Early detection of depression and associated risk factors in adults with mild/moderate intellectual disability

Early detection of depression and associated risk factors

in adults with mild/moderate intellectual disability

Jane A. McGillivray *, Marita P. McCabe

School of Psychology, Deakin University, 221 Burwood Highway, Burwood, Vic. 3125, Australia

Received 19 August 2005; received in revised form 20 October 2005; accepted 7 November 2005

Abstract

The aim of this study was to determine the presentation and risk factors for depression in adults with

mild/moderate intellectual disability (ID). A sample of 151 adults (83 males and 68 females) participated in

a semi-structured interview. According to results on the Beck Depression Inventory II, 39.1% of participants

evinced symptoms of depression (2 severe, 14 moderate, and 43 mild). Sadness, self-criticism, loss of

energy, crying, and tiredness appeared to be the most frequent indicators of depression or risk for depression.

A significant difference was found between individuals with and without symptoms of depression on levels

of automatic negative thoughts, downward social comparison and self-esteem. Automatic negative thoughts,

quality and frequency of social support, self-esteem, and disruptive life events significantly predicted

depression scores in people with mild/moderate ID, accounting for 58.1% of the variance.

# 2006 Elsevier Ltd. All rights reserved.

Keywords: Intellectual disability (ID); Beck Depression Inventory (BDI); Depression; Risk factors

Although diagnosis can be complicated by atypical presentation (Meins, 1995; Sturmey,

1995), the existence of depression and other mood disorders in people with intellectual disability

(ID) is now widely recognized (Menolascino, 1990; Nezu, Nezu, Rothenberg, Dellicarpini, &

Groag, 1995). Prevalence rates appear to be high. Symptoms have been reported in as many as

44% (Marston, Perry, & Roy, 1997) and 57% (Meins, 1993) of clinical samples. Major

depression has been reported in between 1 and 5% of individuals with ID (Cooper, 1996) and it

has been claimed that depression may be experienced at some stage by 1 in every 10 people with

ID (Lowry, 1998). According to Cooper (1997) and Meins (1993), the prevalence rate is

approximately twice that in the general population. In a large, prospective study, Richards et al.

Research in Developmental Disabilities 28 (2007) 59–70

* Corresponding author. Tel.: +61 3 92446426; fax: +61 3 92446858.

E-mail address: [email protected] (J.A. McGillivray).

0891-4222/$ – see front matter # 2006 Elsevier Ltd. All rights reserved.

doi:10.1016/j.ridd.2005.11.001

mailto:[email protected]

http://dx.doi.org/10.1016/j.ridd.2005.11.001

(2001) demonstrated that the presence of mild ID at 15 years of age was associated with a four-

fold risk of depressive disorders later in life. It is possible that the high incidence of depression in

people with ID arises from a biological predisposition (Collacott, Cooper, & McGrother, 1992).

However, it may also result from their continuous exposure to adverse psychosocial experiences

such as social rejection, loss, and failure. Limited cognitive understanding, poor problem-solving

ability and deficits in social and interpersonal coping skills, may compound the negative impact

of these situations.

Research has demonstrated a strong positive association between intellectual ability and the

diagnosis of depressive disorders (e.g., Hurley, Folstein, & Lam, 2003). Exposure to adverse life

experiences and deficits in social relationships have both been linked with depression in people

with ID. For example, Stavrakiki and Mintsioulis (1997) established a relationship between

depressive disorders and the frequency of disruptive life events. Although people with ID appear

to experience the same type of life stressors as people without ID (Bramston, Fogarty, &

Cummins, 1999), there is a need for further investigation of the impact of these events. In

comparison to their non-disabled peers, people with ID have also been reported to have fewer

positive relationships (Rosen & Burchard, 1990; Sands & Kozleski, 1994), and receive less

emotional support from family and friends (Rosen & Burchard, 1990). Furthermore, a

relationship between low levels of social support and depression in people with ID has been

reported (Meins, 1993). However, there is a need for further investigation of this relationship,

since other findings have demonstrated that social support does not explain a significant

proportion of variance in depressive symptoms (Lunsky & Benson, 2001).

A number of cognitive factors have also been related to depression in individuals with ID. For

example, links between depression and negative social comparison (Dagnan & Sandhu, 1999), poor

self-concept (Benson & Ivins, 1992), and low self-esteem (Dagnan & Sandhu, 1999) have been

reported in this population. There is also evidence that severely depressed students with ID

demonstrate a higher level of dysfunctional cognitive self-statements than those who are not

severely depressed (Magg & Behrens, 1989). These findings suggest the need for further exami-

nation of the impact of cognitive factors on the development of depression in individuals with ID.

