The Relationship between Depression and Intelligence in Adolescents: A Systematic Review Sofie Burger 10651101 University of Amsterdam 24-01-2016
Assessor: Mw. Dr. A.L. van den Akker Word count: 5388
Table of Contents
Abstract ... 3
The relation between depression and intelligence in adolescents ... 4
Method ... 7 Results ... 8 General intelligence ... 8 Performal intelligence ... 12 Verbal intelligence ... 13 Discussion ... 13 References ... 19
Abstract
In this systematic review 21 studies were included to study the relation between depression and intelligence in adolescents. Peer reviewed studies were included if they focused on general, performal or verbal intelligence and depressive symptoms or depressive disorder in adolescents without another diagnosis. A negative relation was found between all types of intelligence and depressive symptoms, but not depressive disorder, and only for adolescents of average intelligence. Intellectually disabled adolescents showed less depressive symptoms and highly gifted adolescents showed more depressive symptoms than adolescents of average intelligence. The relation between depression and intelligence appeared to be mutual. Future studies should focus on the direction of the relation, use Sternberg’s division of intelligence and be aware of the difference between depressive symptoms and depressive disorder.
The Relation between Depression and Intelligence in Adolescents
Adolescence is a period characterised by an increase of depression, varying from mild depressive symptoms (Hamlat et al., 2014) up to severe major depression disorder (MDD) (Verboom, Sijtsema, Verhulst, Penninx, & Ormel, 2014), which is one of the most prevalent disorders in adolescents (Wagner, Müller, Helmreich, Huss, & Tadić, 2014). It is estimated that 2.8% of the children suffer from a depressive disorder and 5.7% of the adolescents (Costello, Erkanli, & Angold, 2006). Depression can be pervasive; of all adolescents who have experienced a period of MDD, 40% experiences a second episode of MDD within 5 years. Furthermore, it influences the adolescent on multiple domains, since it often goes hand in hand with problems as poor academic performance, low self-esteem and negative body image (Mueller, 2009).
Depression is characterized by a pervasive sadness or loss of interest in everyday activities (Muelller, 2009). Depressive symptoms are for example being too tired to do things, feeling like your life has been a failure, having trouble keeping your mind on what you are doing, being bothered by things that normally do not bother you, decreased appetite, feelings of worthlessness or guild or feeling depressed (Beaujean, Parker, & Qiu, 2013). When a person experiences pervasive sadness or loss of interest for at least two weeks in combination with at least four other depressive symptoms that cause impairment in everyday functioning, he or she is diagnosed with MDD, according to the latest version of the Diagnostic and
Statistical Manual of Mental Disorders (American Psychiatric Association, 2013).
Since depression is pervasive and has such an impact on everyday functioning, researchers have tried to find factors that place adolescents at risk of developing depression, so the development of depression might be prevented. Researchers already found that in adolescence girls suffer more often from depression than boys and that adolescents are more at risk than children (Guyer, Choate, Grimm, Pine, & Keenan, 2011; Wagner et al., 2014).
Furthermore, experiencing multiple adverse events, such as being bullied or death of a relative (Mueller, 2009) and living with a depressed parent (Horowitz & Garber, 2003) are factors placing adolescents at risk. However, not all people who experience negative life events become depressed. Therefore, researchers have hypothesised that the way people react to or interpret a negative event might be a stronger predictor of depression than the event itself. For example, adolescents who react on a negative life event with ruminating are found to be more vulnerable of developing a depressive disorder than adolescents who ruminate less (Hamlat et al., 2014), and so are adolescents who retrieve more general memories of the event, instead of specific memories (Hipwell, Sapotichne, Klostermann, Battista, & Keenan, 2011). Since these are cognitive factors, also intelligence might relate to depression. Several studies have indeed found this relation (Wagner et al., 2014), but it is not clear whether intelligence is a risk factor for, or a consequence of depression.
Intelligence is the ability to “reason, plan, solve problems, think abstractly,
comprehend complex ideas, learn quickly and learn from experience” (Nisbett et al., 2012, p. 131) and is often divided into verbal intelligence and performal intelligence (Wagner et al., 2014). This division is also made in the intelligence tests of Wechsler, among which the often used Wechsler Intelligence Scale for Children (WISC) or Wechsler Adults Intelligence Scale (WAIS). Verbal intelligence includes the mastery of language, reasoning and general
knowledge (Wechsler 1974, as cited in Tak, Bosch, Begeer, & Albrecht, 2014), while performal intelligence consists of recognizing patterns, spatial awareness, visualisation and processing speed.
