Gary Donohoe, MPsychSC, Psychologist in clinical training reviews a series of articles on the manifestations and diagnosis of psychiatric disorders in people with severe intellectual disability.


When is someone ‘suffering from their nerves’? What are the signs that someone has a mental illness? While physical illness can often be easily recognised (a fever, a stomach pain), mental health problems can be difficult to diagnose. In recent decades mental health professionals have become more aware of the prevalence of psychiatric disorders among persons with intellectual disability, which is in fact higher than in the general population (Cambell and Malone 1991). Despite this increased awareness, recognising the presence of mental disorders like depression can be quite challenging.

Because there are no definitive measures (e.g. blood tests) for psychological disorders such as depression and anxiety, clinicians rely heavily on information provided by clients and their families. Through careful assessment, changes in a client’s pattern of thinking and behaviour become evident. Increase in negative thoughts, difficulty in seeing the positive, reduction in activity, and changes in sleeping pattern can all serve as indicators of depression.

However, for clients with learning disabilities, many of whom have difficulties communicating their thoughts and emotions, this investigative work is more complicated. While the symptoms of depression among people with mild/moderate intellectual disability are similar to those in people who do not have a disability, for people who are non-verbal and have a severe/profound intellectual disability symptom detection is much more challenging.

In recent years a number of researchers have sought to explore alternative means to detect the presence of depression among this group. Their studies have suggested that, in addition to disturbance in sleeping and eating (depressive symptoms commonly seen in the general population), specific behavioural signs may demonstrate depression among people with severe and profound disabilities. These include problems such as loss of interest and social isolation, agitation, aggression and self-injurious behaviour. In other words, for the person with a severe or profound learning disability, acting in an aggressive or agitated manner may communicate feelings similar to a person with verbal communication saying that they feel life is hopeless.

On the basis of these suggestions, New York psychiatrist Dr John Tsiouris undertook a study which reviewed the case-notes of 150 people with learning disabilities to establish whether these behavioural signs could be detected. In his report, published in a recent edition of the Journal of Intellectual Disability Research, Dr Tsiouris found evidence of many of these behavioural signs for the group as a whole. Most interestingly, when compared with those with mild/moderate disability, those with severe/profound disability showed a much higher rate of these behavioural signs. Two-thirds of the group showed at least some of these behavioural signs. For example, while 75% of the severe/profound group showed symptoms of loss of interest, none of the mild/moderate group did. Similar findings were noted for social isolation and aggression. By contrast, self-injurious behaviour was seen with similar frequency in both groups.

Dr Tsiouris points out that such behavioural signs can only be considered as indicative of depression when taken in conjunction with standard criteria such as changes in sleeping and eating. Doing so, however, provides useful tools for detecting depressive disorder among those with severe and profound disabilities. Such evidence speaks powerfully of the importance of paying close attention to what is being communicated through changes in behaviour. After all, without verbal skills, how else can a person say how they are feeling except by what they do?

Seeking to understand the purpose of a behaviour can be important in helping someone feel supported. It enables us to feel less challenged by difficult behaviours such as aggression and self-harm and to respond more positively to the underlying needs. This is important because support from those around us is a major factor in mental illnesses such as depression. This can occur in two ways. Firstly, social support can be a protective factor against depression. Secondly, the stress of negative interactions, for example with family members, is associated with an increased risk of depression. This is known to researchers as ‘social strain’.

In a recent article on people with learning disabilities’ perception of social support, Lunsky and Benson, two researchers at the University of Toronto, found a strong association between social strain and depression. By contrast, they also found that perceived social support was associated with better quality of life. The suggestion is that, while the support of others is really important for getting the most out of life, negative social interactions can cause people to feel bad about themselves and their life situation.

People often tell us how they feel by what they do, rather than by what they say. While it is often difficult to know what a behaviour means, how we respond can have a major impact on how they feel. And while behavioural signs such as aggression and disinterest may be used to communicate many different things, they may be important indicators of depression.