There has been some debate in research and clinical domains about whether it is best to use

standard diagnostic criteria (e.g., DSM-IV-TR, APA, 2000; ICD-10, WHO, 1992) to assess

depression in people with ID, or whether it is more appropriate to use informant ratings or

behavioral criteria instead of, or in addition to, standard symptomatology. It has been argued that

the inclusion of behavioral criteria makes the assessment more likely to be valid across the ID

spectrum (Clarke & Gomez, 1999; Marston et al., 1997) and that the addition of informant

information to self-report can increase the validity of diagnosis (Davis, Judd, & Herrman, 1997),

particularly in those with more severe levels of disability. However, several studies (e.g., Matson

et al., 1999; Tsiouris, Mann, Patti, & Sturmey, 2003) have demonstrated that standard diagnostic

criteria are appropriate for use with people with ID. In a recent review of studies conducted since

the mid-1990s, McBrien (2003) concluded that standard criteria are valid for the assessment of

depression in people with mild to moderate ID.

It remains important to gain a greater understanding of the patterns and characteristics of

depression symptomatology in individuals with mild/moderate ID, as well as how intrapsychic

and environmental factors impinge on depressed mood. This understanding may improve the

identification and appropriate diagnosis of depressive disorders in this population. Particular

symptom patterns may be important in alerting care-givers and practitioners to those individuals

who are ‘at risk’ of developing a depressive disorder. They may also serve to inform early

intervention initiatives and provide a foundation for the development of intervention programs.

J.A. McGillivray, M.P. McCabe / Research in Developmental Disabilities 28 (2007) 59–7060

The aim of the current study was to identify levels of depressive symptomatology in

individuals with mild/moderate ID, to examine the characteristics of mood symptoms and to

compare individuals without indications of mood disorder with those who display some

symptoms and those with significant mood symptoms on level of social support, occurrence of

recently disruptive life events, automatic thoughts, self-esteem, and social comparison.

1. Method

1.1. Participants

The sample consisted of 151 adults (83 males and 68 females) with mild/moderate ID.

Participants ranged in age from 19 to 68 years (M = 36.17, S.D. = 10.59) and were recruited

through vocational and supported employment services. These services variously provide

employment preparation, training, and light assembly line factory work for people with mild/

moderate ID. The managers confirmed that participants met the criteria for mild/moderate ID

from records on file at the agency. Language and comprehension ability appropriate to

participation in a basic interview were also prerequisites for participation. No effort was made to

recruit individuals with depressive symptoms or other psychiatric indications.

1.2. Instruments

1.2.1. Demographics

In addition to age and gender, participants were asked for information about their current

living situation and their social contact with family and friends. Participants were also asked

about any current medication use or other psychiatric intervention.

1.2.2. Beck Depression Inventory II (BDI-II) (Beck, 1996)

The BDI-II is a 21-item self-report scale designed to measure the severity of depression in

adults and adolescents aged 13 years and older. The BDI-II assesses symptoms corresponding

to the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental

Disorders—fourth edition (DSM-IV, 1994). Each item consists of four statements organized

according to the severity of their content. The participant is required to select the statement

from each item that best represents their mood over the last 2 weeks. The original wording of

each of the items was deemed simple enough for use with individuals with mild/moderate ID

and thus remained unmodified. Item 21 ‘Loss of interest in sex’ was dropped from the scale as

it was deemed to be an inaccurate measure of depression within this population. The BDI has

been successfully used to assess depression in people with ID, including a study by Lindsay

(1999), where it was used to evaluate cognitive-behavior therapy interventions for the

treatment of depression.

1.2.3. Reynolds Adolescent Depression Scale (RADS) (Reynolds, 1987)

The RADS consists of 30 items and utilizes a 4-point Likert-type response format designed to

be administered to adolescents. The RADS measures a range of symptomatology associated with

depression such as cognitive, motoric-vegetative, somatic, and interpersonal symptoms, but does

not provide a clinical diagnosis (Reynolds, 1987). All items on the RADS were retained, with

items 2, 10, 15, and 23 being modified slightly to make reference to work and other people

generally, rather than specific references to school and other students. For the purposes of this

J.A. McGillivray, M.P. McCabe / Research in Developmental Disabilities 28 (2007) 59–70 61

study, the response format was simplified to a 3-point Likert scale with the participant required to

state whether they experienced the symptom-related item ‘never’, ‘sometimes’, or ‘most of the

time’. Items were worded in the present tense in order to gauge whether the symptoms were being

experienced at the present time. The RADS has been shown to have good internal consistency

reliability and test–retest reliability, as well as good content validity and criterion-related validity

(see Reynolds, 1987).

