PATIENTS AND MEMORY-IMPAIRED OLDER ADULTS
B.Sc.,, Ponctificia Universidade Catolica, Sao Paulo, Brasil, 1984
M •S c i , University of Victoria, Canada, 1987 A DISSERTATION SUBMITTED IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY
in the Department of
Psychology
We accept this as conforming to the required standard
Dr. Roger E. Graves
D r . M ic h a e 1! ‘fToschko DENISE DIAS CORREA
a c c e p t e d
_
FACULTY OF GRADUATE S T U D IE S
Dr. Louis D. CosuaDr. Donald W. Knowles
Dr. Allen R. Dobbs
©
c) DENISE DIAS CORREA, 1992 University of VictoriaAll rights reserved. This dissertation may not be reproduced in whole or in part, by mimeograph or other means, without the permission of the author.
Supervisor: Professor Roger Graves
ABSTRACT
Disturbances in awareness of memory deficit have been observed in Alzheimer's disease (AD), yet few studies have s ystematically investigated the phenomena in this population. The present study has applied the concepts and instruments used in the metamemory literature to the study of awareness of memory deficit in twenty mild AD patients, eighteen individuals with, memory impairment, and eighteen normal elderly controls. Specifically, a multidimensional approach to metamemory was selected including an evaluation of perception of m e m o r y change, knowledge about memory functioning, and self-monitoring of m e m o r y performance. Consistent with previous research, AD patients reported less change in memory functioning than did their informants, suggesting that these patients have diminished awareness of the extent of the decline in their m emory abilities. No differences among the three groups were observed in self-report measures addressing the use
of strategies, perception of control over memory functioning, and presence of anxiety in m e m o r y-related activities. Diminished self-monitoring abilities were observed in the AD patients' tendency to make a high number of intrusion errors with few self-corrections, and
to overestimate their performance on memory t e s t s , The results also suggest that relatives' evaluation of memory functioning may be p a r ticularly useful in differentiating AD patients from older adults displaying memory impairment and from normal elderlv.
D r , R E . Graves
Dr. Louis b. CoSta
D r . Micha'el Joschko
Dr. Donald W. Knowles
TABLE OF CONTENTS TITLE P A G E ... i A B S T R A C T i i TABLE OF C O N T E N T S ... . ... iv LIST OF T A B L E S . . ... vi LIST 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... . X I N T R O D U C T I O N . 1 Alzheimer • s Disease. ... 3 " N o r mal"Aging. ... .17 Ag e-Related Memory D e f i c i t s ... 21 Awareness/UnawareneSs of Memory F u n c t i o n i n g . ...28 Self-Report Q u e s t i o n n a i r e s ... 39 Monitoring of Memory P e r f o r m a n c e . ... .46 Purpose of the S t u d y ... 50 Expected F i n d i n g s ... .53 M E T H O D ______ 55 S u b j e c t s ... 55
Description of Measures and P r o c e d u r e ...58
Screening P r o c e d u r e ... .58
Neuropsychological Test B a t t e r y . ... 59
Estimation of P e r f o r m a n c e . ... 60
Modified M I A Q u e s t i o n n a i r e . ... 61
Intrusion Errors and S e l f - C o r r e c t i o n s ... .64
RESULTS. . . . , . ...■'»... .69
Demographic and. Psychometric Variables. ... 69
MIA Scales R e l i a b i l i t y . ... 76
M I A Scales-Overall Analyses. ...76
Perception of Memory Change/Memory P e r f o r m a n c e , ,.79 Estimation of P e r f o r m a n c e ... .86
I ntrusion E r r o r s ... 89
S e l f - C o r r e c t i o n s . ... 94
D I S C U S S I O N ... -... 98
Report of Memory C h a n g e ... 98r R eport of Strategy Use, Locus of Control, and A n x i e t y . , , . ... 108
S e l f - M o n i t o r i n g . ... . 112
D emographic and Psychometric V a r i a b l e s . ...126
Summary and C o n c l u s i o n s ...131
R E F E R E N C E S ... ...131
APPENDICES. . ... 154
Appendix A - Performance E v a l u a . ... 154
Appendix B - M o d ified MIA Q u e s t i o n n a i r e . . , 156
A p p e n d i x C - M o d ified MIA Questionnaire: Re l a t i v e / C a r e g i v e r ... 170
LIST OF TABLES
Table 1. Statistics for Demographic and Psychometric Variables (3 G r o u p s ) . . . ... . .71 Table 2. AD Subjects Characteristics A c c o r d i n g to
S o u r c e .... ... .. u ... 7 3 Table 3. Subjects Characteristics (4 G r o u p s ) ... ...75 Table 4. Modified MIA Questionnaire Reliability
(Cronbach's A l p h a ) ... 77 Table 5. Group Comparisons on the Modified M I A
Questionnaire S c a l e s ... , ... 81 Table 6 . Correlations Between Change Scale
Discrepancy Score and Demographic and Psychometric Variables for the AD
G r o u p ... » ... 85 Table 7, Correlations Between Intrusions and
Psychometric Variables for the AD
Figure 1. Means and SEM for the M I A questionnaire
Scales . ... ... 80
Figure 2. Means and SEM for the change-self vs.
Change<Care Discrepancy S c o r e . ., . . ... 83 Figure 3. Distribution of scores on the Buschke
Delayed Recall and Change-Self S c a l e ... 87 Figure 4. Distribution of Scores on the Buschke
Delayed Recall and Change-Care Scale.*.* 88 Figure 5. Average Number and SEM for Mispostdictions
Across G r o u p s ... 90
Figure 6 . Means and SEM for Intrusion Types
Across G r o u p s ... 92
Figure 7. Means and SEM for Self-Correction Types
Across G r o u p s ... ... 95
Figure 8 . Proportion and SEM for Acknowledged and Corrected Intrusion Errors Across
ACKNOWLEDGMENTS
Many people have contributed to the completion of this dissertation either directly or indirectly. While I cannot mention each one of them by name, I acknowledge the participation of each one of these people.
I would like to thank Dr. Roger Graves for his support throughout the various stages of the execution of this project, as well as during all my years as a graduate student. I thank Dr. Donald Knowles, Dr. Michael jfoschko, and Dr. Roger Dixon for their interesting and helpful suggestions. I am particularly grateful to Dr. Louis Costa for his interest, attention, and invaluable contributions not only to the completion of this dissertation but also to my professional development.
I thank Dr. Sean Haldane, Dr. Duncan Robertson, Dr. Holly Tuokko, and Dr. Kathy Montgomery for helping me in my relentless search for individuals with mild Alzheimer's disease. I would also like to mention Pat Konkin, Richard Chadwick, and Brian Roth who saved m e from all my "statistical panic attacks" and contributed significantly to my understanding of this area.
Last but definitely not least, I am very grateful to my whole family, particularly to m y mother Florence Roberts and to m y grandmother Beatriz B. Correa, for their
unconditional love, dedication,- and support for anything (and everything) I have ever wanted to accomplish.
DEDICATION
This dissertation is dedicated to a very special person, m y uncle Renato, who left me with the happiest and most beautiful memories of my childhood.
D i s t u r b a n c e s in awareness of d e f i c i t (i.e., anosognosia) have been observed in several
n e u r o p s y c h o l o g i c a l syndromes like h e m i p l e g i a
(Weinstein & Kahn,, 1955), A n t o n ’s syndr o m e (Bisiach, Vallar, Perani, papagno, & Berti, 1986), h e m i a n o p s i a
(Koehler, Endtz, Tevelde, and Hekster, 1986), head i njury (Prigatano, 1986), aphasia (Weinstein, nyerly, Cole, & Czer, 1966), amnesia (Victor, A d a m s & Collins, 1977)., and d e m e n t i a ( Frederiks, 1985), The term a n o s o g n o s i a w a s i n t r o d u c e d by B a b i n s k i (;*<■> 1.4 ) to d e s c r i b e lack of knowledge, aware n e s s or r e c o g n i t i o n of disease. The terms u n a w a r e n e s s of deficit,
anosognosia, and lack of insight are used
i n t e r c h a n g e a b l y in this study to d e s c r i b e p a t i e n t s who lack a w a r e n e s s of a n e u r o p s y c h o l o g i c a l deficit.
