Dual Diagnosis

When an individual with a learning disabaility is diagnosed with a mental illness they are said to have a 'Dual Diagnosis'.

Unhelpfully the term is also used for other joint problems and mental health - such as taking illegal drugs.

It is important to say that diagnosis is not an end result.

A diagnosis may be very helpful but improvement and recovery will only happen with interventions and treatment.

The rest of this page talks about some of the problems professionals have when diagnosing mental ill health for people who have a learning disability

There are increased difficulties in diagnosis when someone has a learning disability with a mental illness. Some of these are detailed below and a brief explaination given. Families and staff need to be aware of these issues. They can then help the professionals making a diagnosis.

Limits of diagnosis of Mental Disorder within Learning Disability

Adults with a learning disability may remain at an earlier stage of 'intellectual' development than their 'physical' age. This is called intellectual distortion.

Adults with a learning disability may make things up or ‘fantasise’. (As many children do about 'invisible friends' or playing games where they are Spiderman or Superman). They can have social skills ‘above’ their actual levels of ability. (People with a learning disability can be very good at hiding their disabilities to appear less 'different' to society, such as laughing at jokes they don't understand or having routines that 'cover' their inability to tell the time). This is called psychosocial masking.

Everyday life may cause more 'stress' for an individual with a learning disability than other people, this may lead to a suggestion of mentla ill health. This is called cognitive disintigration.

Some behaviours may be normal for the individual but are interpreted as signs of a mental illness this is called a baseline exaggeration

Interviewing someone with a learning disability in order to diagnose any mental health problems can be difficult and should be undertaken by professionals with experience and understanding of these issues. Anyone communicating with someone who has a learning disability needs to consider the following factors -

- The tendancy for people with a learning disability to say 'yes' to questions asked, this is called 'acquiescence'
- The tendency to agree to with questions/statments, this is called 'suggestability'
– The tendency not be able to follow a series of questions, this is called 'order effect'
– Difficulties in reporting times/dates and history of illness, this is called 'memory'
– Individuals giving an impression of understanding (may well be an understanding of a word but not its meaning), this is called 'vocabulary'

The following pieces of information may help a medical professional make a diagnosis

- The persons age when diagnosed with a learning disability (including the cause if known, the support families and the individual received when informed and how were they informed)
- Mothers history
- Family history (of learning disability, epilepsy, autism and mental illness)
- Childhood and common ‘milestones’ (when did they sit, talk, walk etc)
- Highest points of functioning (when was the individual at their most able, best able to communicate, undertake self care tasks, travel independently etc)
- Life events (such as loss, possible abuse, institutionalisation history)
- Immediate (current) circumstances (where they live, who with, what activities/work do they undertake)
- History of complaints (physical ill health/disease, lack of appetite/sleep/motivation)

Because of the complexities of working with this client group medical professionals should be allowed to say ‘we don’t know’ rather than expected to make a firm diagnosis. There are a range of things that can be done to improve and individuals mental health regardless of the actually clinical diagnosis and some of these are shared on this website.

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