[Depression and dementia].

Data from the literature devoted to the relationships between dementia and depression are controversial on account of numerous methodological biases (community studies or from neurological or psychiatric departments), categorical versus dimensional approaches and variability of assessment tools for depression, aim of the study (depression versus dementia or versus Alzheimer's disease, AD). The difficulty to discriminate depression from AD is largely overestimated due to the confusion between depression, depressive symptomatology and apathy. The distinction is greatly facilitated by taking into account the qualitative differences of the memory deficits and cerebral imagery. Distinction of depression from frontotemporal or subcortical dementias could be much more difficult. Relationships between depression and AD are controversial. Most reports of depression as a risk factor for AD in the subsequent years, actually describe depressed symptomatology linked to apathy in preclinical AD. However, some studies found a relationship between AD and depression occurring more than 10 years before the onset of AD symptomatology, suggesting some common risk factors. The so-called symptoms of depression in AD are more related to apathy and affective disturbances than to dysphoria. The frequency of major depressive episode (MDE), greatly varies according to studies, but the frequency of suicide is low. Depression in dementia is related to neurobiological factors as well as to psychological mechanisms. Therefore, its treatment should associate antidepressant drugs and psychological support directed to the patient and family.