A l t h o u g h the study of these n e u r o p s y c h o l o g i c a l s y n d r o m e s has p r o v i d e d r e l e v a n t i nformation conce r n i n g t h e n a t u r e of awareness, system a t i c n e u r o p s y c h o l o g i c a l i n v e s t i g a t i o n s of p h e n o m e n a l a w a r eness are few
(Schacter, 1990). Additionally, m a n y of the e x i sting s t u d i e s are b a s e d on clinical o b s e r v a t i o n s w i t h little i n f o r m a t i o n r e g a r d i n g b o t h the d e f i n i t i o n of c o n cepts
a nd the c r i t e r i a u s e d to assess u n a w a r e n e s s (McGlynn & SChacter, 1,989) .
The fact t h a t b r a i n d a m a g e d p a t ients m a y be u n a w a r e of their defic i t s is i m p o r t a n t for both t h e o r e t i c a l and clinical reasons. T h e study of u n a w a r e n e s s can p r o v i d e i n f o r m a t i o n a bout t h e
m e c h a n i s m s that n o r m a l l y a l l o w indivi d u a l s to be aware and to m o n i t o r their c o g n i t i v e functioning.
Clinically, u n a w a r e n e s s of d e f i c i t can be a c o n s i d e r a b l e o b s t a c l e for the a c h i e v e m e n t of
s u c c e s s f u l r e h a b i l i t a t i o n of function. P a t i e n t s who are u n a w a r e of their d e f i c i t s are less likely to
b e n e f i t from or p a r t i c i p a t e in r e m e d i a l interventions, or to function e f f i c i e n t l y in e v e r y d a y life.
Similarly, these patie n t s m a y insist on p e r f o r m i n g a c t i v i t i e s that they are no longer c a p a b l e o f .
U n d e r s t a n d i n g t h e a w a r e n e s s d i s t u r b a n c e m a y also help c a r e g i v e r s to p r e p a r e for and to deal w i t h t h e p a t i e n t in a m o r e e f f i cient manner. The p r e s e n t r e s e a r c h f o c u s e s on t h e s t u d y of a w a r e n e s s of d e f i c i t in p a t i e n t s with A l z h e i m e r ' s d i s e a s e (AD) as well as in i n d i v i d u a l s e x p e r i e n c i n g a g e - r e l a t e d m e m o r y deficits. Specifically, it ad d r e s s e s issues c o n c e r n i n g d e g r e e of a w a r e n e s s of m e m o r y i m p a i r m e n t in these populations. A d e s c r i p t i o n
of AD, r e c e n t r e s e a r c h a d d r e s s i n g "normal aging" and a g e - r e l a t e d c o g n i t i v e impairments, as well as the most r e l e v a n t m e m o r y deficits d i s p l a y e d b y these
i n d i v i d u a l s is followed b y a d i s c u s s i o n of c u r r e n t fi n d i n g s r e g a r d i n g a w a r e n e s s of m e m o r y f u n c t i o n i n g in cl i n i c a l and normal populations. Finally, a
s y s t e m a t i c a p p r o a c h for i n v e s t i g a t i n g a w a r e n e s s of m e m o r y d e f i c i t is proposed.
A l z h e i m e r ' s d i s e a s e
D e m e n t i a is g e n e r a l l y d e f i n e d as a 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 of s u f f i c i e n t s e v e r i t y to ca u s e a r e s t r i c t i o n in n o rmal activities. At least t h r e e o f the f o l l o w i n g areas are affected: memory, v i s u o s p a t i a l skills, language, judgement, abstraction, a n d p e r s o n a l i t y (Cummings & Benson, 1983). T h e
d i a g n o s t i c c r i t e r i a p r o p o s e d by the D i a g n o s t i c and S t a t i s t i c a l M a n u a l of M e n t a l D i s o r d e r s - R e v i s e d (DSM III-R; 1987), a l t h o u g h c o n s i s t e n t w i t h the above
m e n t i o n e d definition, give p a r t i c u l a r e m p h a s i s to m e m o r y d e c l i n e and r e q u i r e the p r e s e n c e of an
et i o l o g i c a l factor.
A m o n g t h e dementias, A D is the m o s t well s t udied a n d a c c ounts for the p l u r a l i t y of the d e m e n t i a cases
th e r e l a t i v e p r e v a l e n c e of d e m e n t i a a mong p a t ients r e f e r r e d for e v a l u a t i o n of p r o g r e s s i v e i n t e l l e c t u a l d e t e r i o r a t i o n the m o s t frequent d i a g n o s e s were: (1) AD
(39%), (2) m u l t i - i n f a r c t d e m e n t i a (13%), (3)
m i s c e l l a n e o u s or n o n - s p e c i f i c d e m e n t i a (11%), (4) a l c o h o l i c d e m e n t i a (8 %), and (5) d e m e n t i a a s s o c i a t e d w i t h p s y c h i a t r i c d i s o r d e r (7%) .
The d i a g n o s i s of A D is based on c l i n i c a l and
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 and c u r r e n t l y c a n n o t be d e t e r m i n e d by the use of r o u t i n e n o n - i n v a s i v e
l a b o r a t o r y tests (e.g., CT Scan, E E G ) . T h e s y n d r o m e is c h a r a c t e r i z e d by an insidious Onset w i t h
p r o g r e s s i v e m e m o r y and o tner cognitive d e f i c i t s (e.g., language, praxis, p r o b l e m solving, social functioning) m o s t o f t e n after age 65. T h e d i a g n o s i s e x c l u d e s
d i s t u r b a n c e s of c o n s c i o u s n e s s and other s y s t e m i c or b r a i n d i s e a s e s that could a c c o u n t for t h e p r o g r e s s i v e
i n t e l l e c t u a l deterioration. The 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 i c a l and
C o m m u n i c a t i v e D i s o r d e r s and Stroke (NINCDS) a n d the 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 r d e r s A s s o c i a t i o n
(ADRDA) have s p e c i f i e d the d i a g n o s t i c c r i t e r i a by
s u b d i v i d i n g it into Probable, P o s s i b l e a n d D e f i n i t e AD (McKhann, Drachman, Folstein, Katzman, Price, &
Stadlan, 1984). T h e criteria for P r o b a b l e A D is c o n s i s t e n t w i t h the above m e n t i o n e d description. P o s s i b l e AD m a y be d i a g n o s e d in the p r e s e n c e of v a r i a t i o n s in the onset, presentation, or c l i nical course. A d d itionally, syste m i c or b r a i n d i s eases may b e e v i dent as long as they ate not c o n s i d e r e d the c ause of the d e m e n t i a „ C r i t e r i a for t h e d i a g n o s i s of d e f i n i t e AD i n c ludes d i a g n o s i s of P r o b a b l e AD
a c c o m p a n i e d by h i s t o p a t h o l o g i c e v i d e n c e from b i opsy or autopsy.