1.2.4. Interview for Social Support in mentally retarded adults (ISS) (Meins, 1993)

The original version of the ISS was intended to be administered to direct-care staff members.

As participants in the current study were mild to moderately intellectually disabled, it was

deemed appropriate to administer the scale to the participants themselves. The original structure

of the ISS was modified for use in the current study. The first section of the interview was

substantially altered and required participants to state their frequency of contact with parents,

staff members, friends from work, friends who are also disabled, friends who are not disabled,

partners, friends from recreational groups, and any other people they interact with socially.

Frequency was measured using the following ratings: ‘daily’, ‘several times per week’, ‘once a

week’, ‘once a fortnight’, ‘once a month’, ‘once every 2–3 months’, and ‘less often’. The second

section of the ISS was not modified. Participants were required to report on the quality of each of

their social relationships using a scale of: ‘close and intimate’, ‘medium’, ‘dependent on the

situation’, and ‘none or weak’. For the purposes of this study, the ISS will be referred to in two

parts: frequency of perceived social support (FSS) and quality of perceived social support (QSS).

1.2.5. The Social Readjustment Rating Scale (SRRS) (Holmes & Rahe, 1967)

The SRRS is designed to measure the intensity and duration of changes in one’s accustomed

pattern of life as a result of significant life events (Holmes & Rahe, 1967). Ten of the most

appropriate items from the scale were utilized in the current study. Participants were asked if any

of these life events had occurred in their lives over the past 6 months. Also included was an

‘other’ option to allow for the inclusion of any other life events that were not one of the listed

items. The total number of life events was calculated for each participant.

1.2.6. Social Comparison Scale (SCS) (Allen & Gilbert, 1995)

The SCS scale is designed to measure social rank-related comparisons, social attractiveness

comparisons, and comparisons of being accepted by others. The scale provides participants with

an incomplete sentence (‘‘When I am with other people I generally feel . . .’’) and requires them

to select from a series of bipolar constructs such as left out/accepted, less competent/more

competent, inferior/superior, etc. The SCS has been modified for use with individuals with ID

(Dagnan & Sandhu, 1999). The original wording of the scale was simplified, while the meaning

of items and constructs was retained. This version has been shown to have good concurrent

validity and a psychometric structure similar to that of the original scale (Dagnan & Sandhu,

1999). In the current study, the original 10-point response scale was adapted to involve the

selection of one of the bipolar constructs to represent how they generally feel, with the option of

selecting an ‘in between’ state.

1.2.7. Rosenberg Self-Esteem Scale (RSES) (Rosenberg, Schooler, & Schoenbach, 1989)

The RSES generates a global concept of self-esteem that is considered part of the wider

concept of self-worth. The current study utilized a modified version of the 6-item version of

RSES that had already been adapted for use with individuals with ID (Dagnan & Sandhu, 1999).


The adapted scale retains the original meaning of each item, while simplifying the wording. The

original response categories were retained for use in the current study (‘never true’, ‘hardly ever

true’, ‘sometimes true’, ‘often true’, and ‘always true’). Psychometric analysis of this modified

version of the RSES has demonstrated good concurrent validity and good internal reliability

(Dagnan & Sandhu, 1999).

1.2.8. Automatic Thoughts Questionnaire—Revised (ATQ-R) (Kendall & Hollon, 1987)

The ATQ-R consists of 40 items that measure the frequency of automatic negative statements

about the self. Negative self-statements have been shown to play a critical role in various

psychopathologies, particularly depression (Schwartz & Garamoni, 1989). Ten of the most

relevant items were extracted from the ATQ-R for use in the current study. The items are

originally measured on a 5-point Likert scale. For the purposes of this study, however, the scale

was reduced to a 3-point Likert scale. Participants were required to rate the frequency of

occurrence, during the previous week, of each item on a scale of ‘not at all’, ‘sometimes’, or

‘frequently’. The authors report that the psychometric properties of the ATQ-R are comparable to

those of the original ATQ, which indicate excellent internal consistency and good concurrent

validity with measures of depression (Hollon & Kendall, 1980).

1.3. Procedure

Individual assessments were undertaken in a private location on the premises of participating

organizations. A semi-structured interview and assisted self-report format was used to guide

participants through the assessment schedule. The participant’s level of comprehension was

monitored throughout the interview process.

