WHY DO DRUG ABUSE AND MENTAL DISORDERS COMMONLY CO-OCCUR?
• Overlapping genetic vulnerabilities. Mounting evidence suggests that common genetic factors may predispose dual diagnosis individuals to both mental disorders and addiction, or to having a greater risk of the second co-occuring disorder once the first appears. • Overlapping environmental triggers. Stress, trauma (e.g., physical or sexual abuse), and early exposure to drugs are common factors that can lead to addiction and to mental illness, particularly in those with underlying genetic vulnerabilities. • Involvement of similar brain regions. Some areas of the brain are affected by both drug abuse and mental disorders. For example, brain circuits linked to reward processing as well as those implicated in the stress response are affected by abused substances and also show abnormalities in specific mental disorders. • Drug abuse and mental illness are developmental disorders. They often begin in adolescence or even childhood, periods when the brain is undergoing dramatic developmental c
