Depression in Alzheimer's disease: phenomenology, clinical correlates and treatment.

Depression is one of the most frequent comorbid psychiatric disorders in Alzheimer's disease and other dementias, and is associated with worse quality of life, greater disability in activities of daily living, a faster cognitive decline, a high rate of nursing home placement, relatively higher mortality, and a higher frequency of depression and burden in caregivers. Depression in Alzheimer's disease is markedly under-diagnosed, and most patients with depression are either not treated or are on subclinical doses of antidepressants. This is related to the lack of validated diagnostic criteria and specific instruments to assess depression in dementia. Apathy and pathological affect-crying are the main differential diagnoses of depression in Alzheimer's disease. Left untreated, major depression in Alzheimer's disease may last for about 12 months. Recent randomized controlled trials demonstrated the efficacy of sertraline and moclobemide to treat depression in Alzheimer's disease. Other psychoactive compounds may be useful as well, but careful consideration must be given to potentially serious side-effects.