2. Results

2.1. Demographics

The majority of participants lived with their parents or guardians (39.1%). Forty participants

(26.5%) lived in supported accommodation, 19 participants (12.6%) lived in an independent

share house, 18 participants (11.9%) lived alone, 11 participants (7.3%) lived with their partners,

and 4 participants (2.6%) lived with siblings.

Frequent social contact with friends and family members was reported by 44.4% of

participants. Fifty participants (33.1%) reported having moderate levels of social contact, while

24 (15.9%) reported experiencing infrequent or rare social contact with family and friends. The

level of social contact experienced by 10 participants (6.6%) was unknown. Twelve participants

reported taking anti-depressant medication at the time of assessment. In 11 cases, this

medication was prescribed by their general practitioner. In the remaining case, the medication

was received from a specialist dual disability service. In all cases, there was no other psychiatric

treatment in place.

2.2. Relationships between assessment instruments

From Table 1, it can be seen that scores on the BDI and the RADS were highly correlated with

one another. Scores on the SCS were significantly correlated with scores on the BDI and RADS,

the RSES, QSS and the ATQ. Scores on the RSES were significantly related to BDI, RADS and


QSS scores. Participants’ scores on the QSS were significantly related to their scores on the BDI

and RADS, the FSS and the ATQ. Scores on the ATQ were significantly related to the BDI, the

RADS, and the SRRS.

2.3. Range of depressive symptoms

According to the recommended cut-off scores for depressive symptoms in the normal

population on the BDI-II, 92 participants (60.9%) were in the non-depressed/minimal depressed

range (score 0–10). Forty-three participants (28.5%) were in the mild depression range (score

11–16), and 14 participants (9.3%) were in the moderate depression range (score 17–25). Only

two participants (1.3%) scored in the severe depression range (score 26–60).

As a major focus of this study was to identify individuals who appeared to be ‘at risk’ of

depression, new depression groups were created in order to ensure that participants who

exhibited ‘at risk’ symptomatology were identified. Therefore, two cut-off points in the spread of

scores on the BDI-II were identified and the data were split into three groups. These groups were

labeled non-depressed (score 0–3), ‘at risk’ (score 4–11), and depressed (score 12 and above).

With the use of the new grouping, 55 individuals (36.4%) were in the non-depressed range, 48

(31.8%) reported symptoms in the ‘at risk’ range, and 48 (31.8%) reported symptoms in the

depressed range. All 12 of the individuals who reported taking anti-depressant medication were

in the depressed range.

2.4. Frequency of depressive symptoms

Table 2 shows the frequency of each of the self-reported depression symptoms included in the

BDI-II for each group. Depression symptoms were infrequently reported among the non-

depressed group. The standard symptoms of depression were most prevalent in the depressed

group. Similar symptomatology was evident in the ‘at risk’ group, although with a lower

frequency. Compared to other symptoms, guilty feelings were more pronounced in the ‘at risk’

group than the depressed group. Sadness, and also worthlessness and pessimism, were the

symptoms that most distinguished these groups.


Table 1

Pearson product moment correlations among the instruments in the assessment schedule

Variable 1 2 3 4 5 6 7

1. BDI – – – – – – –

2. RADS .64** – – – – – –

3. SCS �.30** �.24** � – – – –

4. RSES �.60** �.49** .53** – – – –

5. FSS �.05 .07 �.10 �.01 – – –

6. QSS .22** �.23** �.25** �.22** .7** – –

7. ATQ .72** .63** �.45** �.75** �.00 .23** –

8. SRRS .22** .34** .01 �.01 .12 .14 .19*

Note: A high score on frequency and quality of social contact indicates a lower frequency or lower quality of social

contact. Key: BDI, Beck Depression Inventory II; RADS, Reynolds Adolescent Depression Inventory; SCS, Social

Comparison Scale; RSES, Rosenberg Self-Esteem Scale; FSS, frequency of social support; QSS, quality of social support;

ATQ, Automatic Thoughts Questionnaire—Revised; SRRS, Social Readjustment Rating Scale.* p < .05.

** p < .01.

2.5. Differences between depression groups on psychological variables and social support

Multivariate analysis of variance (MANOVA) was used to determine the differences between

participants in the three groups (depressed, ‘at risk’, non-depressed) on levels of self-esteem,

social comparison, automatic thoughts, social readjustment, quality of perceived social support,

and frequency of perceived social support. A significant difference was found between the three

groups on the combined dependent variables: F(12, 280) = 8.75, p < .001, Wilks’ Lambda = .53,

and partial eta squared = .27. A significant difference was found between the three groups on

social comparison, F(2, 145) = 7.84, p < .001, partial eta squared = .1; levels of automatic

thoughts, F(2, 145) = 53, p < .001, partial eta squared = .42; and levels of self-esteem, F(2,

145) = 31.34, p = .001, partial eta squared = .30.

