Episodic remembering in a population-based sample of nonagenarians: does major depression exacerbate the memory deficits seen in Alzheimer's disease?

Abstract

Population-based samples of normal old adults and people with major depression (MD), Alzheimer's disease (AD), and coexisting MD and AD (MD + AD) between 90 and 100 years of age were assessed in face recognition, word recall, and object recall. Results indicated a consistent pattern across tasks: no differences between the normal old and the MD participants or between the AD and MD + AD participants in any task, a clear performance decrement in the AD and MD + AD participants in all task variables reflecting long-term episodic memory, and no group differences in those variables reflecting short-term memory. These data suggest that depression in very old age may not exacerbate the episodic memory deficit that accompanies AD. Further, differences between normal old and MD participants in episodic memory tasks appear to be negligible among the oldest old. The general lack of effects of MD may be due to the fact that those symptoms of this disease that are most likely to affect memory functioning (e.g., loss of energy, concentration difficulties) are common in AD as well as in nondepressed people in the 10th decade of life.