Assessment of Schizophrenia in People with Intellectual Disability

Quality of Symptoms

 It may be difficult eliciting ‘first rank’ symptoms in people with intellectual disability (a running commentary on the person’s behaviour or thoughts, or two or more voices conversing with each other). This can be because the symptoms are difficult to assess, difficult for the person to recognise and communicate and it may be they occur less in people with intellectual disability.  The symptoms can be simpler in their content, appear somewhat naive and tend to be less systematised than in the general population. This is because symptoms are affected by the person’s developmental level, cognitive functioning and life experiences. Persecutory delusions may be in the form of beliefs that people are trying to get them in to trouble or telling lies about them, rather than trying to kill them; grandiose delusions might be that the person has a job when in reality they have never had regular employment; auditory hallucinations may simply be voices calling the person names rather than more complex commentary or conversations and visual hallucinations may be about ghosts, witches or other story book images. This is important as the simpler content may lead clinicians to understand the symptoms as fantasy or make believe and not recognise that an illness is present.  In the general population psychotic experiences often develop into complex beliefs as the person attempts to explain and rationalise their abnormal experiences. For example a person with schizophrenia may have a psychotic belief that they have special powers leading to beliefs that the security services are monitoring them and that this is occurring through the television set with family members also being involved. This creation of a delusional system is less likely in people with ID and the lack of expansion can also lead clinicians to underestimate the symptom severity.  As part of a usual psychiatric assessment clinicians may attempt to dissuade a patient from their delusional beliefs - to establish whether they really are unshakeable beliefs. Under such circumstances a person with intellectual disability may feel pressured to agree with the clinician, especially if it is suggested that such ideas are unreasonable, illogical or silly. Such acquiescence should not exclude the diagnosis of psychosis as a person with ID may have felt incompetent in a variety of environments in the past and have learned to agree with professionals. A different approach is required and it will be important to note whether the person reverts to their original beliefs and if these beliefs are consistent over time.  Symptoms of mental illness are also described as being pervasive and impacting on most aspects of a person’s life and function. In practice it is apparent that there may be certain situations where a person’s psychotic symptoms are less evident. This is true in people with ID with fewer symptoms occurring in less stressful environments where the person receives high levels of support, has positive interactions and can participate in their preferred activities.

Level of intellectual disability

 In individuals with severe and profound intellectual disability symptoms can be very different from those experienced by the rest of the population. As the severity of intellectual disability increases understanding and communication may decrease. The assessment process will increasingly depend on observations of behaviour rather than reported symptoms. It is not possible, for example, to assess thought disorder in someone who does not speak, nor can the person describe psychotic symptoms such as delusions or hallucinations. Observed behaviours which might suggest psychotic illness in someone with ID include:  Appearing distracted or preoccupied  Staring off to the side during conversation  Nod and gesture as though listening to a conversation when alone  Pointing, gesturing or reaching out when there is nothing there  Sudden unexplained outbursts  Appearing worried, scared and watchful  Unable to attend to self-care as normal (eating, dressing, toileting)  Not following usual routine or participating in activities  Disorganised behaviour  Breaking things in particular electronic devices, television, radio and computer equipment  Problem behaviours can occur during psychotic illnesses and these can be the only observable signs. Longstanding problem behaviours may increase in frequency or duration.