Univariate tests indicated that the depressed group had a significantly lower mean score on

social comparison (M = 9.13, S.D. = 1.4) than the ‘at risk’ group (M = 9.90, S.D. = 1.15) and the

non-depressed group (M = 9.96, S.D. = .91). The depressed group had significantly lower self-

esteem (M = 21.09, S.D. = 4.85) than the ‘at risk’ group (M = 24.80, S.D. = 3.63), who had

significantly lower self-esteem than the non-depressed group (M = 27.20, S.D. = 3.07). The

depressed group thus viewed themselves less positively when comparing themselves to other

people and had lower self-esteem than the ‘at risk’ group. The ‘at risk’ group reported lower self-

esteem than the non-depressed individuals. Univariate tests also indicated that the depressed

group had a significantly higher mean score on automatic negative thoughts (M = 7.87,

S.D. = 3.49) than the ‘at risk’ group (M = 4.02, S.D. = 3.29), who in turn had a significantly

higher mean score on automatic negative thoughts than the non-depressed group (M = 1.87,


Table 2

Percentage and rank order of each of the self-reported depressive symptoms according to group

BDI-II depression symptoms Depression

(N = 48)

‘At risk’

(N = 48)

Non-depressed

(N = 55)

% Rank % Rank % Rank

Sadness 85.5 1 33.3 6 5.5 6

Tiredness or fatigue 83.4 2 56.2 1 9.1 4

Agitation 73.0 3 45.9 2 14.5 1

Self-criticism 68.8 4 39.6 4 3.6 7

Crying 66.7 5 33.3 6 3.6 7

Loss of energy 66.7 5 35.4 5 7.3 5

Changed sleep pattern 64.6 6 39.6 4 12.7 2

Irritability 58.3 7 27.1 8 5.5 6

Loss of interest 58.3 7 27.1 8 5.5 6

Punishment feelings 56.3 8 25.1 9 3.6 7

Worthlessness 56.3 8 12.5 11 5.5 6

Past failure 54.2 9 39.6 4 10.9 3

Indecisiveness 54.2 9 29.1 7 12.7 2

Loss of pleasure 52.2 10 16.7 10 1.8 8

Concentration difficulty 50.0 11 33.3 6 3.6 7

Pessimism 47.9 12 4.2 13 5.5 6

Guilty feelings 43.8 13 43.8 3 12.7 2

Changes in appetite 41.7 14 27.1 8 5.5 6

Self-dislike 39.6 15 12.5 11 .0 9

Suicidal thoughts 23.0 16 6.3 12 3.6 7

S.D. = 1.92). In comparison to the non-depressed group, individuals in the depressed group and

the ‘at risk’ group thus reported more automatic negative thoughts.

2.6. Predictors of depression

Standard multiple regression analyses were conducted to establish whether social

comparison, self-esteem, automatic negative thoughts, social readjustment, and perceived

quality and frequency of social support (independent variables) were significant predictors of

depression scores on the BDI (dependent variable). The results of the multiple regression

analysis indicated that the above variables significantly predicted depression scores on the BDI-

II, F(6, 142) = 32.75, p < .001, accounting for 58.1% of the variance. Automatic negative

thoughts were found to have the greatest significant impact on depression scores (b = .55),

followed by quality of social support (b = .22), frequency of social support (b = �.21), self-

esteem (b = �.18), and social readjustment (b = .14). Social comparison did not contribute

significantly to the regression analysis.

3. Discussion

Self-reported symptoms of depression were identified among 39.1% of community-based

individuals with mild to moderate intellectual disability according to the recommended cut-off

scores for the normal population on the Beck Depression Inventory. The correlation between

scores on the BDI-II (Beck, 1996) and the RADS (Reynolds, 1987) confirms current opinion that

standard diagnostic criteria are valid for the assessment of depressive symptoms in people with

mild to moderate ID (McBrien, 2003), and that the more widely accepted BDI is an appropriate

screening instrument for severity of depression symptoms in this population.

Examination of the specific symptoms of depression confirms that individuals with mild/

moderate ID experience symptoms in common with standard diagnostic criteria. The most

frequently reported symptoms in the depressed group were sadness, tiredness, agitation, self-

criticism, crying, loss of energy, changes in sleeping pattern, irritability, and loss of interest in

previously enjoyed activities. The most infrequently reported symptoms in this group were

pessimism, guilt, self-dislike, appetite changes, and suicidal thoughts.