The relation between depression and intelligence is explained in different ways. Both the hypothesis of cognitive reserve and the competency-based model assume that low
intelligence is a risk factor for the development of depression (Koenen et al., 2009; Verboom et al., 2014). The hypothesis of cognitive reserve states that certain differences in brain
structure and function buffer the effect of neuropathology (Koenen et al., 2009). Higher cognitive reserve may for example make people better able to deal with stressful events, which makes them less vulnerable to mental disorders. Another explanation comes from the competency-based model (Verboom et al., 2014). This model assumes that poor performance in several domains leads to more negative feedback from others and subsequently leads to negative self-perception, which is a risk factor for the development of depression (Verboom et al., 2014). Since low intelligence can lead to poor performance, it could be a risk factor
according to this model. In contrast to what these two explanations expect, the direction of the relation could also be the other way around, assuming that depression leads to poor
performance on intelligence tests (Wagner et al., 2014). People who are depressed often report problems with attention, concentration and memory or decreased motivation to perform well (Favre et al., 2008; Wagner et al., 2014), what could cause them to make the intelligence test less well. Accordingly, the explanations of the relation between intelligence and
depression differ in whether they consider the level of intelligence as a risk factor for depression or as a consequence of depression.
To bring more clarity in this research field, studies to the relation between depression and intelligence will be reviewed in this study. Adolescence is a period in which the
prevalence of depression increases (Verboom et al., 2014), but most previous research has focused on adults (Glaser et al., 2011). Therefore, this study will focus on adolescents. Next to bringing clarity in this research field, this study can also provide practically important information on a potential risk factor for depression. Since depression has a severe negative impact on the life of adolescents (Wagner et al., 2014) and causes a lot of costs for society (Weeks et al., 2014), it is important to discover how to prevent its development. Studying risk factors can help determine which adolescents are at risk, which can lead to better preventive programmes. Therefore this systematic review will focus on the relation between depression
and intelligence in adolescents. Both the relations between general, verbal and performal intelligence and depression will be studied.
Following the hypothesis of cognitive reserve and the competency-based model, it is expected that a negative relationship will be found between depression and general
intelligence, as well as verbal and performal intelligence. This is expected, since low general, verbal and performal intelligence all might lead to poor performance, which places
adolescents at risk for developing depression. However, there could also be a difference between verbal and performal intelligence. Since ruminating is a verbal process (Koster, De Lissnyder, Derakshan, & De Raedt, 2011), higher verbal intelligence might co-occur with more ruminating, which is a symptom of depression. Therefore a positive relation between depression and verbal intelligence could be expected. However, a person with high performal intelligence is good at recognizing patterns and seeing the bigger picture, which might make the person better able to see that the negative thoughts and feelings are inordinate and not realistic. This implicates that a negative relation between depression and performal intelligence could be expected.
Method
Studies were searched in the electronic databases Web of Science, PsycInfo, Eric and Pubmed. These databases were searched with different terms related to intelligence (verbal intelligence OR performal intelligence OR general intelligence OR IQ OR cognitive ability) combined with terms related to depression (depression OR depressive symptoms OR
depressive disorder) and terms to define the participants (adolescen* OR youth OR teenage*). Furthermore, the studies included in the meta-analysis of Wagner et al. (2014) were taken into account. Next, the abstracts of the studies were read, and when necessary the full text, to determine whether the studies met the following eligibility criteria. First, studies had to include general, verbal or performal intelligence and depressive disorder or depressive
symptoms and had to report the relation between both. Second, the measurement of depression had to be with adolescents between ages 11 and 21. Third, studies were not included if they compared intelligence of depressed adolescents to intelligence of adolescents with another disorder or disease, instead of healthy controls. Fourth, the studies had to be peer-reviewed. Finally, the studies had to be in English or in Dutch.
The included studies were coded on type of intelligence (general, verbal or performal), intelligence measurement instrument, type of depression (depressive symptoms or depressive disorder), depression measurement instrument, age of participants, percentage of girls
included and study design (Table 1).
