title: Winter/summer seasonal changes in malondialdehyde formation as a source of variance in oxidative stress schizophrenia research.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Internal Medicine, Dermatology and Psychiatry, La Laguna University Medical School, Tenerife, Spain. amorera@ull.es
authors.forename: Armando L
authors.initials: AL
authors.lastname: Morera
authors.forename: Aintzane
authors.initials: A
authors.lastname: Intxausti
authors.forename: Pedro
authors.initials: P
authors.lastname: Abreu-Gonzalez
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002908:Chronic Disease; D005260:Female; D006801:Humans; D015227:Lipid Peroxidation / Q000502:physiology; D008297:Male; D008315:Malondialdehyde / Q000097:blood*; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology*; D010507:Periodicity; D011569:Psychiatric Status Rating Scales; D012563:Schizophrenia, Paranoid / Q000175:diagnosis / Q000503:physiopathology*; D012621:Seasons; D055815:Young Adult
chemical_list: D008315:Malondialdehyde