Antidepressants and cognitive impairment in the elderly.

Cognitive impairment is an important consideration in the treatment of depression in the elderly because such impairment increases with age, is a symptom of depression, and is a side effect of many antidepressant drugs. Older depressed patients are more likely to suffer acute cognitive impairment from medications including antidepressants, often superimposed on the cognitive impairment of depression. Even mild cognitive impairment can contribute to increased disability in the elderly. The occurrence of severe cognitive impairment (i.e., delirium) with tricyclic antidepressants is probably related to anticholinergic effects. Since the serotonin selective reuptake inhibitors (SSRIs) and some reversible inhibitors of monoamine oxidase (RIMAs) have little if any anticholinergic activity, these agents are expected to result in less cognitive impairment. This hypothesis is supported by a variety of comparative studies. The SSRIs and some RIMAs also have fewer additive effects with other psychoactive agents. Additional evidence suggests that some SSRIs and RIMAs may even improve cognitive functions through mechanisms separate from their antidepressant effects.