Results
The searching of the databases and screening of abstracts resulted in 35 studies
selected for full review. After screening for the eligibility criteria, 22 studies were included in this systematic review.
General Intelligence
Thirteen studies focused on the relation between general intelligence, mostly measured by IQ, and depression. These studies overall showed that adolescents in the normal
intelligence range, who reported more depressive symptoms, generally had lower general intelligence (Alvarez, Sotres, Leon, Estrella, & Sosa, 2008; Horowitz & Garber, 2003; McClure, Rogeness, & Thompson, 1997). In contrast, adolescents with a depressive disorder did not seem to differ from healthy adolescents in their level of general intelligence (Frost, Moffitt, & McGee, 1989; Günther, Konrad, De Brito, Herpertz-Dahlmann, & Vloet, 2011; Kyte, Goodyer, & Sahakian, 2005; Maalouf et al., 2011; Park, Goodyer, & Teasdale, 2004). Besides whether studies focused on depressive symptoms or depressive disorder, several other factors have been taken into account. First, the relation between depression and general
intelligence for intellectually disabled or gifted adolescents, second the influence of age and gender of the participants on the relation and third the direction of the relation.
Five of the included studies found a negative relation between depressive symptoms and general intelligence. However, the studies of Benavidez and Matson (1993), Glaser et al. (2011) and Bénony, Van Der Elst, Chahraoui, Bénony and Marnier (2007) also found a positive relation, assuming that higher general intelligence co-occurs with more depression, for specific participants. Benavidez and Matson (1993) focused on students with an
intellectual disability, with an IQ score below 70. The intellectual disabled students reported less depressive symptoms than intellectual average students. Bénony et al. (2007) on the other hand, focused on gifted adolescents, with an IQ score of 130 or more. Gifted adolescents showed more depressive symptoms than non-gifted adolescents. This implied that the relation between general intelligence and depression might not be linear. If the relation would be negative and linear, intellectual disabled student would report the most depressive symptoms and gifted adolescent would report the least, but studies showed the opposite. Therefore, the in studies found negative relation between depression and general intelligence only seemed to apply to adolescents in the normal intelligence range.
Next to the studies that looked at particular high or low intelligence, also the study of Glaser et al. (2011), that focused on age, reported results inconsistent with the overall found negative relation. Glaser et al. (2011) found a difference in the relation between general intelligence and depressive symptoms at different ages. Adolescents of age 11 with high general intelligence reported less depressive symptoms than adolescents with lower general intelligence, while adolescents of age 13 and 14 with high general intelligence reported more symptoms than adolescents with lower general intelligence. The relation was negative at age 11 but positive at ages 13 and 14. This finding is not supported by the other included studies, since multiple studies found a negative relation at age 14 (Table 1).
According to most studies, the relation between depressive symptoms and general intelligence was the same for adolescents of different ages. However, in contrast to age, the relation between depression and general intelligence seemed to be dependent of the severity of depression. The included studies differed in how they defined depression. Some studies compared adolescents who met the DSM criteria for depressive disorder and healthy adolescents on their IQ-scores, while other studies measured the amount of depressive symptoms that participants experienced and related this to the intelligence scores. Of the studies that focused on depressive symptoms, seven studies (87.5%) found a relation between depressive symptoms and intelligence. This was different in the studies that focused on depressive disorder. Only one of these studies (17%) found a difference in the general intelligence of depressed adolescents and healthy adolescents. This seemed to imply that the amount of depressive symptoms is related to general intelligence, but depressive disorder is not. Therefore the relation between general intelligence and depression appeared to be dependent of the severity of the depression.
The study that did found a difference in the general intelligence of adolescents with a depressive disorder, was the study of Horowitz and Garber (2003). They came to the
conclusion that adolescents of healthy mothers had higher chance of having a depressive disorder themselves when they have a lower general intelligence. This finding supported the overall found negative relation between general depression and depressive symptoms. However, for adolescents of mothers with a depressive disorder, higher general intelligence was related to a higher chance of having a depressive disorder themselves. Horowith and Garber (2013) assumed that this could be explained by that more intelligent adolescents are more aware of the depression of their mothers than less intelligent adolescents, are more called upon to help and are more aware of the risk of developing depression themselves. This
could make adolescents feel more helpless and lead to more stressors, which places them at risk of developing depression.
