Affectivité et démence

Abstract

Mood disorders are frequent in dementia and often precede cognitive dysfunction. Their prevalence is difficult to establish because of differences in definitions, methodology, scales or origin of information. They result from a dysfunction in fronto-subcortical, striato-limbic and paralimbic structures involved in neurodegenerative disorders. In elderly people, 40-70% of the population has a mood disorder, and among them 15-25% a major depression. Accompanied cognitive deficits constitute the debated entity of pseudodementia or dementia syndrome of depression. This is a fuzzy field and the reversibility of the cognitive deficits is far from having been proved, 60-89% of tardive depression evolve toward dementia and only 5% of depressive state are identified as the first symptom of dementia or interpreted as changes in personality; no test or brain imaging technique can help in the diagnosis. Depression is the second most symptom in Alzheimer's disease and a common presenting symptom with a continuum between dysthymia (20-50%) and major depression (10-30%) and has even been interpreted as a factor for Alzheimer's disease. Apathy (50-80%), verbal aggressivity, agitation (40-60% ), emotional lability or abrupt changes in mood, irritability and violence are commonly associated with mood disorders in Alzheimer's disease. Anxiety is frequent (4%), but manic states or euphoria are exceptional. With the evolution of the disease, the prevalence of depression decreases. In Lewy body disease the prevalence of depression is the same as in Alzheimer's disease, anxiety is less frequent, violence is reported in 20%, psychomotor agitation in 60%. In fronto-temporal dementia changes in personality and social or instinctual behaviour are accompanied by some degree of depression (80% ), apathy (50-70%), disinhibition, insouciant euphoria (10-30%), loss of empathy or concern about the consequence of one's acts, blunting of affectivity, irritability or disorders of impulse control and sometimes manic states. In vascular dementia depression is more frequent than in Alzheimer's disease, apathy and mood fluctuations also. AIDS dementia is mostly apathetic or manic. Parkinsonism and dementia associate apathy and depression, anxiety and dysphoric states. In Huntington's chorea, disorders of impulse control, anxiety and severe depression with a risk of suicide 8-10 times higher than in the normal population are frequent in the beginning of the disease. Apathy is generally found in terminal stages of the disease. Multiple sclerosis with cognitive deficits, dementia due to sarcoidosis, Behcet's, Whipple's and Sjogren's diseases and idiopathic calcification of the basal ganglia are associated with depression, aggressivity, irritability and manic states. Occasionally, B 1 2 deficiency can present with depression or mania, hydrocephaly is commonly associated with depression and apathy. Wilson's disease is known to present with disorders of impulse control, depression, anxiety, emotional lability, aggressivity, apathy or manic states. Treatment of mood disorders in dementia generally responds to tricyclic antidepressants, SSRIs or adrenergic selective antidepressants. Agitation is best treated with clozapine, quetiapine, olanzapine and risperidone, but the latter and classic neuroleptics may be harmful in Lewy body disease. Paradoxical reactions to sedatives are sometimes encountered, but diazepines and clomethiazole may be used.