A common genetic network underlies substance use disorders and disruptive or externalizing disorders

Area of Science:

• Neuroscience
• Genetics
• Psychiatry

Background:

• Attention deficit/hyperactivity disorder (ADHD), externalizing disorders, and substance-use disorder (SUD) are frequently comorbid.
• Shared genetic factors and biological mechanisms are suspected but not fully elucidated.

Purpose of the Study:

• To investigate the shared genetic basis and biological mechanisms underlying ADHD, externalizing disorders, and SUD.
• To explore the role of genetic interactions (epistasis) in phenotype severity and treatment response.
• To identify enriched biological pathways associated with these interconnected disorders using network analysis.

Main Methods:

• Review of existing literature and internal group data spanning two decades.
• Analysis of extended pedigrees showing segregation of ADHD, externalizing symptoms, and SUD.
• Formal network analysis of replicated genes associated with ADHD, disruptive behaviors, and SUD.

Main Results:

• Evidence supports a common biological basis, shared physiopathological mechanisms, and genetic factors for ADHD, externalizing disorders, and SUD.
• Genetic variants in different genes, and their non-linear interactions (epistasis), are associated with phenotype severity, outcome, and treatment response.
• Network analysis identified overrepresented pathways in axon guidance, synaptic transmission regulation, and nerve impulse transmission.

Conclusions:

• Compiled evidence points to complex genotype networks underlying the shared phenotype of SUD and externalizing disorders.
• These findings highlight the interconnectedness of these conditions at a genetic and biological level.
• Understanding these networks may inform future therapeutic strategies.