The process of becoming addicted to a substance requires a cascade of complicated neurological modifications that reshape brain circuitry. During the last 50 years, thousands of researchers have put in countless hours of work into understanding the nuances of addiction. While their work has helped us to better understand how these substances wreak havoc on the brain, there is still much we do not know. Today we are going to break down the neuroscience behind addiction.
Like most bodily responses, genetics and environment play a large role in our experience. It is estimated that 40-60% of addiction vulnerability is genetic, while the rest is environmental. Genetically speaking, your vulnerability is dependent on your body’s ability to metabolize the substance, sensitivity to the effects of the substance, and sensitivity to environmental stressors. Additionally, mental health issues and developmental disorders can increase the risk of addiction. It is believed that this comorbidity occurs for two reasons. First, it is likely that the alternative wiring patterns in brain networks found in many mental disorders and sensitivity toward addiction are likely mediated by similar genetic variations. Second, the additional stressors and stigma associated with mental illness can lead to substance use as a means of coping (National Institute on Drug Abuse, 2021; Volkow & Li, 2005).
Most addictive substances work through repeated activation of dopaminergic circuits within the midbrain, nucleus accumbens, and ventral tegmental area. This activation signals to your brain that the substance and environment surrounding the substance use is incredibly rewarding (Kosten & George, 2002). In fact, the environmental experiences become so heavily coded into your brain’s attributions of the substance that intense cravings and subsequent relapses can be triggered years and years later when given similar environmental cues (Hyman & Malenka, 2001).