Th e p r o g r e s s i v e i n t e l l e c t u a l d e t e r i o r a t i o n that o ccurs in AD can be d i v i d e d in three stages (Cummings & Benson, 1983). M e m o r y i mpairment is among the
e a r l i e s t and m o s t p r o m i n e n t features. The d e f i c i t s are c h a r a c t e r i z e d by r e d u c e d ability t o learn new m a t e r i a l and d i f f i c u l t y r e c a l l i n g r e m o t e inform a t i o n w h i c h b e c o m e i n c r e a s i n g l y m o r e severe as the d i s e a s e progresses. V i s u o s p a t i a l s kills are also impaired early in the c o u r s e of AD w i t h e v i d e n c e of t o p o g r a p h i c d i s o r i entation, p o o r c o n s t r u c t i o n s a n d spatial
disor i e n t a t i o n . The first signs of l a n g u a g e
a b n o r m a l i t i e s are impai r e d W o r d - f i n d i n g and e m p t iness of s p o n t a n e o u s s p e e c h (e.g., c i r c u m locution), These d e f i c i t s u s u a l l y d e v e l o p into anomie, p a r a p h a s i a and
u s u a l l y o b s e r v e d in the second stage. A l t h o u g h
p e r s o n a l i t y and s o cial b e h a v i o r r e m a i n intact d u r i n g the e arly phases, t h e r e is some e v i d e n c e of a pathy and lack of insight, d e p r e s s i o n m a y o c c u r early in the co u r s e of the illness but it is u s u a l l y not s e v e r e and it often r e c e d e s as t h e intell e c t u a l d e t e r i o r a t i o n worsens. The later stages of the illness are
c h a r a c t e r i z e d by severe d e t e r i o r a t i o n of i n t e l l e c t u a l f u n c t i o n s a s s o c i a t e d V/ith m o t o r and n e u r o l o g i c a l
abnormalities. However, AD is not a h o m o g e n e o u s
d i s o r d e r w i t h a single set of stages or p a t t e r n s that d e s c r i b e it, since c o n s i d e r a b l e v a r i a b i l i t y in the p r e s e n t a t i o n of c o g n itive d e f i c i t s is o ften reported.
The d i a g n o s i s of AD can be c o n f i r m e d o n l y by h i s t o p a t h o l o g i c evidence of e x c e s s i v e n u m b e r s of n e u r o f i b r i l l a r y t a ngles and s enile p l a q u e s in the ce r e b r a l c o r t e x (e.g./ temporal, p a r i e t a l a n d frontal areas) and g r a n u o v a c u l a r d e g e n e r a t i o n in the
h i p p o c a m p u s (Blessed, Tomlinson, & Roth, 1968; Chui, 1989). A l t h o u g h d e c r e a s e d b r a i n weight, loss of neurons, g yral atrophy, v e n t r i c u l a r dilation, and n e u r o f i b r i l l a r y tangles are p r o m i n e n t a g e - r e l a t e d changes, there is a m a r k e d increase in t h e s e changes, p a r t i c u l a r l y in the d e n s i t y and e x t e n t of d i s t r i b u t i o n
of tangles, in d e m entia p a t i e n t s (Kemper, 1984) .
Specifically, the d e v e l o p m e n t of n e u ritic p l a q u e s and n e u r o f i b r i l l a r y t a n gles in the limbic s y s t e m ( i . e . , a m y g d a l a and hippocampus) h a v e been s u g g e s t e d to be r e s p o n s i b l e for some of the m e m o r y d e f icits o b s e r v e d in the early stages of A P (Hyman, Van Hoesen, &
Damasio, 1985; Hyman, Kramer, & Van Hoesen, 1987). Similarly, n e u r o f i b r i l l a r y d e g e n e r a t i o n in m u l t i m o d a l a s s o c i a t i o n c o r t e x (temporo-parietal-occipit al)
a p p e a r s to be r e l a t e d to aphasia, apraxia and agnosia.
S u b c o r t i c a l areas like t h e c h o l i n e r g i c basal forebrain, n o r a d r e n e r g i c locus ceruleus and
s e r o t o n e r g i c r a p h e n u c l e u s are also a f f e c t e d but t h e i r s p e c i f i c c o n t r i b u t i o n s are still unclear. T h e r e has been, however, some i n d i c a t i o n that the m e m o r y
d e f i c i t s in A D (Rossor, Emson, Mountjoy, Roth, & Iversen, 1982; H u p p e r t & Kopelman, 1989) and in
no r m a I" a g i n g (Bartus, Dean, Beer, & Lippa, 1982 ; Mann, Yates, & Marcyniuk, 1984) are r e l a t e d to the
c h o l i n e r g i c d e f i c i e n c y o f t e n o b s e r v e d in t h e s e
individuals. Specifically, c h o l i n e r g i c d e f i c i e n c y in A D has bean linked to cell loss and tangles in the n u c l e u s b a s a l i s w h i c h h a s d i f f u s e c h o l i n e r g i c
forebrain) and the h i p p o c a m p u s (Whitehouse, P r i c e , Struble, Clark, Coyle, & DeLong, 1982) .
M o s t s t u d i e s e x a m i n i n g p a t terns of c e r ebral gl u c o s e m e t a b o l i s m (e.g., G r a d y et al., 1990) and ce r e b r a l b l o o d flow (e.g., Prohovnik, Mayeux, & Sackeim, 1985) in AD have r e p o r t e d g l u cose
h y p o m e t a b o l i s m and r e d u c e d blood flow m o s t l y in the p a r i e t a l and t e m poral areas. There a ppear to be, however, a s i g n i f i c a n t n u m b e r of p a t i e n t s s h o w i n g p r e d o m i n a n t l y frontal or p o s t e r i o r m e t a b o l i c
ab n o r m a l i t i e s (Haxby, et al., 1988). The b e h a v i o r a l c o r r e l a t e s of frontal involv e m e n t in A D h a v e not been t h e focus of s y s t e m a t i c research. The m o s t c o m m o n fi n dings a ppear to be apathy, i m p a i r e d insight, lack of judgement, p e r s e v e r a t i o n and i n e f f i c i e n t p r o b l e m s o l v i n g (Cummings & Benson, 1983).
T h e r e has been an i n c r e a s i n g interest in u n d e r s t a n d i n g the i n f o r m a t i o n p r o c e s s i n g d e f i c i t s u n d e r l y i n g the r e d u c e d a b i l i t y to a c q u i r e v e r b a l and n o n v e r b a l i n f o r m a t i o n f r e q u e n t l y o b s e r v e d in AD patients. I n v e s t i g a t i o n s u s i n g the c o n c e p t s of c o g n i t i v e n e u r o p s y c h o l o g y have d e m o n s t r a t e d i m p o r t a n t d i f f e r e n c e s in s u p e r f i c i a l l y s i milar m e m o r y dysfunctions. A d d itionally, a q u a l i t a t i v e a n a l y s i s of error p a t t e r n s c o m b i n e d w i t h s t a n d a r d i z e d q u a n t i t a t i v e
t h e c o g n i t i v e f a c t o r s involved in the o b s erved l e a rning i m p a i r m e n t s (Heindel, Salmon, & Butters, 1989) .
S h o r t - t e r m m e m o r y (or w o r k i n g memory) abilities a p p e a r to be i m p a i r e d in A D p a t i e n t s (Butters et al., 1988; Kopelman, 1985; M orris & Baddeley, 1988). a m o d e r a t e r e d u c t i o n in immediate m e m o r y span (e.g., d i g i t span, v i s u a l s p a n ) , a r e c e n c y e f f e c t on the r e c a l l of w o r d s and s u s c e p t i b i l i t y to d i s t r a c t i o n
(e.g., B r o w n - P e t e r s o n task) have been observed. A l t h o u g h t h e r e has b e e n some s u g g e s t i o n t h a t these d i f f i c u l t i e s are s e c o n d a r y to i m p a i r e d a t t e n t i o n to i n c o m i n g s t i m u l i (Wilson et al. 1983), a l t e r n a t e views h a v e b e e n proposed. R e c e n t studies a d d r e s s i n g
a t t e n t i o n a l p r o c e s s e s in A D (Gallie, T u o k k o & Graf, 1991; K a s z n i a k & Davis, 1986; Storandt, Botwinick, & Danziger, 1986) r e p o r t e d that a t t e n t i o n d e c l i n e is not d e t e c t a b l e u n t i l the dementia has r e a c h e d m o d e r a t e to s e v e r e levels. M o r r i s and K o p e l m a n (198 6 ) have
s u g g e s t e d that the s h o r t - t e r m m e m o r y d e f i c i t s o b s e r v e d in A D m i g h t be r e l a t e d to a g e n e r a l i z e d inform a t i o n p r o c e s s i n g deficit.
