i s w i t h a g e - m a t c h e d s a m p l e s s h o w e d a s i m i l a r p a t t e r n of r esults, Further, scores of d e p r e s s e d p a t i e n t s w i t h c o g n i t i v e i m p a i r m e n t i m p r o v e d s i g n i f i c a n t l y f o l l o w i n g t r e a t m e n t w i t h a n t i d e p r e s s a n t m e d i c a t i o n . S c o r e s o f the u n c o m p l i c a t e d d e p r e s s e d g r o u p a l s o i m p r o v e d f o l l o w i n g t r e a tment, a l b e i t to a s m a l l e r b u t s t i l l s t a t i s t i c a l l y s i g n i f i c a n t degree. T h e r e w a s no c h a n g e in t h e d e m e n t e d g r o u p over the sa m e o n e m o n t h t i m e interval.

W h i l e o v e r a l l l e vel of c o g n i t i v e f u n c t i o n i n g is an i m p o r t a n t variable, s o m e g l o b a l m e a s u r e s of f u n c t i o n i n g y i e l d a h i g h r a t e of f a l s e - n e g a t i v e d i a g n o s t i c errors, p a r t i c u l a r l y in i n d i v i d u a l s in t h e e a r l y s t a g e s of d e m e n t i a (i.e., p a t i e n t s in t h e e a r l y st a g e s of d e m e n t i a m a y be m i s c l a s s i f i e d as c o g n i t i v e l y i n t a c t ) . T h e r e s u l t s of su c h e x a m i n a t i o n s s h o u l d t h e r e f o r e be i n t e r p r e t e d C a u t i o u s l y and d i a g n o s e s d e t e r m i n e d o n l y w h e n r e s u l t s are U s e d in c o n j u n c t i o n w i t h a m o r e e x t e n s i v e a s s e s s m e n t of c o g n i t i v e

20 a b i l i t i e s . 2 • N e u r o p s y c h o l o g i c a l V a r i a b l e s C e r t a i n p a t t e r n s of p e r f o r m a n c e on v a r i o u s n e u r o p s y c h o l o g i c a l t e s t s h a v e b e e n p r o p o s e d as c h a r a c t e r i s t i c of d e m e n t e d a n d d e p r e s s e d popu l a t i o n s . a . P a t t e r n of P e r f o r m a n c e on the W e c h s l e r s c a l e s : F u 1d (1984) f o u n d t h a t a s p e c i f i c p r o f i l e of s u b t e s t s c o r e s on t h e W e c h s l e r A d u l t I n t e l l i g e n c e S c a l e (WAIS) i d e n t i f i e d 44% of the p a t i e n t s in the s t u d y w i t h A D and only 7% of a n o n - A D d e m e n t i a c o n t r a s t g r o u p s (i.e., M I D and "other d e m e n t i a s " ) . T h e p r o f i l e is A>B>C<D, A>D, w h e r e A - m e a n of a g e - c o r r e c t e d s c a l e d s c o r e s >n I n f o r m a t i o n a n d Vocabu l a r y , B « m e a n of S i m i l a r i t i e s a n d D i g i t Span, C = m e a n o f D i g i t Symbol and B l o c k Design, a n d D *= O b j e c t A s s e m b l y s c a l e d score. B r i n k m a n a n d B r a u n (1984) f o u n d t h i s p r o f i l e in 56% of A D p a t i e n t s a n d on l y 5% of M I D p a t i e n t s . F u r t h e r w o r k w i t h the W e c h s l e r s c a l e s a l s o s u p p o r t e d t h e low p r e v a l e n c e rate of th i s

p a t t e r n in n o r m a l e l d e r l y g r o u p s (Satz, Hynd, D'Elia,

Daniel, V a n Gorp, a n d Conner, 1990; Satz, Van Gorp, Soper, a n d M i t r u s h i n a , 1987; T u o k k o a n d Crockett, 1987) a n d e l d e r l y p s y c h i a t r i c p a t i e n t s (Tuokko, crockett, Hur w i t z , a n d Kozak, 1988). B e r n s t e i n , T e rmeer, L o n g brake, Heger, a n d N o r t h

