Prospective longitudinal study of depression and anosognosia in Alzheimer's disease.

BACKGROUND

The aim was to examine the longitudinal evolution of depression and anosognosia in patients with probable Alzheimer's disease (AD).

METHOD: Sixty-two of a consecutive series of 116 AD patients that were examined with a structured psychiatric interview had a follow-up evaluation between one and two years after the initial evaluation.

RESULTS

At the initial evaluation 19% of the 62 patients had major depression, 34% had dysthymia, and 47% were not depressed. After a mean follow-up of 16 months, 58% of patients with major depression at the initial evaluation were still depressed, whereas only 28% of patients with initial dysthymia and 21% of the non-depressed patients were depressed at follow-up. During the follow-up period, all three groups showed similar declines in cognitive status and activities of daily living. At the initial evaluation, 39% of the patients had anosognosia, and there was a significant increment of anosognosia during the follow-up period.

CONCLUSIONS

While dysthymia in AD is a brief emotional disorder, major depression is a longer-lasting mood change. Anosognosia is another prevalent disorder among AD patients, and increases with the progression of the illness.