Morning and evening plasma melatonin and dexamethasone suppression test in patients with nonseasonal major depressive disorder from northern Greece (latitude 40-41.5 degrees ).

INTRODUCTION: The present study aimed to search for correlations between melatonin (MT) levels and the dexamethasone suppression test (DST) and clinical variables. METHODS: Fifty depressed patients aged 21-60 years took part in the study. The Schedules for Clinical Assessment in Neuropsychiatry, version 2.0, and the International Personality Disorders Examination were used for diagnosis. Psychometric assessment included the Hamilton Depression Rating Scale, the Hamilton Anxiety Scale, the General Assessment of Funtioning Scale, the Newcastle scales and the Diagnostic Melancholia Scale. The DST and 9.00 and 23.00 h MT values were assessed. Statistical analysis included Student's t test, Pearson product moment correlation coefficient and forward stepwise multiple linear regression analysis. RESULTS: Melancholic patients had lower 23.00 h MT values in comparison to the rest of the patients and the atypical and 'undifferentiated' patients. CONCLUSION: The current study shows that low MT values were closely related to melancholic depression. Distinct quality of mood, psychomotor agitation or retardation and anorexia or weight loss seemed to be responsible for this relationship.