Abstract
Objective: Is it possible to predict the antidepressant treatment response in patients with major depressive disorder? For the antidepressant treatment, the common belief is to wait 6 weeks for deciding its effectiveness. It seem to be crucial to shorten this period for the patients with depressive symptoms in order to make earlier interventions. The aim of this survey is to find the association between early symptomatic improvement and the clinical response to antidepressant treatment in depression.
Method: Eighty-seven participants who met the DSM-IV criteria for major depressive disorder in both inpatient and outpatient clinics were included in this study. During the initial, second, fourth and sixth weeks of the treatment Hamilton Depression Scale (HDS) were applied; the %50 reduction of the HDS score achieved in the sixth week was defined as treatment response. The relation between the degree of decrease in second and fourth week HDS scores with the response in the sixth week were investigated.
Results: At the end of sixth week, 73 (%83.9) of 87 patients responded to their treatment, whereas 14 (%16.1) of them did not. The correlation between the degree of reductions in HDS scores at the second and sixth weeks was not statistically significant, whereas statistically significant results were found between the decreases in HDS scores at fourth and sixth weeks.
Discussion: The findings of this study suggest that the patients who did not respond to their treatment in the early stage did not show satisfactory response to their treatment afterwards. Based on the results, increasing the doses and switching the drugs may well be considered even in the early stages of the disorder.

Key words: depression, antidepressant medication, early improvement