Understanding depressive symptoms in adults with mild intellectual disability


Information from family members, and carers can be used to assist in health and medical assessments for people with intellectual disability. Carer reports about a person’s health and well-being are particularly important, especially if the individual has difficulty in expressing how they are feeling or describing any symptoms they may have. This includes when a person may be experiencing depression. Information from carers may differ though to what the individual may be feeling and thinking.

Comprehensive information from a range of sources will assist in obtaining effective treatment, as an area of difficulty for doctors is treating people with intellectual disability and behavioural or psychiatric conditions (Phillips, Morrison & Davis, 2004).

In a recent study by Mileviclute and Hartley (2015), information about a person’s symptoms of depression were explored. The authors had two aims:

  1. to find out if there was a difference between a person with a mild intellectual disability’s self-report of his or her depressive symptoms and carers’ descriptions of symptoms.
  2. to find out if socio-demographic factors, such as age, gender, level of IQ and co-existing psychiatric illness influenced the presentation of a person’s depression.
Information from a range of sources can help diagnosis

Information from a range of sources can help diagnosis


For the first aim, the authors compared questionnaires that were filled in by people with mild intellectual disability to a questionnaire filled in by carers. They then created categories of similar items in the questionnaires so they could make comparisons.

These categories were:

  • somatic (e.g., feeling tired, loss of appetite, insomnia)
  • cognitive (e.g., self-blame, suicidal thoughts, helplessness, anxiety)
  • affective (e.g., sad/crying, aggressive, worried)

For the second aim, the authors used a statistical test called regression analysis to find out if there was an association between socio-demographics and the depressive symptom categories.


Mileviciute and Hartley (2015) found that:

  • People with intellectual disability reported higher frequency of affective and cognitive symptoms than carers reported.
  • Somatic symptoms are more recognisable to others than affective and cognitive symptoms, and are thus a critical indicator of depression
  • Older adults had higher frequency of somatic symptoms than younger people, as reported by carers. However, the opposite occurred on self-reports.
  • People with lower IQ reported greater frequency of symptoms
  • There was a negative association between age and frequency of cognitive depressive symptoms (older people had a lower frequency of depressive symptoms)
Carers tended to focus on external signs rather than internal ones

Carers tended to focus on external signs rather than internal ones


Mileviciute and Hartley’s study provides valuable insight into the differences between staff reports of depression, versus self-reports by people with intellectual disability.

Staff were more likely to focus on somatic symptoms rather than the other more internalised symptoms. This is of course understandable.

However, what this study highlights is the vital importance of asking people with disability about their feelings and emotions, as there were differences between what individuals said about themselves, compared to what carers said.

Strengths and Limitations

There were some limitations with this study, some of which were acknowledged by the authors and others which weren’t. The authors acknowledged that all of the participants who were diagnosed with depression were currently taking anti-depressant medications. This may have influenced both the self-reporting of symptoms as well as the observed symptoms by carers.

However, not acknowledged were problems with the use of questionnaires to elicit such information. There is some research evidence to suggest that acquiescence is a frequent problem when people with an intellectual disability complete questionnaires – there is a tendency to provide what they think is the ‘right’ answer (Finlay & Lyons, 2001).

Another limitation was the way in which the authors determined if participants with intellectual disability were able to reliably use a three-point Likert scale on a questionnaire. Participant’s ability was assessed in two ways:

  1. participants were asked to label size orders of containers with varying amounts of water.
  2. they were asked to rate their favourite food preferences on a written scale.

The authors only assessed individuals’ capabilities to use a Likert scale using very basic and concrete concepts.They did not assess individuals’ ability to recognise different emotional states, or their understanding of these, or the various concepts they were asked about.

Complex concepts were included in the questionnaires, such as: avoidance, self-defeat, decision making processes, etc. Presumably for some people with an intellectual disability, these concepts may have been difficult to grasp.

Recommendations for practice

Including self-reports of depressive symptoms in the treatment of depression for people with intellectual disability offers valuable insight, and can aid in diagnosis and treatment. However, the use of questionnaires to elicit information may be less than ideal.

Information regarding a person’s depressive symptoms can be obtained in a variety of ways, so as to minimise the likelihood of acquiescence and to obtain a more holistic picture. Interviews or supportive meetings can also be used.

It is important to ask the individual about their feelings and emotions

It is important to ask the individual about their feelings and emotions


Mileviciute, I., Hartley, S.L., (2015) Self-reported versus informant-reported depressive symptoms in adults with mild intellectual disability, Journal of Intellectual Disability Research Vol 59 (2), 158-169 [abstract]


Finlay, W. M. L.; Lyons, E. (2001) Methodological issues in interviewing and using self-report questionnaires with people with mental retardation. Psychological Assessment, Vol 13(3), 319-335.

Phillips, A., Morrison, J., Davis, R.W., (2004) General practitioners’ educational needs in intellectual disability health, Journal of Intellectual Disability Research. Vol 48 (2), 142–149 [abstract]

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Louise Phillips

Louise worked for many years supporting people with learning disability and challenging behaviour in a direct support capacity. Louise is currently a PhD candidate at LaTrobe University in Melbourne Australia. She is undertaking a qualitative project; investigating how support staff respond to challenging behaviour and why they respond as they do. Louise is also a Research Assistant with the Living with Disability research team at LaTrobe University, and is involved in researching Active Support implementation and Practice Leadership in residential group homes across Australia.

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