Rationale: The novel antidepressant agomelatine acts as a melatonergic (MT(1) and MT(2)) receptor agonist and as a serotonin-2C receptor antagonist. Previous studies showed that agomelatine is able to restore disrupted circadian rhythms, which were implicated in the pathophysiology of seasonal affective disorder (SAD).
Objectives: The aim of this study was to investigate the efficacy and tolerability of agomelatine in the treatment of SAD.
Materials and methods: Thirty-seven acutely depressed SAD patients were included in an open study with agomelatine (25 mg/day in the evening) over 14 weeks. Efficacy assessments included the Structured Interview Guide for the Hamilton Depression Rating Scale (SAD version; SIGH-SAD), the Clinical Global Impression of Severity (CGI-S) and Improvement (CGI-I), the Circscreen, a self-rating scale for the assessment of sleep and circadian rhythm disorders, and the Hypomania Scale.
Results: Agomelatine led to a progressive and statistically significant decrease of SIGH-SAD, CGI-S, and CGI-I scores from week 2 onward (p < 0.001). Furthermore, scores on the Circscreen improved significantly during the study (p < 0.001). Treatment with agomelatine over 14 weeks yielded a response rate of 75.7% (SIGH-SAD <50% of baseline value) and a remission rate (SIGH-SAD <8) of 70.3% in the intention to treat sample. Scores on the Hypomania Scale were consistently low during the study. Agomelatine showed good overall tolerability: throughout the study only one adverse event (mild fatigue) was related to the study drug.
Conclusions: The results of this study suggest that seasonal depression may be effectively and safely treated with agomelatine.