Results of various studies using comprehensive neuropsychologic batteries suggest that elderly patients who are depressed have cognitive impairment, particularly in visuospatial ability, psychomotor speed and executive functioning. The executive deficits are associated with late-onset depression and vegetative symptoms. Although the correlation between depression in the elderly and cognitive function have been established, no current studies have evaluated the impact of treatment for depression on cognitive function in persons in this age group. Butters and colleagues examined the cognitive response to treatment in patients with late-life depression.

Participants enrolled in the study included elderly patients who met the Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV) criteria for major depression and a comparison group of elderly subjects. Some patients had cognitive impairment, but none met the Alzheimer's disease diagnostic criteria or DSM-IV criteria for dementia. All participants were evaluated before the study using established instruments to measure depression, functioning status and dementia ratings. They were reassessed again at the end of the study. Participants in the group with depression were randomly assigned to treatment with nortriptyline or paroxetine.

Participants who responded to treatment for depression showed a small improvement in overall cognitive function at the end of the trial. Participants who had cognitive impairment before the study showed improvement in conceptualization and initiation/preservation domains. Despite these improvements in cognitive function, subjects with cognitive dysfunction at baseline remained mildly impaired after treatment.

The authors conclude that elderly patients with depression and cognitive impairment may experience improvement in their cognitive function within certain domains after treatment with antidepressants. However, these patients may not reach normal performance levels, particularly in memory and executive functions. Elderly patients who do not return to a normal level of function at the end of treatment are at higher risk for developing progressive dementia.