One of the studies (Johnson, McGue, & Iacono, 2006) looked at gender as a
moderating variable and concluded that there was only a negative relation between general intelligence and depressive symptoms for girls and no relation for boys. The finding of Johnson et al. (2006) is contradicted by the other studies. Koolhof, Loeber, Wei, Pardini, & D'escury (2007) included only boys and still found a relation. However, Glaser et al. (2011) reported that boys showed less depressive symptoms than girls and found that the relation between general intelligence and depressive symptoms was smaller for boys than for girls.
Finally, two studies were longitudinal and focused on whether level of general intelligence of 8-year-old children predicted depression in adolescence and whether level of general intelligence could be considered a risk factor for depression instead of a consequence of depression. Glaser et al. (2011) and Kounali et al. (2014) came to different conclusions. Glaser et al. concluded that it was general intelligence that predicted the amount of depressive symptoms and not the other way around. Kounali et al. came to the conclusion that neither high, nor low general intelligence predicted whether adolescents experienced depression. The difference in their conclusions might be explained by the definition of depression or the age of their participants. Both measured intelligence at age 8, but Kounali et al. (2014) measured depression at age 18, while Glaser et al. (2011) measured depression at ages 11, 13, 14 and 17. On the other hand, Glaser et al. (2011) focused on amount of depressive symptoms, while Kounali et al. (2014) focused on whether the participants were depressed, which they defined as having a depression symptom score over 10 (range: 0-21). This might be comparable to depressive disorder, of which multiple studies found that it did not relate to general
Performal intelligence
It is not only studied whether general intelligence and depression relate, but also to what extent a relation between performal intelligence and depression exists. Five studies included scores of performal intelligence in their research, of which two found a significant negative relation between depression and performal intelligence (Alvarez et al., 2008; McClure et al., 1997) and three did not (Frost et al., 1989; Rohde, Noell, & Ochs, 1994; Wilkinson & Goodyer., 2006). The two studies that found a relation both had a small sample, but their results were strongly significant with p<.01. Whether or not a study found a relation between depression and performal intelligence did not seem to be related to age or gender of the included participants.
Adolescents with higher performal intelligence reported less depressive symptoms in the studies of McClure et al. (1997) and Alvarez et al. (2008), which is comparable to the relation found for general intelligence. However, this relation was not found by Rohde et al. (1994). A possible explanation for this might be that Rohde et al. (1994) focused on a specific group of adolescents; homeless adolescents. These adolescents might differ from
non-homeless adolescents in multiple things, for example in the amount of stressful events they experience. These differences between the adolescents might explain the different findings of the studies. Adolescents who had a depressive disorder, did not differ in their level of
performal intelligence from healthy adolescents (Frost et al., 1998; Wilkinson & Goodyer, 2006). These findings are comparable to the findings on general intelligence and depressive disorder. This might indicate that the relation between depression and performal intelligence, like the relation between depression and general intelligence, is dependent on the severity of depression.
Verbal intelligence
Finally, also the relation between depression and verbal intelligence is studied. Nine studies included verbal intelligence and depression, of which eight found a negative relation between the two (Alvarez et al., 2008; Beaujean et al., 2013; Guyer et al., 2011; Hipwell et al., 2011; Klimkeit, Tonge, Bradshaw, Melvin, & Gould, 2011; McClure et al., 1997; Mueller, 2009; Rohde et al., 1994). These studies concluded that adolescents with high verbal
intelligence reported less depressive symptoms. However, adolescents with a depressive disorder did not differ in verbal intelligence from healthy adolescents (Frost et al., 1989).This finding was comparable to the findings on general or performal intelligence and depressive disorder. However, Frost et al. (1989) included only a small number of depressed participants, which might explain why no significant difference could be found. The absence or presence of a relation did not seem to be related to the age or gender of the participants.
Inconsistent with the overall found negative relation between depressive symptoms and verbal intelligence, but consistent with the finding on general intelligence, was the result that intellectually disabled adolescents, with verbal IQ below 79, reported less depressive symptoms than adolescents with higher verbal intelligence (Manikam, Matson, Coe, & Hillman, 1995). Verbally gifted adolescents, on the other hand, reported fewer depressive symptoms than non-gifted adolescents (Mueller, 2009).
