Subtypes of depression in dementia.

Depression is one of the most frequent neuropsychiatric comorbidities of Alzheimer dementia (AD), affecting patents with rates from 0% to 87%. These rates vary because different populations are sampled and different instruments are used. Depressive symptoms tend to occur early, are persistent, becoming increasingly common as dementia progresses. Depression decreases the quality of life of dementia sufferers, may reduce the duration of survival and would therefore appear to be important to treat. Although questions about the interrelationships between depression and dementia have been central to the field of geriatric psychiatry for the past 30 to 40 years, clinical approaches continue to evolve through a categorical or dimensional approach.