Environmental risk factors and their impact on the age of onset of schizophrenia: Comparing familial to non-familial schizophrenia

Nord J Psychiatry. 2012 Apr;66(2):107-14. doi: 10.3109/08039488.2011.605171. Epub 2011 Aug 31.


Background and aims: Several risk factors for schizophrenia have yet been identified. The aim of our study was to investigate how certain childhood and adolescent risk factors predict the age of onset of psychosis in patients with and without a familial component (i.e. a relative with schizophrenia or schizoaffective disorder).

Methods: Aside from the age of onset of psychosis, we examined the risk factors for schizophrenia including obstetric complications, birth during winter or spring, behavioral deviances or delayed motor and speech development, exposure to adverse life events and exposure to substance use within a group of 100 patients (45 female, 55 male) with a mean age (± standard deviation) of 35.15 ± 13.21.

Results: Birth complications and cannabis abuse are predictors for an earlier onset of schizophrenia in patients with non-familial schizophrenia. No environmental risk factors for an earlier age of onset in familial schizophrenia have been identified.

Conclusions: Certain environmental risk factors for schizophrenia seem to have an impact on the age of onset of psychosis in non-familial schizophrenia, they do not seem to have an impact on familial schizophrenia.

MeSH terms

  • Adult
  • Age of Onset
  • Case-Control Studies
  • Developmental Disabilities
  • Environment
  • Female
  • Humans
  • Male
  • Marijuana Abuse / epidemiology
  • Obstetric Labor Complications
  • Pregnancy
  • Psychotic Disorders / epidemiology*
  • Psychotic Disorders / genetics
  • Risk Factors
  • Schizophrenia / epidemiology*
  • Schizophrenia / genetics*
  • Seasons
  • Substance-Related Disorders / epidemiology
  • Young Adult