Concerning the direction of the relation between depression and verbal intelligence, only the study of Beaujean et al. (2013) focused on this aspect. This longitudinal study found that depression preceded lower verbal intelligence, but lower verbal intelligence did not predict depression.
Discussion
Summarizing the results, several conclusions can be made on the relation between depression and general, performal and verbal intelligence in adolescents. General intelligence
appeared to be negatively related to depressive symptoms, but not to depressive disorder. Contrastingly, for adolescents with very high or very low general intelligence, this relation appeared to be positive. The relation seemed to be independent of age or gender. Concerning the direction of the relation, general intelligence seemed to predict depression for adolescents up till 17 years, but not for adolescents of 18 years. Performal intelligence turned out to be negatively related to depressive symptoms, but not depressive disorder, independently of age or gender. A similar negative relation was found for verbal intelligence. However, only one study focused on verbal intelligence and depressive disorder, so no strong conclusion can be made on the influence of severity of depression on this relation. Contrary to the results on general intelligence, adolescents with extremely high verbal intelligence showed less
depressive symptoms than intellectually average adolescents. Also the direction of the relation seemed different for verbal intelligence, since depression seemed to precede lower verbal intelligence, but lower verbal intelligence did not predict depression. However, the direction was only taken into account in one study. Taken these conclusions on general, performal and verbal intelligence together, this systematic review indicates that there is a negative relation between intelligence and depressive symptoms, but not depressive disorder, and only for subclinical levels of depression and adolescents of average intelligence. These findings partly support the formulated hypothesis that depression and intelligence are negatively related.
This negative relation between depression and intelligence was only found for depressive symptoms and not for depressive disorder. A possible explanation for this difference might be that depressive disorder is not just an extreme amount of depressive symptoms. Depressive symptoms are experienced by everyone, only the extent to which they occur differ. A depressive disorder is not just characterized by a large number of depressive symptoms, but might be a construct that differs in development from depressive symptoms. The view of depressive disorder as a discrete category, instead of a dimension, is supported
by neurological research. Individuals with MDD are found to have certain differences in brain structure compared to healthy individuals (Mwangi, Ebmeier, Matthews, & Steele, 2012).
Besides the definition of depression, also the level of intelligence seemed to have influence on the relation between depression and intelligence. The finding that adolescents with extremely high general intelligence experienced more depressive symptoms underscores findings of previous studies. These studies stated that gifted students are at increased risk of developing depression due to their perfectionism (O’Connor, Rasmussen, & Hawton, 2010) and social isolation (Mueller, 2009), that can develop when adolescents feel they do not fit in with their peers due to their increased cognitive abilities. However, adolescents scoring extremely high on verbal intelligence showed fewer depressive symptoms than adolescents scoring average on verbal intelligence. This difference in findings might indicate that the relation between depression and intelligence is different for verbally gifted or generally gifted adolescents. It could on the other hand also be explained by the different tests that were used to measure intelligence and by their different definitions of gifted. Bénony et al. (2007), studying general intelligence, defined adolescents as gifted when they had an IQ over 130, which is two standard deviations above the mean, while Mueller (2009) defined gifted students as having an AHPTV score over 115, which is one standard deviation above the mean. This finding resembles the hypothesis that only extreme giftedness places adolescents at risk of developing psychological disorders (Mueller, 2009). Besides for the gifted
adolescents, the relation between depression and intelligence appeared also to be different for adolescents with intellectual disability, who reported less depressive symptoms than
intellectually average adolescents. This might be explained by intellectually disabled adolescents being less aware of negative events or negative thoughts. Another possible explanation is that depression is difficult to recognize and diagnose in intellectually disabled adolescents (Scott & Havercamp, 2015).
Concerning the direction of the relation between depression and intelligence, different results were found. Depression seemed to precede low verbal intelligence, which was
expected by the assumption that depression leads to poor performance on intelligence tests. On the contrary, low general intelligence seemed to predict depression, which was expected by the competency-based model and the hypothesis of cognitive reserve. The two contrasting findings do not exclude each other; low intelligence can precede depression while at the same time depression can lead to poor performance on tests.
