Reduction of night/day difference in melatonin blood levels as a possible disease-related index in schizophrenia.

OBJECTIVE: Aim of this study was to verify if a simple index as night-day plasma MLT level variation is able to confirm the existing data on circadian melatonin alterations in schizophrenia and if a relationship to disease itself instead of the actual clinical state can be suggested.

SETTING AND DESIGN: Ten consecutively admitted male schizophrenic inpatients were examined.

METHODS: The blood samples for melatonin were collected at 3.00 a.m. and 15.00 p.m. and consequently calculated the values of Delta () (MLT h.3.00- MLT h.15.00). We divided the sample into two subgroups: < 30 pg/ml and > 30 pg/ml taking 30 pg/ml as an arbitrary value, based on literature data, that should indicate a physiologically correct value of.

RESULTS: The 70% of the sample was under the 30 pg/ml value of (13.61 +/- 4.0) or was lacking of the characteristic circadian pattern of MLT secretion, whilst the 30% of the sample was over the 30 pg/ml value of (83.60 +/- 16.34) or was in presence of the characteristic circadian pattern of MLT secretion (p=.0001). No correlation was found between values and the scale and subscales scores for the assessment of psychopathology.

MAIN FINDINGS: The data confirm the lack of the characteristic circadian pattern of MLT secretion in schizophrenics.

CONCLUSION: The absence of significant correlation between night / day melatonin level differences and actual psychopathology variables should indicate that the suppression of is mostly related to the disease and independent from the clinical state. A neuroleptic-treatment effect cannot be excluded so far.