Lecture Notes: Substance Use and Addiction

Introduction

• High prevalence of substance use among teens:
  • 70% have tried alcohol by high school graduation.
  • 50% have tried illegal drugs.
  • Close to 50% have smoked or vaped nicotine.
  • 1 in 5 have used prescriptions off-label.

Early Exposure and Risk Factors

• Early exposure is a primary factor in developing substance use disorders.
• Majority with substance use disorders began using before 18.
• Starting alcohol use by age 14 increases the likelihood of developing alcohol problems by seven times compared to waiting until 21.

Reasons for Adolescent Risk-Taking

• Evolutionary benefits:
  • Risk-taking and novelty-seeking have historically benefited populations.
  • Helps in identity development.
• Brain development:
  • Reward pathways develop faster than caution and impulse control.

Personal Story and Broader Context

• Personal experience with substance abuse:
  • Started drinking at 13, leading to homelessness and health issues.
  • Kicked out of multiple schools and contracted hepatitis C.
• Recovery led to pursuing a PhD in neuroscience.

Characteristics of Addiction

• Addiction is characterized by:
  • Craving and compulsive use.
  • Tolerance: Drugs become less effective over time.
  • Dependence: Feeling worse without the drugs.
• Risk factors:
  • Genetics account for about half of addiction risk.
  • Environmental factors: access, stress.
  • Developmental factors: adverse early experiences prime for addiction.

Model of Addiction

• Homeostatic feeling states:
  • Baseline feeling states maintained by the nervous system.
  • Good or bad events temporarily alter this state.
• Effect of substances:
  • Substances can temporarily improve mood.
  • Overuse leads to tolerance and adaptation, with feelings of normalcy only with drug use.

Specific Example: Marijuana

• THC and the Brain:
  • THC activates the endocannabinoid system.
  • Affects areas related to learning, memory, motivation, and reward.
• Effects of Regular Use:
  • Brain adapts to constant THC, reducing motivation and interest without it.
  • Chronic use during development leads to lasting changes in brain processing.

Conclusion

• Substance abuse is the leading cause of death for people under 50.
• Regular use of addictive substances causes opposite desired feeling states.
• Personal anecdote: initial enjoyment of marijuana leading to eventual lack of interest in life.

Key Takeaways

• Early exposure and risk-taking tendencies in adolescence are critical in substance use disorder development.
• Addiction involves complex interactions between genetic, environmental, and developmental factors.
• Understanding brain adaptations in response to drugs can provide insight into the nature of addiction.