(1989) f o u n d t h i s p r o f i l e in o n l y 16% of d e p r e s s e d e l d e r l y a n d M a r c o p u l o s and G r a v e s (1990) found it in o n l y 3. 7 %

thus a p p e a r s to h a v e some v a l u e in d i s c r i m i n a t i n g A D p a t i e n t s fr o m d e p r e s s e d patients, h o w e v e r its use in

d i s c r i m i n a t i n g d e p r e s s e d and n o n - A D d e m e n t e d p a t i e n t s has not be e n i n v e s t i g a t e d as of yet. b. L a n g u a g e : D i f f e r e n c e s in v e r b a l o u t p u t h a v e be e n n o t e d in d e p r e s s e d a n d d e m e n t e d patie n t s . W e i n g a r t n e r and S i l v e r m a n (1984) r e p o r t e d th a t on v e r b a l f l u e n c y t a s k s d e p r e s s e d p a t i e n t s p e r f o r m e d w i t h i n n o r m a l li m i t s u n d e r b o t h p h o n e t i c a l l y and s e m a n t i c a l l y - c u e d c o n d i t i o n s , and w e r e r e l a t i v e l y b e t t e r w h e n p r o v i d e d w i t h s e m a n t i c cues. D e m e n t e d patients, however, w e r e s i g n i f i c a n t l y less p r o d u c t i v e on both t a s k s t h a n d e p r e s s e d or c o n t r o l groups, and w e r e p a r t i c u l a r l y p o o r w h e n p r o v i d e d w i t h s e m a n t i c cues. c. M e m o r y : i m p a i r e d m e m o r y is c o m m o n in b o t h d e m e n t e d and d e p r e s s e d e l d e r l y patients. M e m o r y c o n s i s t s of t h r e e f u n d a m e n t a l c o g n i t i v e p r o c esses: 1) a c q u i s i t i o n / e n c o d i n g (i.e., g e t t i n g n e w i n f o r m a t i o n into me m o r y ) , 2) r e t e n t i o n (i.e., m a i n t a i n i n g or k e e p i n g t h a t i n f o r m a t i o n in m e m o r y for a p r o l o n g e d p e r i o d of time), a n d 3) r e t r i e v a l (i.e.,

r e c a l l i n g t h e i n f o r m a t i o n at a l ater time) (Caine, 1986) . It has b e e n h y p o t h e s i z e d t h a t d e m e n t e d a n d d e p r e s s e d i n d i v i d u a l s d o p o o r l y on m e m o r y t a s k s for d i f f e r e n t r e a s o n s ; t h a t is, t h a t d e f i c i e n c i e s in d i f f e r e n t n e u r o p s y c h o l o g i c a l m e c h a n i s m s a f f e c t t h e a c q u i s i t i o n / e n c o d i n g , r e t e n t i o n , a n d r e t r i e v a l a b i l i t i e s of t h e s e groups. W e i n g a r t n e r a n d c o l l e a g u e s p e r f o r m e d a s e r i e s of

s t u d i e s in a n a t t e m p t to d e l i n e a t e q u a l i t a t i v e f e a t u r e s that, d i s t i n g u i s h m e m o r y i m p a i r m e n t in d e p r e s s i o n f r o m m e m o r y

i m p a i r m e n t in p r o g r e s s i v e dementia. T h e i r w o r k s u g g e s t e d d e f i c i e n c i e s in d i f f e r e n t m e c h a n i s m s u n d e r l y i n g the

a c q u i s i t i o n / e n c o d i n g process.