Concerning verbal and performal intelligence, it had been hypothesized that they might relate differently to depression. Since higher verbal intelligence might go hand in hand with more ruminating, it was expected that adolescents with higher verbal intelligence would report more depression. Adolescents with higher performal intelligence were on the other hand expected to report less depression, since they might have more insight in the extent to which their negative thoughts and feelings are inordinate and unrealistic. The hypothesis that the relation between depression and intelligence might be different for verbal and performal intelligence, with verbal intelligence being positively related and performal intelligence being negatively related, was not supported by the included studies. Both performal and verbal intelligence appeared to be negatively related to depressive symptoms for non-gifted
adolescents. Possibly higher verbal intelligence does not co-occur with more ruminating, but more research should be conducted on this topic. Furthermore, following the competency-based model, low verbal and low performal intelligence can both lead to poor performance and therefore relate to depressive symptoms. Another explanation could be that verbal and performal intelligence are quite similar constructs. The division of general intelligence into verbal and performal intelligence is often made in practice (Wagner et al., 2014), but intelligence can also be defined and divided in other ways that might be more useful in studying the relation between depression and intelligence. The definition of intelligence by
Sternberg as “the ability to achieve success in life in terms of one's personal standards, within one's sociocultural context” (2006, p. 323) seems more suitable to study the competency-based model, since it focuses on intelligence as success achievement. Sternberg’s (2006) triarchic theory of intelligence assumes intelligence contains three aspects; analytic intelligence (comparable to general intelligence), practical intelligence and creativity. Practical intelligence and creativity are more external focused aspects of intelligence. Practical intelligence is the application of general intelligence in the real world. This is done with the help of tacit knowledge, which is “knowledge of what one needs to know to succeed in a given environment that is not explicitly taught and that usually is not verbalized”
(Sternberg & Kaufman, 1998, p. 494). It is knowledge of how to do something, instead of knowledge of facts. Creativity is the application of general intelligence in novel situations and the creating of new solutions to problems. Since Sternberg’s external focused aspects and general intelligence are different types of intelligence, they might relate differently to depression. The external focused aspects fit the competency-based model, while the internal focused aspect seems to fit the cognitive reserve hypothesis better.
Since Sternberg’s definition and division of intelligence might be more useful for studying the relation between depression and intelligence, it could be recommended that future research does not focus on the division of intelligence into general, performal and verbal intelligence, but on the division of Sternberg instead. Furthermore, it is important that future research focuses on the direction of the relation, since in this study, only three studies could be included that focused on it and they came to different results. Besides, researchers should be aware of the influence of severity of depression when they conduct research to the relation between depression and intelligence.
Since a negative relation is found between intelligence and depressive symptoms, low intelligence could now be considered a risk factor for adolescents to experience depressive
symptoms. Knowing which adolescents are at risk can help to determine earlier if adolescents experience depressive symptoms. In this way, help can be offered earlier and therefore
suffering of the adolescents can be decreased. Since depression can be pervasive and have a severe negative impact on the functioning of the adolescent, offering help as early as possible is important. In this way, the suffering of the adolescent and the costs for society can both be decreased.
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Table 1
Summary of the Research Characteristics
Study Population description
N % Female Age (M) Intelligence Measure
Depression Measure
Results Study Design
Alvarez et al., 2008 Students diagnosed with MDD 31 58% 22.7 WAIS; FSIQ, VIQ, PIQ Depressive symptoms (BDI) FSIQ (BT: M=98.2, AT: M=111.4) VIQ (BT: M=101.9, AT: M=116.5) PIQ (BT: M=95.3, AT: M=109.5) (F(2, 28) = 44.892, p < 0.001) Cross-sectional Beaujean et al., 2013
Sample from the National Longitudinal Study of Adolescent Health 12322 49% Wave I: 16.0 Wave III: 22.4 AHPVT Depresssive symptoms (Combination of items related to depression)
r (AHPTV Wave I, Depression
Wave I) = -.20
r (Depression Wave I, AHPTV
Wave III) = -.17 Longitudinal Benavidez & Matson, 1993 Mentally retarded adolescents and normal IQ adolescents 50 (25;25) 40% 14.5 WISC-R; FSIQ Depressive symptoms (CDI, BID, RCDS)
Adolescents with IQ<70 had lower scores on the BID
(F(l, 48) = 13.21, p <.008) Cross-sectional Bénony et al., 2007 Gifted (IQ≥130) and non-gifted (IQ<130) adolescents 48 (Gifted;23, Non-gifted; 25) 50% (Gifted; 43.5%, Non-gifted; 56%) 11.3 WISC-III; FSIQ Depressive symptoms (CBCL)
Gifted adolescents scored
significantly higher on CBCL than non-gifted adolescents.
