Cognitive and Psychomotor Effects of Antidepressants with Emphasis on Selective Serotonin Reuptake Inhibitors and the Depressed Elderly Patient

Cognitive and psychomotor impairment are important considerations in the treatment of depression in the elderly due to both the underlying slowing of cognitive and psychomotor processes as a normal function of aging and the superimposed deficits associated with the disease itself. Only the latter are reversible with effective antidepressant therapy. Yet certain antidepressant drugs possess sedating and otherwise impairing side effects that can further degrade the patients’ functional abilities. Several studies have demonstrated that tricyclic antidepressants (TCAs) produce impairment in cognitive and psychomotor function that is not just due to sedation. Antidepressants with relatively non-sedating, nonimpairing profiles, such as the selective serotonin reuptake inhibitors (SSRIs) may be preferred in depressed patients. However, differences are emerging amongst the group with respect to their effects on cognitive and psychomotor function. Differential SSRI effects are being noted on both the degree of cognitive impairment in healthy volunteers and rates of cognitive and psychomotor improvement in depressed patients. Furthermore, SSRIs vary in their potential to inhibit the cytochrome P450 enzyme mediated metabolism of many centrally acting medications. This may be an indirect mechanism whereby SSRIs induce cognitive and psychomotor problems. The differences amongst the cognitive profiles of SSRIs and other newer antidepressant drugs are more subtle than the differences between these agents and TCAs. There is a need for well designed comparative studies to characterize the differential cognitive profiles of SSRIs and other newer antidepressants, and more importantly to show the clinical relevance, if any, of these differences (German Journal of Psychiatry; 1999;2:1-28).