The effect of antidepressants on serum melatonin levels in endogenous depression

1. To assess the serum melatonin levels in patients suffering from endogenous depression and the effect of pharmacological therapy. 2. To establish possible correlation between the height from the mean sea levels and the patients suffering from endogenous depression.

Forty patients, 18 males and 22 females, suffering from endogenous depression (according to DSM IV criteria), aged 48.3 +/- 12.32 years were evaluated and serum melatonin level was assayed between 9-10 am. They were not on any drugs/medication, which was likely to alter serum melatonin level for one month prior to study. The serum melatonin levels were assessed at 0, 3, 6 and 12 months while they were continued to be treated. It also included 30 controls of the matched age and sex and satisfying the inclusion criteria. The possible correlation was also studied between the serum levels and the height from the mean sea level at which the patients reside.

The two groups were comparable at the beginning of the study. The serum melatonin levels started falling from three months onwards (from 9.99 +/- 3.59 pg/nl to 8.49 +/- 3.16 pg/nl; p < 0.05). However, the decline was maximum between 3-6 months (from 8.49 +/- 3.16 to 5.589 +/- 1.96; p<0.05). The serum levels became stationary beyond six months. Highest melatonin levels were observed in patients residing at an altitude of 6001-8000 metres (14.32 +/- 2.68 pg/ml; p < 0.05) followed by 4,001-6,000 meters (11.137 +/- 2.62 pg/ml; p < 0.05). However, the levels were almost stationary below 4,000 metres (p = 0.05).

1. Higher serum melafonin values were observed in patients suffering from endogenous depression. 2. Morning serum melatonin values decreased with pharmacological therapies. 3. Patients living at higher altitudes had higher serum values for the hormone.