(p=.021)
Frost et al., 1989 New Zealand adolescents from unselected birth cohort of Dunedin Multidisciplinary Health and Development Study. 660 (n (DG) =10) 49% (DG; 20%) 13 WISC-R; FSIQ, PIQ Depressive disorder (DSM-III) FSIQ (M(DG)=108.30; M(NG)=109.32, p>.05) VIQ (M(DG)=106.60; M(NG)=105.14, p>.05) PIQ (M(DG)=108.50; (NG)=112.33, p>.05) Cross-sectional Glaser et al., 2011 Adolescents from the Avon Longitudinal Study of Parents and their Children (ALSPAC) 2252 51% intelligence: 8 Depression: 11, 13, 14, and 17 WISC-III; FSIQ Depressive symptoms (SMFQ) SCR (FSIQ and SMFQ) age 11 = .93 age 13 = 1.04 age 14 = 1.03 age 17 (female)=.98 age 17 (male) =1.09 Longitudinal Günther et al., 2011 Adolescents diagnosed with DD or ADHD and healthy controls 125 47% (DG=52%) 13.7 WISC-III; FSIQ Depressive disorder (DSM-IV) FSIQ (M(DG)=97; M(NG)=100, F(3, 248) =.514, p =.514) Cross-sectional Guyer et al., 2011 Adolescent girls from the Pittsburgh Girls Study 2451 100% Intelligence: 11 Depressive symptoms: 11- 14 WISC-III-R; VIQ Depressive symptoms (K-SADS-PL)
ρ(VIQ, depressive symptoms)=
-.392, p<.001 Longitudinal Hipwell et al., 2011 Adolescent girls from the Pittsburgh Girls Study 2451 100% Intelligence: 11 Depressive symptoms: 11,12 WISC-III-R; VIQ Depressive symptoms (K-SADS-PL)
ρ(VIQ, depressive symptoms)=-.29, p<.01
Horowitz & Garber, 2003 American Adolescents from public schools 240 54.2% 11.9 vocabulary and block design scales of the WISC-R; FSIQ Depressive Disorder (KSADS-E) Cross-sectional Johnson et al., 2006 11-year-old cohort of the Minnesota Twin Family Study (MTFS) 1648 53.8% M=11 Vocabulary, Information, Block design and Picture Arrangement subtests of the WISC-R; FSIQ Depressive symptoms (DICA) Girls:
r(FSIQ, depressive symptoms)=
-.06, p<.01 Boys:
r(FSIQ, depressive symptoms)=.07,
p>.01) Cross-sectional Klimkeit et al., 2011 Adolescents diagnosed with major or minor depression and healthy controls 67 (34(DG);33 (NG)) 70.1% 15.6 Similarities, Block design, Matrix Reasoning, Vocabulary, and Digit Span subtests on WISC-IV; VIQ Depressive disorder (DSM-IV-TR) VIQ
(Minor depressed group (M=94.1) Major depressed group (M=95.9) Healthy controls (M=104.2) p=.01) Cross-sectional Koolhof et al., 2007 Delinquent boys of the Pittsburgh Youth Study 170 0% 12.5 (depressive symptoms) 13 (intelligence) WISC-R; FSIQ Depressive symptoms (RMFQ) SMFQ
(Boys IQ<85; boys with IQ>85, OR=2.54)
Kounali et al., 2014 Adolescents of the Avon Longitudinal Study of Parents and Children (ALSPAC) 3498 51.6% Intelligence: 8 Depression: 18 WISC; FSIQ Depressive symptoms (CIS-R)
CIS-R, FSIQ (OR=1.00) Longitudinal