In the group whose symptoms indicated risk for depression, the most frequently reported

symptoms were tiredness, agitation, self-criticism, altered sleeping patterns, past failure, loss of

energy, sadness, crying, agitation, and concentration difficulties. The types of depression

symptoms were thus similar, although were reported less frequently in the ‘at risk’ group than in

the depressed group. The exception was guilty feelings, where although the frequency was equal

in both groups, it was the third most common symptom in individuals deemed to be ‘at risk’ of

depression, compared to a rank of 13 in the group whose symptoms indicated depression.

Sadness was the symptom that most distinguished between the groups, with a frequency of 41

individuals (85.5%) in the depression group experiencing this symptom compared with only 16

individuals (33.4%) in the ‘at risk’ group. Worthlessness and pessimism were also much less

common in the ‘at risk’ group than in the depressed group. Although the frequency was relatively

low in both groups, suicidal thoughts were also less common in the ‘at risk’ group (6.3%) than in

the depressed group (23%).

Although depression symptoms were infrequently reported among the non-depressed group,

agitation, guilty feelings, indecisiveness, and changes in sleeping patterns were the most

commonly reported symptoms in this group. In contrast to both the depressed and the ‘at risk’


groups, however, the symptoms of sadness, self-criticism, loss of energy, crying, and tiredness

were uncommon in the non-depressed group. These symptoms may be the most accurate

indicators of depression, or risk for depression, in individuals with ID. Although the BDI-II

assesses symptoms corresponding to standard diagnostic criteria (DSM-IV, APA, 1994), it

needs to be acknowledged that it is not a tool for diagnosing depression, but rather for the

assessment of the severity of depressive symptoms. It would be beneficial for future studies to

include a full diagnostic assessment, including informant report and details concerning the

sequential development of symptoms and any treatments. It remains important, however, to

establish the patterns of self-reported symptoms of depression in individuals with mild/

moderate ID. An increased awareness of these patterns may result in an increase in the

identification of individuals with depressive disorders, as well as those whose symptoms

suggest that they may be at risk.

Social comparison, self-esteem and negative automatic thoughts appear to be characteristics

that particularly distinguish individuals who appear to be at risk for, or who demonstrate

symptoms of depression from those who are not depressed. The findings of a negative

association between social comparison and symptoms of depression, and between self-esteem

and symptoms of depression, among individuals with mild to moderate ID support the findings

of Dagnan and Sandhu (1999). The way in which people with mild/moderate ID view

themselves in comparison to others and their notions of identity and self-worth may be key

factors determining whether or not these individuals become depressed, and is worthy of

attention in future research.

In common with the findings of Nezu et al. (1995), individuals with depression also had more

negative automatic thoughts than those who were deemed to be ‘at risk’ and those without

symptoms of depression. These results highlight the importance of cognitive factors in the

development of depressive symptomatology among people with mild/moderate ID.

This study demonstrated that depression scores in people with mild/moderate ID can be

predicted by various psychosocial and social support variables. Specifically, frequency of

automatic thoughts, quality and frequency of social support, self-esteem and number of

disruptive life events can predict a large degree of the variance in depression scores (58.1%). The

finding that social comparison was not a significant predictor of depression was most likely due

to the inclusion of self-esteem in the regression model. As social comparison and self-esteem are

conceptually similar, it is likely that self-esteem accounted for much of the variance that might

have been explained by social comparison. The number of life events experienced by an

individual over a 6-month period was also a predictor of depression scores. This suggests that

people with ID may not be mentally or emotionally equipped to manage change or unexpected

occurrences in their lives. The development of strategies to help people with ID better cope with

change in their lives may protect them against the development of depression. Future research

should explore this proposal further.

The finding that infrequent and poor quality social support was associated with higher levels

of depression symptomatology is consistent with the results of previous research (Meins, 1993;

Reiss & Benson, 1985). Although other researchers (e.g., Lunsky & Benson, 2001) have reported

that social support was not a significant predictor of depression in individuals with mild ID, this

possibly reflects different characteristics of the samples. Participants in Lunsky and Benson’s

study all lived in environments where staff support was provided on a regular basis. In contrast,

participants in the present study resided in a variety of living environments where contact with

others was likely to be less consistent. Future research with larger populations and enabling

comparison between different living environments is recommended.


