Association Between Substance Use Disorder and Polygenic Liability to Schizophrenia

Biol Psychiatry. 2017 Nov 15;82(10):709-715. doi: 10.1016/j.biopsych.2017.04.020. Epub 2017 Jun 6.


Background: There are high levels of comorbidity between schizophrenia and substance use disorder, but little is known about the genetic etiology of this comorbidity.

Methods: We tested the hypothesis that shared genetic liability contributes to the high rates of comorbidity between schizophrenia and substance use disorder. To do this, polygenic risk scores for schizophrenia derived from a large meta-analysis by the Psychiatric Genomics Consortium were computed in three substance use disorder datasets: the Collaborative Genetic Study of Nicotine Dependence (ascertained for tobacco use disorder; n = 918 cases; 988 control subjects), the Collaborative Study on the Genetics of Alcoholism (ascertained for alcohol use disorder; n = 643 cases; 384 control subjects), and the Family Study of Cocaine Dependence (ascertained for cocaine use disorder; n = 210 cases; 317 control subjects). Phenotypes were harmonized across the three datasets and standardized analyses were performed. Genome-wide genotypes were imputed to the 1000 Genomes reference panel.

Results: In each individual dataset and in the mega-analysis, strong associations were observed between any substance use disorder diagnosis and the polygenic risk score for schizophrenia (mega-analysis pseudo-R2 range 0.8-3.7%; minimum p = 4 × 10-23).

Conclusions: These results suggest that comorbidity between schizophrenia and substance use disorder is partially attributable to shared polygenic liability. This shared liability is most consistent with a general risk for substance use disorder rather than specific risks for individual substance use disorders and adds to increasing evidence of a blurred boundary between schizophrenia and substance use disorder.

Keywords: Genetics; Polygenic risk score; Schizophrenia; Substance dependence; Substance use disorder.

MeSH terms

  • Adult
  • Case-Control Studies
  • Comorbidity
  • Female
  • Genetic Predisposition to Disease / genetics*
  • Genome-Wide Association Study*
  • Genotype
  • Humans
  • Male
  • Meta-Analysis as Topic
  • Middle Aged
  • Multifactorial Inheritance / genetics*
  • Phenotype
  • Polymorphism, Single Nucleotide / genetics
  • Risk Factors
  • Schizophrenia / genetics*
  • Substance-Related Disorders / genetics*
  • Young Adult