Comparison of the Effects of Antidepressants with Different Mechanisms of Action on Efficacy, Cognitive Functions and Side Effects

Objective: The aim of this study was to compare the effects of the agomelatine and selective serotonin reuptake inhibitors (SSRIs) on symptoms of depression, cognitive functions, impulsiveness, suicidal tendency, sleep pattern and side effects. Method: This study enrolled patients with depression started on SSRIs (n=30) or agomelatine (n=30) on an outpatient basis. All patients were evaluated with SCID-I and the Sociodemographic Questionnaire on the first day of the treatment. In order to assess the side effects of the treatments, the patients were ass ssed at the first and the fourth weeks with Hamilton Depression Scale (HAM-D), the Suicide Probability Scale (SPS), the UPSS Impulsive Behaviour Scale, the Epworth Sleepiness Scale (ESS), the UKU Side Effect Rating Scale, and the Stroop Test and the Trail Making Test for cognitive functions. Results: Patients on SSRIs showed better treatment response and remission rates at the end of the first month. Improvement in cognitive functions correlated with the decrease in depressive symptoms, but no difference was observed between the groups with respect to the improvement of the cognitive functions. SSRIs caused more autonomic and sexual side effects compared to agomelatine. Differences were not observed between the effects of the two medications on impulsivity, sleep pattern and suicidal tendency. Conclusion: In conclusion, treatment with SSRIs was significantly more associated with improvement in the clinical symptoms. Sexual side effects were more prevalent with SSRIs, but the effect on cognitive functions did not differ from agomelatine Despite the distinct, promising mechanism of action, agomelatine was not as effective as the SSRIs for the treatment of depression.