R e c e n t i n v e s t i g a t i o n s (Butters, Granholm, Salmon, Grant, & Wolf, 1987; G r a n h o l m & Butters, 1988; H e i n d e l
et al. 1989) h a v e s u p p o r t e d the n o t i o n that e p i s o d i c a n d semantic m e m o r y are d i s t u r b e d in AD. T u l v i n g
(1 .-4 3 ) h a s d e s c r i b e d episodic m e m o r y as r e q u i r i n g
c o n s c i o u s r e c o l l e c t i o n of the t e m p o r a l - s p a t i a l c o ntext in W h i c h the e v e n t occurred. S e m a n t i c memory, on the other hand, r e q u i r e s the r e t r i e v a l of i n f o r m a t i o n
(i.e., g e n e r a l knowledge) w i t h o u t its t e m p o r a l - s p a t i a l context. It h a s been p r o p o s e d that t h r o u g h r e p e t i t i o n a n d overlearning, m e m o r i e s that are i n i t i a l l y e p i sodic m a y b e c o m e c o n t e x t free and part of t h e i n d i v i d u a l ' s S e m a n t i c k n o w l e d g e (Heindel et al. 1989) .
Several s t u dies (Butters, 1985; Cushman, Como, Booth, & Caine, 1988; M a r t i n & Fedio, 1983;
W e i n g a r t n e r et al. 1983) have d e m o n s t r a t e d t h a t in d e m e n t i a both the a b ility to a c q u i r e i n f o r m a t i o n a s s o c i a t e d w i t h t e m p o r a l - s p a t i a l cues a n d to r e c a l l p r e v i o u s l y a c q u i r e d g e n e r a l k n o w l e d g e are impaired, o n tests that r e q u i r e the recall of s h o r t p a s s a g e s cr w o r d lists (i.e., m e a s u r e s of e p i s o d i c memory) AD p a t i e n t s d i s p l a y c o n s i d e r a b l e i m p a i r m e n t (B u t t e r s f Granholm, Salmon, Grant, & Wolf, 1987; Delis, Massman, Butters, Salmon, Cermak, & Kramer, 1991).
Furthermore,, t h e o b s e r v a t i o n that t h o s e patients' r e c o g n i t i o n m e m o r y is also i m p aired p r o v i d e d e v i d e n c e t h a t t h e r e is a d e f i c i t in l e a rning or e n c o d i n g
i n f o r m a t i o n (Delis et a l . , 1991; Kaszniak, 1986). M e m o r y i m p a i r m e n t is s e e n for b o t h v erbal and
n o n v e r b a l m a t e r i a l (Wilson, Kaszniak, Bacon, Fox, & Kelly, 1982), Furthermore, m i l d d e f i c i t s in the
a b i l i t y to r e c a l l r emote i n f o r m a t i o n w i t h no temporal g r a d i e n t (Wilson, Kaszniak, & Fox, 1981), and with less i n v o l v e m e n t of r e m o t e than of r ecent information
(Cummings & Benson, 1992).
A l t h o u g h A D p a t i e n t s d i s p l a y impairment in both t h e i m m e d i a t e and the d e l a y e d r e c a l l of information, t h e r e h a v e b e e n some d i s c r e p a n t findi n g s r e g a rding w h i c h of t h e s e two m e a s u r e s d i f f e r e n t i a t e s these p a t i e n t s m o r e accurately. For instance, Welsh,
Butters, Hughes, Mohs, & R e y m a n (1991) r e p o r t e d that- d e l a y e d r e c a l l m e a s u r e s w e r e p a r t i c u l a r l y s e n s i t i v e in d i s c r i m i n a t i n g e a r l y A D p a t i e n t s from e l d e r l y normal controls, even t h o u g h immediate r e call and r e c o g n i t i o n w e r e a l s o i m p a i r e d in AD. R e c o g n i t i o n m e m o r y and
i n t r u s i o n e r r o r s had the g r e a t e s t value in
d i s c r i m i n a t i n g b e t w e e n m o r e s e v erely d e m e n t e d groups. C o nversely, T u o k k o and c o l l e a g u e s (1989, 1991)
o b s e r v e d t h a t free recall m e a s u r e s were more useful t h a n d e l a y e d recall m e a s u r e s in t h e early d e t e c t i o n of AD. Finally, R o b i n s o n - W h e l e n & S t o r a n d t (1992)
r e p o r t e d that m i l d AD p a t i e n t s r e c a l l e d s i g n i f i c a n t l y less i n f o r m a t i o n than normal e l d e r l y both in i m m e d i a t e and d e l a y e d recall m e a s u r e s s u g g e s t i n g a d i s r u p t i o n of e n c o d i n g processes. In a m e t a - a n a l y t i c study
a d d r e s s i n g the d i f f e r e n t i a t i o n of d e m e n t i a from n ormal aging, Christensen, Hadzi-Pavlovic, & J a c o m b (1991) a r g u e d that a test's a b ility t o d i s c r i m i n a t e t h e s e two p o p u l a t i o n s m i g h t v a r y a c c o r d i n g to Stage of the
d e m e n t i n g illness.
It has also been s u g g e s t e d that AD patients' d e f i c i t s in the recall of i n f o r m a t i o n are c l osely a s s o c i a t e d w i t h i mpairments in u t i l i z i n g s e m antic i n f o r m a t i o n (i.e., cues) at e n c o d i n g and r e t r i e v a l
(Cushman, et al., 1988). F u r t h e r e v i d e n c e for i m p a i r e d semantic p r o c e s s i n g comes from tests of v e r b a l f l u e n c y in w h i c h A D p a t i e n t s o f t e n d i s p l a y a r e d u c t i o n in the a b ility to v e r b a l l y p r o d u c e e x e m p l a r s c o m p r i s i n g a b s t r a c t c a t e g o r i e s (e.g., c a t e g o r y f l u e n c y task) w h i l e their a b i l i t y to p r o d u c e words that b e g i n w i t h a c e r t a i n letter (e.g., letter f l u e n c y task) is less impaired. T h e s e findings indicated t h a c the
c a t e g o r y fluency t a s k is a h i g h l y s e n s i t i v e m e a s u r e of d e f i c i e n c i e s in semantic memory. On the other hand, since the letter fluency tasks can b e p e r f o r m e d U s i n g p h o n e m i c cues to s e arch for w o r d s i m p a i r m e n t s on this
t a s k m a y only be a p p a r e n t in later stages of the disease.
AD p a t i e n t s display, therefore, a p a t t e r n of d e f i c i t s in e p i s o d i c and semantic m e m o r y that d i f f e r e n t i a t e s them from p a t i e n t s w i t h other
n e u r o p s y c h o l o g i c a l syndromes. Additionally, their p e r f o r m a n c e is c h a r a c t e r i z e d by s e n s i t i v i t y to
p r o a c t i v e interference, p e r s e v e r a t i o n s and intrusion e r rors (Butters, 1985; B u t t e r s et al. 1987).
T h e r e is some c o n t r o v e r s y in t h e literature r e g a r d i n g the d e f i n i t i o n of intrusions. I n t r usion e r rors have b e e n g e n e r a l l y d e f i n e d as i n t r o d u c t i o n of u n r e l a t e d items w h i l e p e r f o r m i n g a g iven task (e.g., r e c a l l i n g a list o f w o r d s ) . I n t r u s i o n errors h a v e a l s o b e e n d e s c r i b e d as ''inappropriate r e c u r r e n c e of r e s p o n s e s from a p r e c e d i n g test item, test or
p r o c e d u r e " (Fuld, Katzman, Davies, & Terry, 198 2) w h i c h is also c o n s i s t e n t w i t h some d e f i n i t i o n s of p e r s e v e r a t i v e r e s p o n s e s (Sandson & Albert, 1984).