Kyte et al., 2005 Adolescents diagnosed with MDD from Cambridge child and adolescent outpatient mental health services and controls from community cohort 79 (30(DG); 49(NG) 59.5% 15.2 Vocabulary and block design subtests of WISC-III; FSIQ Depressive disorder (K-SADS-PL, DSM-IV) FSIQ (M(DG)=102.37, M(NG)=105.61, F=.20, p=.59) Cross-Sectional Maalouf et al., 2011 Adolescents diagnosed with MDD and healthy adolescents 57 71.9% (MDD: 85%, MDDrem: 75%, NG: 52.3%) 15.3 WISC-IV; FSIQ MDD (current or remitted) (DSM-IV, CDRS-R) FSIQ (M(MDD)=105, M(MDDrem)=113, (M(NG)=112, F=2.94, p=0.061) Cross-Sectional McClure et al., 1997 Non-disordered adolescent girls, divided into DG (>3 symptoms) and NG (<3 symptoms) 31 100% M=13.8 WISC-III; FSIQ, VIQ, PIQ Depressive symptoms (DSM-III-TR) FSIQ (M(DG)=100, M(NG)=111, t=2.75, p=.01) VIQ (M(DG)=101, M(NG)=110, t=2.4, p=.04) PIQ (M(DG)=100), M(NG)=111, t=2.7, p=.01) Cross-sectional
Manikam et al., 1995 Adolescents with and without intellectual disability 100 45% 13-17 Verbal part of WISC-R; VIQ Depressive symptoms (CDI, BID-R, RADS) r(VIQ, CDI)=-.219, p<.05 r(VIQ, BID-R)=-.267, p<.01 r(VIQ, RAD)=-.272, p<.01 Cross-sectional Mueller, 2009 Gifted (AHPTV>115) and non-gifted adolescents (AHPTV 85-115) 1524 (762;762) 47.4% 15.7 AHPVT Depressive symptoms (CES-D) AHPVT (M(non-gifted)=10.69 M(gifted)=8.67, t=5.758, p <.000) Cross-sectional
Park et al., 2004 Adolescents diagnosed with MDD from child and adolescent mental health services in Cambridge and healthy controls 108 (44 (MDD); 31 (MDDrem); 33 (NG)) 72.3% (MDD: 70.5%, MDDrem:74.2%, NG:64%) 14.9 WISC-II; FSIQ MDD (full or in remission) (DSM-IV) FSIQ (M(MDD)=102.0, (M(MDDrem)=99.6, M(NG)=100.8, F(3.120)=.19) Cross-sectional Rohde et al., 1994 American homeless adolescents 50 50% 18.3 WAIS-R; VIQ, PIQ Depressive symptoms (CES-D)
r(depressive symptoms, PIQ)=-.07, p>.05
r(depressive symptoms, VIQ)=-.30, p<.05 Cross-sectional Wilkinson & Goodyer, 2006 Adolescents diagnosed with MDD from community child and mental health clinics in Cambridge and Huntingdon and healthy controls 77 (MDDNM;19, MDDM; 20, ND; 38) 72.7% (MDDNM;68%, MDDM; 80%, ND; 71%) 14.9 RSPM MDD (DSM-IV) RSPM (M(MDDNM)=4.1, M(MDDM)=4.7, (M(ND)=4.6, p>.05 Cross-sectional
Note. FSIQ=Full Scale IQ, VIQ=Verbal IQ, PIQ=Performal IQ, BDI=Beck Depression Inventory, BT=Before Treatment, AT=After Treatment, AHPVT=Add Health Picture Vocabulary Test, CDI=Children’s Depression Inventory, BID=Bellevue Index of Depression, RCDS=Reynolds Child Depression Scale, CBCL=Child Behaviour Checklist, DG=Depressed Group, ND=Non-depressed group, SMFQ=Short Mood and Feelings Questionnaire, K-SADS-PL=Kiddie-Schedule for Affective Disorders and Schizophrenia for School-Age-Children-Present- and
Lifetime-Version, KSADS-E=Schedule for Affective Disorders and Schizophrenia for School-Age Children-Epidemiologic version, DICA=Diagnostic Interview for Children and Adolescents, RMFQ=Recent Mood and Feelings Questionnaire, CIS-R=Clinical Interview Schedule Revised, CDRS-R=Children's Depression Rating Scale-revised, CES-D=Center for Epidemiological Studies-Depression Scale, MDDrem=Major Depressive Disorder in remission, MDDNM=Major Depressive Disorder (No Medication), MDDM=Major Depressive Disorder (Medication),