The impact of quality of social support on whether or not a person with ID is likely to

become depressed emphasizes the importance of people with ID feeling emotionally supported

and connected to others. The possibility that the closeness of a relationship may be more

important than the frequency of contact is of interest. Of course, this may reflect the difficulty

that some participants appeared to have reported inaccurately the frequency of their contact

with family and friends. However, it also suggests the possibility that there may be some

negative impact arising from a greater frequency of certain types of social contact for some

individuals with ID. Negative or fraught relationships have been shown to be a significant

source of stress for this population (Bramston et al., 1999). Furthermore, social strain, as

opposed to social support, has been linked with depression and reports of somatic complaints

(Lunsky & Benson, 2001). There is clearly a need for more research to identify the particular

aspects of social relationships which may serve to decrease the risk of depression in individuals

with intellectual disability.

The findings of this study are limited by the small sample size, the possibility of selection bias

and a lack of generalizability. The use of modified instruments, without evidence that they remain

psychometrically intact, is also a major limitation. However, this study indicates that frequency

of negative automatic thoughts, low self-esteem, high numbers of negative life events, low

quality of social support, frequency of social support, and downward social comparison are likely

risk factors for the development of depression among individuals with mild/moderate ID. These

variables need to be explored further in research.

Several practice recommendations arise from this study. People with ID should be routinely

screened for the presence of depression, and its risk factors. Primary health care providers,

particularly GPs, need to be trained to identify risk factors and to undertake brief screening for

depression in individuals with ID. However, because many people with ID do not regularly visit

medical practitioners or mental health services, it would also be desirable for general staff and

other health care providers who are located within the context of the workplace and community

settings frequented by individuals with ID to also receive training. There is also a need for the

development and implementation of intervention programs to address the factors that appear to

contribute to depression in this population and for these factors to serve as the basis of programs

to treat the symptoms of depression among people with ID.

Acknowledgements

We wish to thank beyondblue: the national depression initiative and the Victorian Centre of

Excellence for their generous support of this research.

References

Allen, S., & Gilbert, P. (1995). A social comparison scale: Psychometric properties and relationship to psychopathology.

Personality and Individual Differences, 19, 293–299.

American Psychiatric Association (APA). (1994). Diagnostic and statistical manual of mental disorders (DSM-IV) (4th

ed.). Washington, DC: Author.

American Psychiatric Association (APA). (2000). Diagnostic and statistical manual of mental disorders-text revised

(DSM-IV-TR). Washington, DC: Author.

Beck, A. (1996). Beck Depression Inventory-II (BDI-II). The Psychological Corporation. San Antonio Harcourt Brace and

Company.

Benson, B. A., & Ivins, J. (1992). Anger, depression and self-concept in adults with mental retardation. Journal of

Intellectual Disability Research, 36, 169–175.


Bramston, P., Fogarty, G., & Cummins, R. A. (1999). The nature of stressors reported by people with an intellectual

disability. Journal of Applied Research in Intellectual Disabilities, 12, 1–10.

Clarke, D. J., & Gomez, G. A. (1999). Utility of modified DCR-10 criteria in the diagnosis of depression associated with

intellectual disability. Journal of Intellectual Disability Research, 43(5), 413–420.

Collacott, R. A., Cooper, S. A., & McGrother, C. (1992). Differential rates of psychiatric disorders in adults with downs

syndrome compared with other mentally handicapped adults. British Journal of Psychiatry, 161, 671–674.

Cooper, S. A. (1996). Depressive episodes in adults with learning disability. Irish Journal of Psychological Medicine, 13,

105–113.

Cooper, S. A. (1997). Epidemiology of psychiatric disorders in elderly compared with younger adults with learning

disabilities. British Journal of Psychiatry, 170, 375–380.

Dagnan, D., & Sandhu, S. (1999). Social comparison, self-esteem and depression in people with intellectual disability.

Journal of Intellectual Disability Research, 43(5), 372–379.

Davis, J. P., Judd, F. K., & Herrman, H. (1997). Depression in adults with intellectual disability. Part 2: A pilot study.

Australian and New Zealand Journal of Psychiatry, 31(2), 243–251.

Hollon, S. D., & Kendall, P. C. (1980). Cognitive self statements in depression: Development of an automatic thoughts

questionnaire. Cognitive Therapy and Research, 4, 383–396.

Holmes, T. H., & Rahe, R. H. (1967). The Social Readjustment Rating Scale. Journal of Psychosomatic Research II, 213–

218.

