[The aging of Down's Syndrome subjects]

The normal ageing of Down's Syndrome subjects is comparable to that observed in individuals who have an equivalent cognitive deficit. However it is earlier and is related to the former intellectual level and life story of the person. Before 50 years, there is no significant reduction of memory. After this age short-term memory, the speed of information processing and selective attention weaken. These changes are similar to those in older non-Down's Syndrome defective adults, giving the impression of early ageing in Down's Syndrome subjects. In terms of autonomy in everyday life, it is possible to establish an average evolutionary profile. From 60 years old, deterioration is estimated at 45% of the score obtained at 40 years, affecting in particular the skills necessary for the carrying out daily tasks (washing, dressing, feeding without assistance.). We have little knowledge of the psychiatric evolution of this people because older handicapped people are a new group in society. In the three fields of cognition, autonomy and mental health, the ageing of Down's Syndrome subjects is very sensitive to their environment. Pathological ageing of the Down's Syndrome subject is associated with the dementia syndrome that, with varying degrees, combines disorders of the cognitive functions and behavior, modifying the personality. The clinical diagnosis of dementia is difficult to establish in the Down's Syndrome subject and opinions diverge, also it is important to comply with three rules: 1) to establish an individual base line and to observe, with the help of regular evaluations, a clear change in performance; this must be confirmed by similar modifications in daily conducts; 2) the decline depends not only on the resources of the subject, but also on the demands made by environment; 3) lasting deterioration of capacities must be clearly greater than that observable in normal ageing to signify dementia. As a function of actual age, the Down's Syndrome shows early signs of ageing compared to the general population. One notes the presence of pathological anatomic lesions from 36 years old, which are similar to those observable among patients suffering Alzheimer Disease. However it seems that about 20% of Down's Syndrome subjects do not show clinical signs of dementia 20 years later. The diagnosis, which is delicate to establish, requires an ecological process consistent over time, underlining the influence of the context and the human environment on the ageing of the Down's Syndrome subject.