Verbal learning by major depressive disorder patients during treatment with fluoxetine or amitriptyline.

After 1 week of a single-blind placebo period, and prior to being randomly assigned to receive treatment with either fluoxetine or amitriptyline, patients meeting strict criteria for a diagnosis of major depressive disorder were given an auditory verbal learning test of working memory, and a blood sample was drawn. After 3 weeks of drug treatment with either amitriptyline or fluoxetine, the patients' symptoms were evaluated, the verbal learning test was repeated, and a second blood sample was taken. The clinical evaluation, the verbal learning test and the blood drawing were repeated a third time 3 weeks after the second assessment. The amount of anticholinergic activity in the blood samples was measured by a competitive radioligand binding assay and expressed in atropine equivalents. Analyses of variance indicated that there were no significant differences at the predrug Assessment 1 between patients subsequently assigned to the fluoxetine group compared with those assigned to the amitriptyline group. At Assessments 2 and 3, the fluoxetine and the amitriptyline groups showed equal clinical improvement but patients receiving amitriptyline did not perform as well on the verbal learning task. Serum anticholinergic activity at Assessments 2 and 3 was considerably higher in the amitriptyline group. This supports the hypothesis that blockade of muscarinic receptors impairs working memory formation. Equally effective antidepressant drugs with little or no anticholinergic action, such as fluoxetine, may be preferable in patients with pre-existing mild cognitive impairment or in patients where a slight reduction in cognitive performance is not acceptable.

A comparison of fluoxetine and amitriptyline in the treatment of major depression.

Fluoxetine, a new serotonin uptake blocking antidepressant, was compared with amitriptyline in a double-blind study. Patients were diagnosed as having major depression, according to DSM-III criteria, when interviewed with the Diagnostic Interview Schedule. There was significant improvement in patient and observer ratings of depression in both groups, with no difference between groups. Recent memory improved significantly in the fluoxetine group but not in the amitriptyline group. Numbers of patients reporting side-effects were similar but the profiles of side-effects were different, with more patients on amitriptyline reporting anticholinergic and intolerable side-effects.