Winter/summer seasonal changes in malondialdehyde formation as a source of variance in oxidative stress schizophrenia research.

BACKGROUND: Malondialdehyde (MDA), an oxidative stress biological marker, is one of the most frequently used markers of lipid peroxidation in schizophrenia research. Data regarding MDA levels in schizophrenia are controversial. Our aim is to study the existence of winter/summer seasonal changes in serum MDA levels in schizophrenic patients.
METHODS: Twenty-three clinically stable treated chronic paranoid schizophrenic outpatients were studied in summer and winter. Blood was sampled between 08:30 and 09:00 h. Serum MDA was determined by the thiobarbituric acid reactive substances technique. The clinical state was assessed by means of the Clinical Global Impression (CGI) scale.
RESULTS: Mean serum MDA levels were significantly higher in summer than winter (2.49+/-0.25 vs. 1.86+/-0.11 nmol/ml, P<0.03). Summer MDA was increased by a 33.9% compared to winter MDA. Age, gender, smoking status, body mass index, psychopharmacological treatment, illness duration, age of illness onset and CGI did not affect significantly MDA levels.
CONCLUSION: Our results show that serum MDA presents a winter/summer rhythm of formation, with higher levels in summer than winter. It is strongly advisable to take into account the summer/winter variation in MDA levels when researching into this field.