B u t t e r s and c o l l e a g u e s (1987) d e s c r i b e d p e r s e v e r a t i o n s as r e p e t i t i o n of a c o r r e c t word W i t h i n a g i v e n trial. S e v e r a l s t u dies (Brinkman, Largen, Cushman, Braun, & Block/ 1986; Fuld et al. 1982; Fuld, 1983; Kramer, Delis, Blusewicz, Brandt, Ober, & Strauss, 1988/ have d o c u m e n t e d t h e o c c u r r e n c e of i n t r u s i o n errors in AD
a nd have s u g g ested t h a t theSe errors are an impor t a n t c h a r a c t e r i s t i c of t h e syndrome.
Fuld and c o l l e a g u e s (1982) found an a s s o c i a t i o n b e t w e e n the o c c u r r e n c e of intrusion e r r o r s and the c h o l i n e r g i c d e f i c i e n c y o b s e r v e d in AD. Additionally, W i l s o n and c o l l e a g u e s (198 3) d i s t i n g u i s h e d b e t w e e n p r i o r - l i s t errors (items from p r e v i o u s l y p r e s e n t e d tests) and e x t r a - l i s t intrusions (items not p r e s e n t e d in the test s i t u a t i o n ) . T h e authors o b s e r v e d that AD p a t i e n t s m a d e p r e d o m i n a n t l y e x t r a - l i s t intrusions. This d i s t i n c t i o n has been s u g g e s t e d t o be r e l e v a n t since the p r e s e n c e of p r i o r - l i s t intrusions m a y be indica t i v e of some a b i l i t y to r e g i s t e r and e ncode inform a t i o n a s s o c i a t e d w i t h a r e t r i e v a l d e f i c i t w h i l e e x t r a - l i s t intrus i o n s may indic a t e an e n c o d i n g d e f i c i t
(Hart, Smith, & Swash, 1986).
Other studies (Gordon, Whitehouse, Cockrell, Mroz, & Steele, 1984; Ober, DronkerS,, Kbss, Delis, & Friedland, 1936; Shind l e r et al. 1984), however, did n o t find h i g h e r intrusion rates in AD p a t i e n t s w h e n c o m p a r e d to o ther d i a g n o s t i c g roups (e.g., c e r e b r a l v a s c u l a r accidents, aphasia, o t h e r d e m e n t i a s ) .
L o w e n s t e i n a n d c o l l e a g u e s (1989, 1991) also r e p o r t e d t h a t test intrusions did not d i s t i n g u i s h A D from other n e u r o l o g i c a l disorders. T h e authors observed,
however, t h a t t h e groups could be d i s c r i m i n a t e d a c c o r d i n g to s p e c i f i c types of intrusion errors. P a t i e n t s w i t h m i l d AD m a d e s i g n i f i c a n t l y m o r e
u n r e l a t e d intrusions (i.e., responses' u n r e l a t e d either to the t o - b e - r e m e m b e r e d t a r gets dr to the d i s t r a c t o r items) t h a n p a t i e n t s w i t h cerebral i n f a r c t i o n s or with d epression. T h e o c c u r r e n c e of u n r e l a t e d intrusions w e r e i n t e r p r e t e d as e v i d e n c e for (a) a failure in the s t o r a g e / c o n s o l i d a t i o n of i nformation since patients p e r f o r m e d p o o r l y on f r e e - r e c a l l and r e c o g n i t i o n measures, or (b) d i f f i c u l t i e s in s e l f - m o n i t o r i n g .
A l t h o u g h it has been s u g g ested that t h e m e c h a n i s m u n d e r l y i n g i n t r u s i o n errors in AD m a y be r e l a t e d
m a i n l y to d e f i c i t s in s h o r t - t e r m m e m o r y (Gordon et al., 1984; Lee, Loring, Flanigin, Smith, & Meador, 1988), t h e r e is some e v i d e n c e a g ainst this view.
First, low c o r r e l a t i o n s b e tween i ntrusions and either v e r b a l m e m o r y t e s t s or d e m e n t i a s e v erity h a v e been r e p o r t e d (Shindler, Caplar, & Hier, 1984). Second, p a t i e n t s w i t h H u n t i n g t o n ' s d i sease m a k e few intrusion e r r o r s d e s p i t e t h e i r m e m o r y d e ficit (Butters et al., 1987) . Furthermore, r e s e a r c h involving p a t i e n t s with W e r n i c k e ' s a p hasia indicates the o c c u r r e n c e of a high n u m b e r of intrusions in this p o p u l a t i o n (Marshall & Tompkins, 1982).
Sh i ndler and c b l l e a g u e s (1984) s u g g e s t e d t h a t in t r u s i o n errors o b s e r v e d in AD and W e r n i c k e ' s aphasia m a y be a c o n s e q u e n c e of d e f e c t i v e s e l f - m o n i t o r i n g
a b i l i t i e s since there is little i n sight into the illness in both of these conditions. A d d itionally, t h e o b s e r v a t i o n that i n t r usion errors are f r e q u e n t l y r e p o r t e d in K o r s a k o f f ' s d i s e a s e (Butters, 1985)
s u g g e s t s that t h e s e e rrors c a n n o t be a c c o u n t e d for by th e p r e s e n c e of language d i s t u r b a n c e s .
S e l f - m o n i t o r i n g a b i l ities h a v e b e e n i n v e s t i g a t e d in a p hasic subjects t h r o u g h an e v a l u a t i o n of their v e r b a l s e l f - c o r r e c t i v e b e h a v i o r (i.e., a b ility to r e c o g n i z e and c o r r e c t language p r o d u c t i o n e r r o r s ) . M a r s h a l l and T o m p k i n s (1982) r e p o r t e d that s u c c e s s f u l s e l f - c o r r e c t i v e a b i l ities w e r e r e l a t e d to s e v e r i t y of a p h a s i a and s u g g e s t e d that s e l f - c o r r e c t i o n s m a y be in d i c a t i v e of ir.tactness of the i n d i v i d u a l ' s s e l f m o n i t o r i n g system. S e l f - c o r r e c t i v e b e h a v i o r has not been, however, s y s t e m a t i c a l l y i n v e s t i g a t e d in d e m e n t i a p a t i e n t s .
T h e m a j o r i t y of s t u d i e s i n v e s t i g a t i n g intrusions r e p o r t that t h e s e e rrors are r a r e among h e a l t h y
e l d e r l y c o n trols (e.g., Fuld, 1983; S h i n d l e r et al. 1984) and, t h e r e f o r e h e l p f u l in d i s t i n g u i s h i n g normal s u b j e c t s from d e m e n t e d subjects. The o c c u r r e n c e of
intru s i o n s in individuals with c o g n i t i v e i m p a i r m e n t of i n s u f f i c i e n t s e v e r i t y to be d i a g n o s e d as h a v i n g
d e m e n t i a has not b e e n s y s t e m a t i c a l l y investigated.
" N o r m a l ” A g i n g
T h e m a j o r i t y of n e u r o p s y c h o l o g i c a l studies
a d d r e s s i n g a g e - r e l a t e d changes in c o g n i t i v e a b i l ities r e p o r t some level of i mpairment (e.g., Rimm, . ~;88) . T he a m o u n t of loss that occurs from i n d i v i d u a l to
i ndividual a p pears to be, however, h i g h l y v a r i a b l e (Drachman, 1986). Education, p r e s e n c e of c h r o n i c disease, a n d a d v a n c e d age are among the m o s t c o mmon f a c tors i n f l u e n c i n g level of c o g n i t i v e f u n c t i o n i n g in this popula t i o n . Specifically, d e c r e m e n t s in
n e u r o p s y c h o l o g i c a l p e r f o r m a n c e a ppear to be
p a r t i c u l a r l y e v i d e n t after the eight d ecade (Back & Greene, 1980; Benton, Eslinger, & Damasio, 1981; M i t r u s h i n a & Satz, 1991). T h e l i t e r a t u r e on "normal" aging c o n s i s t e n t l y indicates t h a t the m o s t e v i d e n t n e u r o p s y c h o l o g i c a l d e f i c i t s o b s e r v e d in this p o p u l a t i o n involve (1) d i m i n i s h e d a b i l i t y to encode a n d r e t r i e v e newly l e a rned information, p a r t i c u l a r l y n o n v e r b a l m a t e r i a l s (e.g., C h r i s t e n s e n et al., 1991; Poon, 1985), (2)
1987), and (3) d i f f i c u l t i e s in c o n c e p t f o r m a t i o n and m e n t a l flexib i l i t y (e.g., Reese, & Rodeheaver, 1985).