Hurley, A. D., Folstein, M., & Lam, N. (2003). Patients with and without intellectual disability seeking outpatient

psychiatric services: Diagnoses and prescribing pattern. Journal of Intellectual Disability Research, 47, 39–50.

Kendall, P. C., & Hollon, S. D. (1987). In K. Corcoran, & J. Fischer (Eds.), Measures for clinical practice: A sourcebook.

New York: Free Press.

Lindsay, W. R. (1999). Cognitive therapy. The Psychologist, 12, 238–241.

Lowry, M. A. (1998). Assessment and treatment of mood disorders in persons with developmental disabilities. Journal of

Developmental and Physical Disabilities, 10(4), 387–406.

Lunsky, Y., & Benson, B. A. (2001). Association between perceived social support and strain, and positive and negative

outcome for adults with mild intellectual disability. Journal of Intellectual Disability Research, 45, 106–114.

Magg, J. W., & Behrens, J. T. (1989). Depression and cognitive self-statements of learning disabled and seriously

emotionally disturbed adolescents. The Journal of Special Education, 23(1), 17–27.

Marston, G. M., Perry, D. W., & Roy, A. (1997). Manifestations of depression in people with intellectual disability.

Journal of Intellectual Disability Research, 41(6), 476–480.

Matson, J. L., Rush, K. S., Hamilton, M., Anderson, S. J., Bamburg, J. W., Baglio, C. S., et al. (1999). Characteristics of

depression as assessed by the Diagnostic Assessment for the Severely Handicapped—II (DASH-II). Research in

Developmental Disabilities, 20, 305–313.

McBrien, J. A. (2003). Assessment and diagnosis of depression in people with intellectual disability. Journal of

Intellectual Disability Research, 47, 1–13.

Meins, W. (1993). Prevalence and risk factors for depressive disorders in adults with intellectual disability. Australia and

New Zealand Journal on Developmental Disabilities, 18, 147–156.

Meins, W. (1995). Symptoms of major depression in mentally retarded adults. Journal of Intellectual Disability Research,

39(1), 41–45.

Menolascino, F. J. (1990). Mental retardation and the risk, nature and type of mental illness. In A. Dosen, & F. J.

Menolascino (Eds.), Depression in mentally retarded children and adults. Leiden: Logon Press.

Nezu, C. M., Nezu, A. M., Rothenberg, J., Dellcarpini, L., & Groag, I. (1995). Depression in adults with mild mental

retardation: Are cognitive variables involved? Cognitive Therapy and Research, 19, 227–239.

Reiss, S., & Benson, B. A. (1985). Psychosocial correlates of depression in mentally retarded adults: I. Minimal social

support and stigmatization. American Journal of Mental Deficiency, 85, 229–242.

Reynolds, W. M. (1987). Reynolds Adolescent Depression Scale: Professional manual. Odessa, FL: Psychological

Assessment Resources.

Richards, M., Maughan, B., Hardy, R., Hall, I., Strydon, A., & Wadsworth, A. (2001). Long-term affective disorder in

people with a mild learning disability. British Journal of Psychiatry, 179, 523–527.

Rosen, J., & Burchard, S. (1990). Community activities and social support networks: A social comparison of adults with

and without mental retardation. Education and Training in Mental Retardation, 25, 193–204.

Rosenberg, M., Schooler, C., & Schoenbach, C. (1989). Self-esteem and adolescent problems: Modeling reciprocial

effects. American Sociological Review, 54, 1004–1018.

Sands, D. S., & Kozleski, E. B. (1994). Quality of life differences between adults with and without disabilities. Education

and Training in Mental Retardation, 28, 119–131.


Schwartz, R. M., & Garamoni, G. L. (1989). Cognitive balance and psychopathology. Clinical Psychology Review, 9,

271–294.

Stavrakiki, C., & Mintsioulis, G. (1997). Anxiety disorders in persons with mental retardation: Diagnostic, clinical, and

treatment issues. Psychiatric Annals, 27, 182–189.

Sturmey, P. (1995). DSM-III-R and persons with dual diagnoses: Conceptual issues and strategies for future research.

Journal of Intellectual Disability Research, 39, 357–364.

Tsiouris, J. A., Mann, R., Patti, P. J., & Sturmey, P. (2003). Challenging behaviours should not be considered as depressive

equivalents in individuals with intellectual disability. Journal of Intellectual Disability Research, 47, 14–21.

World Health Organization (WHO). (1992). The ICD-10 classification of mental and behavioural disorders: Clinical

descriptors and diagnostic guidelines. Geneva: Author.


Documents

Early detection of depression and associated risk factors in adults with mild/moderate intellectual disability