The Construct of Minor and Major Depression in Alzheimer's Disease.

Objective: This study examined the frequency of major and minor depression in Alzheimer's disease and determined whether these types of depression have a different functional and psychopathologi- cal impact and whether there is a change in the prevalence of major and minor de- pression throughout the stages of Alzhei- mer's disease. Method: A consecutive series of 670 pa- tients with probable Alzheimer's disease were assessed with the Structured Clinical Interview for DSM-IV; specific instruments to rate the presence and severity of depres- sion, anxiety, apathy, irritability, delusions, pathological affective crying, performance of activities of daily living, and social func- tioning; and a standardized neuropsycho- logical evaluation. Diagnoses of major and minor depression were generated from DSM-IV criteria. Results: Twenty-six percent of the pa- tients had major depression, 26% had minor depression, and 48% were not depressed. Major depression was signifi- cantly associated with sad mood in all three stages of the illness, although this as- sociation dropped significantly for minor depression in severe Alzheimer's disease. Both major and minor depression were significantly associated with more severe psychopathology, functional impairments, and social dysfunction. Depressive symp- toms that most strongly discriminated be- tween Alzheimer's disease patients with and without sad mood were guilty ide- ation, suicidal ideation, toss of energy, in- somnia, weight loss, psychomotor retarda- tion/agitation, poor concentration, and loss of interest. Conclusions: Our study demonstrates that DSM-IV criteria for major and minor depression identify clinically relevant syndromes of depression in Alzheimer's disease, mild levels of depression can pro- duce significant functional impairment, and the severity of psychopathological and neurological impairments increases with increasing severity of depression. [ABSTRACT FROM AUTHOR]