P o o n (1985) r e v i e w e d findings of small age-
r e l a t e d d e f icits in r e c o g n i t i o n and large a g e - r e l a t e d d e f i c i t s in r e c a l l s u g g e s t i n g that r e t r i e v a l r a t h e r t h a n s t o r a g e of i n f o r m a t i o n is i m p aired in the
elderly. Similarly, p r o c e d u r e s i n v o l v i n g c o m p a r i s o n s b e t w e e n free- and c u e d - r e c a l l tasks show i m p r o v e m e n t in p e r f o r m a n c e after p r e s e n t a t i o n of cues, w h i c h c o n t r a s t s w i t h AD p a t i e n t s i n a b ility to b e n e f i t from cues (Cushman et al., 1988). The v i e w t h a t r e t r i e v a l is impaired in the e l d erly r e c e i v e s f u rther s u pport f r o m s t udies r e p o r t i n g that the m e m o r y p e r f o r m a n c e of t h e s e i n d i v i d u a l s is e n h a n c e d by the p r o v i s i o n of e l a b o r a t i v e o r o r i e n t i n g i n s t r u c t i o n s (Smith, 1980) . T h e r e h a v e been, however, some c o n t r a d i c t o r y f i n dings
s h o w i n g d e f i c i e n t e n c o d i n g (i.e., r e c o g n i t i o n memory) in "normal" e l d e r l y (Flicker et al. 1986).
In c o n t r a s t to the findings of i m p a i r e d l e a rning a n d/or r e t r i e v a l of information, m i n i m a l or no age d i f f e r e n c e s in immediate m e m o r y ( e . g . , d i g i t span) or in r e m o t e m e m o r y (i.e., w e l l learned f a m iliar
information) w e r e r e p o r t e d in the m a j o r i t y of the s t u d i e s in t h e literature (Poon, 1985; Drachman, 1986). Similarly, g e n e r a l i n t e l l e c t u a l a b i l i t i e s
19 (i.e., m a n i p u l a t i o n of knowledge) and language
f u n c t i o n s a ppear to be r e l a t i v e l y i n s e n s i t i v e to the a g i n g p r o c e s s (Cummings & Benson, 1983; Flicker et a l . , 1986).
Tw o n e u r o p s y c h o l o g i c a l m o d e l s h a v e been proposed to e x p l a i n the p a t t e r n of c h a n g e s a s s o c i a t e d with
no r m a l a g i n g (Van Gorp, & Mahler, 1990). O n e m o d e l is b a s e d on the o b s e r v a t i o n s that there is a
d i s p r o p o r t i o n a t e d e c l i n e on the p e r f o r m a n c e of n o n v e r b a l r e l a t i v e to v e r b a l tasks in the elderly, s u g g e s t i n g a r i g h t h e m i s p h e r e i n v o l v e m e n t in the c o g n i t i v e d e t e r i o r a t i o n t h a t Occurs in this
p opulation. T h i s v i e w is s u p p o r t e d b y the "classic a g i n g p a t t e r n " d e s c r i b e d by A l b e r t & K a p l a n (198 0) who o b s e r v e d d e c r e a s e d P e r f o r m a n c e IQ and r e l a t i v e l y
s t a b l e V e r b a l IQ w i t h age. This m o d e l has been
criticized, however, since the n o n v e r b a l m e a s u r e s used in m o s t studies are also n ovel and t i m e - d e p e n d e n t
w h i c h does not p r o v i d e s p e cific e v i d e n c e for a r i g h t / l e f t d iscrimination.
The s econd m o d e l p r o p o s e s that t h e basal ganglia, w i t h c o n n e c t i o n s to frontal cortical structures, may b e p a r t i c u l a r l y a f f e c t e d by the aging process. These s t r u c t u r e s are i n v o l v e d in the speed of i n i t i a t i n g and e x e c u t i n g actions, a f u n c t i o n t h a t is a f f e c t e d in the
el d e r l y (Van Gorp & Mahler, 1990). Additionally, s e v e r a l studies have r e p o r t e d p o s i t i v e c o r r e l a t i o n s b e t w e e n age a n d m e a s u r e s indicative of f r ontal lobe d y s f u n c t i o n (Van Gorp, Mitrushina, Cummings, Satz, & Modessit, 1989; W h e l i h a n & Lesher, 1985). In a r e c e n t review, Craik (1991) a r g u e d that age d e c r e m e n t s are o b s e r v e d w h e n e v e r n o n - r o u t i n i z e d m e n t a l o p e r a t i o n s i n v o l v i n g initiation, o r g a n i z a t i o n and execution, i.e., o p e r a t i o n s r e q u i r i n g frontal lobe involvement, ar e performed. A l t h o u g h G o l d b e r g (198 6) a r g u e d that an y d i f f u s e b r a i n d amage d i s r u p t s frontal e x e c u t i v e f u n c t i o n s first, n e u r o b i o l o g i c a l data a p p e a r to s u g g e s t that f r o n t a l - s u b c o r t i c a l systems are m o s t v u l n e r a b l e to aging and are r e s p o n s i b l e for s e veral a g e - r e l a t e d deficits.
In sum, a brief r e v i e w of the n e u r o p s y c h o l o g y of a g i n g l i t e r a t u r e suggests that d i f f i c u l t i e s in the r e c a l l of n e w l y learned i n f o r m a t i o n is one of the m o s t p r o m i n e n t a g e - r e l a t e d c h a n g e s in this population.
F urthermore, c o g n i t i v e a b i l i t i e s involving the
p a r t i c i p a t i o n of the frontal lobes also a p p e a r to be a f f e c t e d by the a g i n g process.
*
A g e - R e l a t e d M e m o r y Defic i t s
T h e o b s e r v a t i o n that m e m o r y d e c l i n e is one of the e a r l i e s t m a r k e r s of AD a n d is also a s s o c i a t e d with " normal" a g i n g m a k e s the d i f f e r e n t i a t i o n b e t w e e n very m i l d A D and a g e - r e l a t e d m e m o r y d e f i c i t problematic. T h e r e l e v a n c e of a c c u r a t e l y c h a r a c t e r i z i n g individuals d i s p l a y i n g m e m o r y i m p a i r m e n t h a s b e e n e m p h a s i z e d by e p i d e m i o l o g i c a l r e ports e s t i m a t i n g t h a t w h i l e b e t w e e n 5 and 2 0 p e r c e n t of the p o p u l a t i o n over 65 years of a g e s uffer f r o m m i l d to s e v e r e d e m e n t i a (e.g.,
Morti m e r , Schuman, & French, 1981), m a n y of the r e m a i n i n g m e m b e r s of the g e r i a t r i c p o p u l a t i o n also d i s p l a y some d e g r e e of c o g n i t i v e d e t e r i o r a t i o n
(Cuimnings & Benson, 1983) . Furthermore, a recent
e p i d e m i o l o g i c a l s t u d y (Lane & Snowdown, 1989) r e p orted r e l a t i v e l y h i g h p r e v a l e n c e and incidence rates for a g e - a s s o c i a t e d m e m o r y i m p a i r m e n t (Prevalence: 34.93%
(SE 4.54); Incidence: 6.63% (SE 9.41) per annum) as c o m p a r e d to A D (Prevalence: 13.01% (SE 7.11.);
Incidence: 3.06% (SE 9.79) per annum).
K r a i (1978) w a s the first to d e s c r i b e benign s e n e s c e n t f o r g e t f u l n e s s (BSF) as a c i r c u m s c r i b e d m e m o r y d e f i c i t that is l a r g e l y i n d e p e n d e n t of
i m p a i r m e n t in other c o g n itive abilities. BSF has been l a r g e l y r e c o g n i z e d in the literature of clini c a l
aging, but it has b e e n c r i t i c i z e d as being p o o r l y o p e r a t i o n a l i z e d and i n s u f f i c i e n t l y v a l i d a t e d for
r e s e a r c h p u r p o s e s (Crook, Bartus, Ferris, W h itehouse, Cohen, & Gerson, 1986).
