Exploring the genetic overlap between substance use disorder and educational attainment.

Area of Science:

• Psychiatric Genetics
• Behavioral Genetics
• Genomics

Background:

• Substance use disorder (SUD) is a complex polygenic psychiatric condition.
• Higher educational attainment (EA) is associated with a reduced risk for SUD.
• Understanding the genetic relationship between EA and SUD is crucial for developing targeted interventions.

Purpose of the Study:

• To investigate the genetic overlap between EA and SUD using a general addiction risk factor.
• To examine the polygenic contribution of addiction and EA to SUD diagnosis and clinical heterogeneity.
• To dissect the genetic liability of addiction in relation to EA and its overlap with other traits.

Main Methods:

• Utilized GWAS summary statistics for EA (n=766,345) and addiction (n=647,703).
• Applied a multistep approach including genetic correlation analysis and polygenic risk score analysis in an independent clinical sample (1427 SUD cases, 2309 controls).
• Dissected genetic liability of addiction based on its relationship with EA and assessed overlap with SUD-related traits and other disorders.

Main Results:

• Confirmed a significant negative genetic correlation between addiction and EA (r_g = -0.33, P < 1.14e-57).
• The genetic liability of addiction discordant with EA showed the strongest effect on SUD (OR = 1.66, P < 2.01e-40).
• This discordant variation was associated with worse sociodemographic, health, and SUD-related outcomes.

Conclusions:

• Provided new evidence for a shared genetic basis between addiction and EA.
• Clarified the polygenic effects of addiction on SUD diagnosis and outcomes by separating genetic liability based on EA.
• Offered novel insights into shared genetic signatures between addiction, EA, and comorbid traits.