W e i n g a r t n e r , Cohen, et al. (1981) f ound t h a t d e p r e s s e d p a t i e n t s d e m o n s t r a t e d l e a r n i n g and m e m o r y f a i l u r e s on t a s k s t h a t l a c k e d an o b v i o u s int e r n a l structure, and on tasks w h e r e t h e p a t i e n t w a s r e q u i r e d t o i m p o s e o r g a n i z a t i o n i n d e p e n d e n t l y f o r e f f e c t i v e l e a r n i n g a n d m e m o r y to take place. For example, d e p r e s s e d p a t i e n t s and c o n t r o l s m a t c h e d f o r age a n d e d u c a t i o n w e r e s i m i l a r in t h e i r a b i l i t y to f r e e l y r e c a l l a list o f organized, s e m a n t i c a l l y - r e l a t e d wor d s ; h owever, d e p r e s s e d p a t i e n t s p e r f o r m e d s i g n i f i c a n t l y m o r e p o o r l y w h e n a s k e d to r e c a l l a li s t of u n o r g a n i z e d , u n r e l a t e d words. T h e a u t h o r s i n t e r p r e t e d t h i s f i n d i n g as r e f l e c t i n g t h e d e p r e s s e d patie n t s ' a b i l i t y to t a k e a d v a n t a g e of cu e s a n d o r g a n i z a t i o n to aid t h e e n c o d i n g process. In the a b s e n c e of su c h e x t e r n a l cues, however, the t a s k b e c a m e m o r e e f f o r t f u l a n d t h e d e p r e s s i v e s ' p e r f o r m a n c e d e t e r i o r a t e d . F u r t h e r w o r k by C o h e n et al. (1982) d e m o n s t r a t e d t h a t m e m o r y a n d m o t o r i m p a i r m e n t s in d e p r e s s i o n w e r e m o s t a p p a r e n t on t a s k s t h a t r e q u i r e d s u s t a i n e d effort.

In c o n t r a s t to t h e a b o v e findings, W e i n g a r t n e r , Kaye, Sm a llberg, Ebert, Gillin, and S i t a r a m (1981) f o und t h a t p a t i e n t s s u f f e r i n g f r o m a p r o g r e s s i v e i d i o p a t h i c d e m e n t i a

(probably of an A l z h e i m e r type) c o u l d not u s e e x t e r n a l l y p r o v i d e d o r g a n i z a t i o n and s e m a n t i c c u e i n g t o aid encoding. R e c a l l of s e m a n t i c a l l y r e l a t e d w o r d s a n d r a n d o m w o r d s w e r e b o t h po o r in c o m p a r i s o n to a h e a l t h y c o n t r o l group. D e m e n t i a p a t i e n t s r e m e m b e r e d a b o u t t h e same n u m b e r of r a n d o m and r e l a t e d w o r d s a f t e r a s i n g l e p r e s e n t a t i o n a n d a f t e r r e p e a t e d p r e s e n t a t i o n s . In t h e s e patients, e n c o d i n g W a s n o t f a c i l i t a t e d by o r g a n i z a t i o n , s e m a n t i c cues, or r e p e t i t i o n . T h e a u t h o r s c o n t e n d e d that t h e i n f o r m a t i o n w a s w e a k l y e n c o d e d a n d t h e r e f o r e e a s i l y f o r g o t t e n u n d e r all conditions. W e i n g a r t n e r and c o l l e a g u e s (Cohen, et al., 1982;

W e i n g a r t n e r et al., 1977; W e i n g a r t n e r , et al., 1984;

W e i n g a r t n e r , Cohen, et al., 1981; W e i n g a r t n e r , Kaye, et al., 1981) a t t r i b u t e d the d i f f e r e n c e s in p e r f o r m a n c e in d e p r e s s e d a n d d e m e n t e d p a t i e n t s to d y s f u n c t i o n of d i f f e r e n t c o g n i t i v e m e c h a n i s m s . T h e y p r o p o s e d a " c e n t r a l m o t i v a t i o n a l d e f i c i t " in d e p r e s s i o n t o e x p l a i n t h e m e m o r y d y s f u n c t i o n e x p e r i e n c e d by t h e s e patients. C o g n i t i v e i m p a i r m e n t in d e p r e s s e d p a t i e n t s was le s s e v i d e n t on "easier" c o g n i t i v e t a s k s t h a t i n v o l v e d r e l a t i v e l y aut o m a t i c , effort l e s s , or p a s s i v e o p e r a t i o n s , and was m o r e e v i d e n t o n t a s k s r e q u i r i n g e f f o r t f u l e n c o d i n g a n d r e t r i e v a l a c t i v i t i e s . D e m e n t i a patients, however, f a i l e d t o p r o c e s s i n f o r m a t i o n e f f e c t i v e l y on all t a s k s d e s p i t e t h e p r e s e n c e of cues a n d o r g a n i z a t i o n a l aids, and t h e i r a p p a r e n t m o t i v a t i o n to do w e l l and s u s t a i n e d e f f o r t w h e n c o m p l e t i n g tasks. T h e m e m o r y i m p a i r m e n t in