Recently, a N a t i o n a l I n s t itute of M e n t a l H e a l t h (NIMH) work g r o u p (Crook et al. 1986) p r o p o s e d
s p e c i f i c d i a g n o s t i c c r i t e r i a to d e s c r i b e t h e m e m o r y loss t h a t m a y occur in healthy, e l d e r l y i n d i v i d u a l s in t h e later d e c a d e s of life. The t e r m a g e - a s s o c i a t e d m e m o r y impair m e n t (A A M I ) has been s e l e c t e d to
c h a r a c t e r i z e individuals who c o m p l a i n of m e m o r y i m p a i r m e n t in tasks of d a i l y living and d i s p l a y e v i d e n c e of such i m p a i r m e n t on p s y c h o l o g i c a l p e r f o r m a n c e tests w i t h a d e q u a t e n o r m a t i v e data. Briefly, the criteria include (1) p e r s o n s o v e r 50 y ears of age, (2) c o m p l a i n t s of m e m o r y loss that are e v i d e n t in e v e r y d a y activities, (3) p e r f o r m a n c e o n a s t a n d a r d i z e d test of s e c o ndary m e m o r y that is at least o n e s t a n d a r d d e v i a t i o n b e l o w the m e a n (4) e v i d e n c e of p r e s e r v e d i n t e l l e c t u a l function, and (5) a b s e n c e of d e m e n t i a (i.e., a score of 24 or h i g h e r on the M i n i M e n t a l State E x a m ) . Some of the e x c l u s i o n c r i t e r i a a re (1) n e u r o l o g i c d i s o r d e r s that c o u l d p r o d u c e c o g n i t i v e d e t e r ioration, (2) h i s t o r y of h e a d injury,
(3) c u r r e n t d i a g n o s i s of p s y c h i a t r i c disorder, h i s t o r y of a l c o h o l i s m or d r u g dependence.
Y o u n g j o h n and c o l l e a g u e s (1991) r e p o r t e d p o s i t i v e r e s u l t s in d i s c r i m i n a t i n g p e r s o n s w i t h AAMI from AD p a t i e n t s b a s e d on t h e N I M H criteria, o b j e c t i v e
m e a s u r e s of m e m o r y function, as well as on self and f a m i l y r a t i n g s of e v e r y d a y m e m o r y function.
R e i s b e r g and c o l l e a g u e s (1986) r e p o r t e d a l o n gitudinal f o l l o w - u p s t u d y of p a t i e n t s w i t h d egree of m e m o r y
im p a i r m e n t r a n g i n g from v e r y m i l d to severe. The a u t h o r s c o m b i n e d a c u t t i n g score of 2 3 or less on the M i n i - M e n t a l S tate E x a m (MMSE; Eolstein, Folstein, & McHugh, 1975) w i t h a c u t t i n g score of 4 or less on the G l o b a l D e t e r i o r a t i o n Scale (GDS; Reisberg, Ferris, deLeon, & Crook, 1982) in order to identify
i n d i v i d u a l s w i t h AD. The r e s u l t s s u g g ested that
p e r s o n s d i s p l a y i n g v e r y m i l d or m i l d c o g n i t i v e d e c l i n e (i.e., above c u t o f f scores and m e e t i n g the c r i t e r i a for A A M I ) t e n d e d to r e m a i n s table over time. On t h e other hand, i n d i v i d u a l s s h o w i n g at least m o d e r a t e c o g n i t i v e d e c l i n e (i.e., at or b elow c u t o f f scores) h a d p o o r prognosis.
B l a c k f o r d and La Rue (1989) r e v i s e d the c r i t e r i a f or d i a g n o s i n g AAMI and p r o p o s e d g u i d e l i n e s for
w i t h m e m o r y deficit. Briefly, the a u t h o r s a r g u e d that since there is a lack of n o r m a t i v e data for v e r y old samples, indivi d u a l s 80 years of a g e or older s h o u l d not be identified as h a ving AAMI. Furthermore, they s u g g e s t e d the d i f f e r e n t i a t i o n of t h r e e s u b t y p e s of o b j e c t i v e m e m o r y impairment. The t e r m A A M I is r e t a i n e d as p r o p o s e d by the N I M H group. Two
a d d i t i o n a l c a t e g o r i e s are u s e d to d e s c r i b e (a) age- c o n s i s t e n t m e m o r y impai r m e n t (ACMI) w h i c h includes p e r s o n s w i t h i n the AAMI g r o u p w h o s e m e m o r y is in
a c c o r d w i t h n o r m a t i v e data (i.e., p e r f o r m a n c e w i t h i n + or - 1 s t a n d a r d d e v i a t i o n of the m e a n on 75% or more of the tests), and (b) l a t e -life f o r g e t f u l n e s s (ILF) w h i c h i n c ludes individuals w h o c o n s i s t e n t l y s c o r e b e l o w a v e r a g e on m e m o r y m e a s u r e s (i.e., p e r f o r m a n c e b e t w e e n 1 and 2 standard d e v i a t i o n s b e l o w the m e a n on 50% or m o r e of the t e s t s ) .
A l t h o u g h the litera t u r e s u g g e s t s t h a t some p r o g r e s s has been a c h i e v e d in d e l i n e a t i n g s p e c i f i c g u i d e l i n e s for the e v a l u a t i o n of c o g n i t i v e d e c l i n e in
"normal" aging, t h e s e g u i d e l i n e s are not w i d e l y used, an d t h e r e is some c o n t r o v e r s y r e g a r d i n g t h e d i a g n o s t i c t e r m i n o l o g y a n d criteria. F uture r e s e a r c h is,
a n d r e l e v a n c e of b o t h the NIMH c r i t e r i a and Blaickford a n d La Rue's (1989) revisions.
T h e import a n c e of d i a g n o s i n g m e m o r y i m p a i r m e n t in "normal'' a g i n g has been further emphas i z e d in recent st u d i e s that a t t e m p t e d to d i f f e r e n t i a t e g r o u p s of e l d e r l y a c c o r d i n g to level of c o g n i t i v e i m p a i r m e n t an d / o r its p r o g r e s s i o n o v e r a p e r i o d of time.
S t o r a n d t and Hill (1989) c o m p a r e d i n d i v i d u a l s w i t h v e r y m i l d or q u e s t i o n a b l e dementia, m i l d dementi);, and h e a l t h y c o n trols on v a r i o u s p s y c h o m e t r i c tests. T h e L o g i c a l M e m o r y s u b t e s t of the W e c h s l e r M e m o r y Scale m a d e t h e largest c o n t r i b u t i o n t o the d i s c r i m i n a t i o n among groups. T h e r e was, however, s i g n i f i c a n t overlap b e t w e e n p e r f o r m a n c e s of the q u e s t i o n a b l e g r o u p w i t h both t h e h e a l t h y a n d m i l d l y d e m e n t e d groups.
A n o t h e r s tudy by M o r r i s a n d c o l l e a g u e s (1991) also a t t e m p t e d to e x a m i n e the issue of cogni t i v e p e r f o r m a n c e o v e r l a p b e t w e e n h e a l t h y e l d e r l y and p a t i e n t s w i t h q u e s t i o n a b l e dementia. S i m i l a r to
p r e v i o u s studies, the q u e s t i o n a b l e g r o u p ' s p e r f o r m a n c e on the L o g i c a l Memory, P a i r e d A s s o c i a t e L e a r n i n g
(i.e., h a r d associates) s u b t e s t s of the W e c h s l e r M e m o r y S c a l e - R e v i s e d (Wechsler, 1987), and on the I n f o r m a t i o n s u b t e s t of 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 - R e v i s e d (Wechsler, 1981) w a s s i g n i f i c a n t l y w o r s e than t h a t of the control group.
