Since Langdon Down (1828 – 96) described the syndrome in 1866, there has been a common perception that persons with Down syndrome have a friendly, amiable personality (40). Studies confirm good general social skills with social understanding commensurate with mental age and a special ability to imitate gestures and mimic (41, 42). Persons with Down syndrome appear to develop behavioural and emotional problems less frequently in their childhood and adolescence than persons with other causes of intellectual disability. From the age of 20 – 30 however, a growing incidence of anxiety and depression is found, with symptoms such as withdrawal, mutism, psychomotoric retardation, subdued moods, passivity, loss of appetite and sleeping disorders (11). Hallucinations associated with serious depressions are not unusual. Obsessive-compulsive disorders with retarded movement, tics and freeze responses occur relatively frequently, particularly in women. Bipolar disorders and schizophrenia, on the other hand, appear to occur relatively seldom in persons with Down syndrome. However, there is a relatively high incidence, in women in particular, of unspecified psychoses characterised by a low level of aggression, but a high level of visual and auditory hallucinations (40). At the same time, persons with Down syndrome often have a strong imagination which makes it difficult to distinguish fantasies from hallucinations (43). Other signs of psychosis in patients with Down syndrome are withdrawal, mutism and retarded movement, a symptomatology similar to that of depression.
Because of their greater susceptibility to disease and generally shorter life expectancy, persons with Down syndrome often experience that close friends and fellow members of collectives die. An intense fear that their parents will die is not uncommon either. Complicated grieving processes may ensue, followed by prolonged helplessness, anxiety and depression. Good psychological preparation and support are important for preventing this.