O t h e y studies have e x a m i n e d the l o n g i t u d i n a l
f o l l o w - u p of c o g n i t i v e l y i m p a i r e d individuals. R u b i n and c o l l e a g u e s (1989) s t u died 16 p a t i e n t s w i t h
q u e s t i o n a b l e d e m e n t i a of t h e A l z h e i m e r type, 44
s u b j e c t s w i t h m i l d A D and 58 controls. E leven of the p a t i e n t s w i t h q u e s t i o n a b l e AD (i.e., m i l d c o g n i t i v e i m p a i r m e n t insufficient in d e g r e e to d i a g n o s e
dementia) either p r o g r e s s e d to a d e m e n t i a stage over an 8 4 - m o n t h f o l l o w - u p p e r i o d or had A D v e r i f i e d at autopsy. Interestingly, all s u b j e c t s who d i s p l a y e d e v i d e n c e of m o d e r a t e m e m o r y loss at e n t r y p r o g r e s s e d in g lobal d e m entia severity.
T u o k k o and c olleagues (1991) r e p o r t e d that a m o n g 4 5 s u b jects w h o did not m e e t the c r i t e r i a for d e m e n t i a at initial assessment, 18 w e r e d i a g n o s e d as h a v i n g p o s s i b l e or p r o b a b l e AD u p o n r e a s s e s s m e n t (i.e., 12-18 m o n t h s l a t e r ) , w h i l e 27 s u b j e c t s r e m a i n e d unchanged. T h e a u t h o r s o b s e r v e d that the. d i f f e r e n c e s b e t w e e n the " c h a n g e ” and "no change" g r o u p s were m o s t e v i d e n t on a m e a s u r e of r e t r i e v a l of i n f o r m a t i o n (i.e., free
r e c a l l ) . Finally, K a t z m a n (1986) c o m m e n t e d on a study in w h i c h n ormal 8 0 - y e a r - o l d i n d i v i d u a l s who d i s p l a y e d evide n c e of m e m o r y d e f i c i t o n m e n t a l s tatus
te s t s w e r e at a s i g n i f i c a n t l y increased r i s k for d e v e l o p i n g (or b e i n g in an early s t a g e of) d e m entia t h a n t h e i r c o h o r t s who m a d e no e rrors on these tests. T h e a uthor e m p h a s i z e d that since t h e r e is no clear e v i d e n c e t.^at all such p e r s o n s w i l l d e v e l o p dementia, r e - e v a l u a t i o n at r e g u l a r intervals is recommended.
T h e f o r e g o i n g studies suggest, therefore, that t h e d i s t i n c t i o n b e t w e e n indivi d u a l s who d i splay m i l d c o g n i t i v e i m p a i r m e n t and persons in the early stages of a d e m e n t i n g p r o c e s s is p a r t i c u l a r l y e v i d e n t on
m e m o r y - r e l a t e d tasks, even t h o u g h c o n s i d e r a b l e o v erlap b e t w e e n g r o u p s exists. Some of t h e p e r sons i dentified as h a v i n g m e m o r y impair m e n t either may be at r i s k for d e v e l o p i n g AD or m a y in fact be in a v e r y mild stage of the disease. C o n t i n u e d longi t u d i n a l e v a l u a t i o n s of t h e s e cases w o u l d be n e c e s s a r y in order to address the n a t u r a l h i s t o r y of m e m o r y changes in the elderly.
Finally, a l t h o u g h some specific g u i d e l i n e s for the c l a s s i f i c a t i o n of m e m o r y impaired i n dividuals have b e e n r e c e n t l y p r o p o s e d ( e . g . , A A M I ) , further r e s e a r c h is n e c e s s a r y t o d e t e r m i n e the adequacy of such
criteria.
Overall, t h e liter a t u r e indicates t h a t a l t h o u g h i m p a i r m e n t in r e c a l l i n g n e w l y learned i n f o r m a t i o n is p r o m i n e n t in t h e elderly, t h e r e a p p e a r t o be a
s i g n i f i c a n t number of i ndividuals w h o d i s p l a y a m o r e s evere a nd/or c i r c u m s c r i b e d d e f i c i t in m e m o r y - r e l a t e d activities. The c h a r a c t e r i z a t i o n of t h e s e p e r s o n s as a separate g r o u p (i.e., AAMI) is at p r e s e n t
p r o b l e m a t i c since t h e d e g r e e a n d p a t t e r n of impair m e n t is h i g h l y variable, and it m a y a c t ually r e p r e s e n t the e a r l y stages of a p r o g r e s s i v e d e g e n e r a t i v e disorder.
A w a r e n e s s / U n a w a r e n e s s of M e m o r y F u n c t i o n i n g
M o s t studies d o c u m e n t i n g t h e c h a r a c t e r i s t i c m e m o r y d e f i c i t s in d e m e n t i a p a t i e n t s h a v e not a d d r e s s e d t h e issue of t h e d e g r e e of a w a r e n e s s of m e m o r y impairment d i s p l a y e d by these patients. V e r y f e w r e s e a r c h e r s a t t e m p t e d to i n v e s t i g a t e the a w a r e n e s s p h e n o m e n a systematically. M o s t of t h e r e s e a r c h in the area is b a s e d on c l i n i c a l descriptions.
Overall, the litera t u r e on a w a r e n e s s of d e f i c i t in d e m entia s u g g e s t s that the u n a w a r e n e s s p h e n o m e n a do occur in this syndrome. Lack of a w a r e n e s s is m o s t f r e q u e n t l y r e p o r t e d in d e m e n t i a s such as AD and Pick's d i s e a s e (Benson, 1983; G u s t a f s o n & Nilsson, 1982;
N e a r y et al. 1986).
R e i s b e r g and c o l l e a g u e s (1985) e x a m i n e d the r e l a t i o n s h i p b e t w e e n a n o s o g n o s i a and s e v e r i t y of d e m e n t i a u s i n g c l i nical interv i e w s of p a t i e n t s and
relatives. S u b jects included e l d e r l y n ormal controls, s u b j e c t s with c o g n i t i v e d e f i c i t s (i.e., m a i n l y m e m o r y impairment) a n d A l z h e i m e r patients of v a r y i n g d e m entia s e v e r i t y (mild to s e v e r e ) . The results r e v e a l e d a st r o n g r e l a t i o n s h i p b e t w e e n self- a w a r e n e s s of d e f i c i t s and d e g r e e of c o g n i t i v e d e t e rioration. T h e subjects w i t h c o g n i t i v e d e f icits a n d m i l d AD p a t i e n t s r ated t h e i r m e m o r y p r o b l e m s as s o m e w h a t w o r s e t h a n did the c o n t r o l s s h o w i n g a w a r e n e s s of their skills. In
contrast, m o d e r a t e l y d e m e n t e d p a t i e n t s a d m i t t e d some c o g n i t i v e d e f i c i t s but t e n d e d to m i n i m i z e the extent of t h e i r impairment w h i l e m o r e s e v e r e l y d e m e n t e d p a t i e n t s t e n d e d to deny p r o b l e m s entirely.
Additi o n a l l y , the d i s c r e p a n c y b e t w e e n relatives' and s e l f - d e s c r i p t i o n s b ecame s i g n i f i c a n t l y larger (i.e., v i t h r e l a t i v e s r e p o r t i n g m o r e impairment) as demen t i a s e v e r i t y increased.
Conversely, several s t udies (Frederiks, 1985; J o y n t & Shoulson, 1985: M c G l y n n & Kaszniak, 1991a) r e p o r t e d loss of insight in early stages of AD.
M a h e n d r a (1984) observed early loss of insight in both A D and P i ck's d i s e a s e and associ a t e d this f i n d i n g with t h e frontal lobe i n v o l v e m e n t t y p i c a l l y r e p o r t e d in t h e s e syndromes. Furthermore, a weak r e l a t i o n s h i p b e t w e e n s e v e r i t y of d e m e n t i a and u n a w a r e n e s s of m e m o r y
