# Substance Use Disorders: From Adolescent Experimentation to Adult Addiction

## Introduction

Substance use disorders (SUDs) exist on a spectrum from experimentation in adolescence to chronic, relapsing addiction in adulthood. The med-peds physician encounters this continuum regularly and must be equipped to **screen, intervene, and treat** across ages. Understanding the neurodevelopmental vulnerability of the adolescent brain and the chronic disease model of addiction is essential.

## Epidemiology

**Adolescents**: 50% have tried an illicit substance by 12th grade; vaping and marijuana are the most common. **Young adults (18-25)**: Highest rates of binge drinking, marijuana use, and opioid misuse. **Adults**: Alcohol use disorder affects ~15 million Americans; opioid use disorder ~2 million. Adverse childhood experiences (ACEs) strongly correlate with later substance use disorders.

## Neuroscience of Addiction

### The Adolescent Brain
Prefrontal cortex (decision-making, impulse control) does not fully mature until age ~25. Reward circuitry (nucleus accumbens, dopamine pathways) is highly active in adolescence. This mismatch creates a **window of vulnerability** for substance use initiation. Early initiation of substance use is the strongest predictor of later addiction.

### Neurobiologic Model
**Binge/intoxication**: Dopamine surge in ventral tegmental area and nucleus accumbens. **Withdrawal/negative affect**: Decreased dopamine function, increased stress hormones. **Preoccupation/anticipation**: Prefrontal cortex dysregulation, craving.

![Diagram of the three-stage cycle of addiction](images/addiction-cycle.jpg)

## Screening

### Adolescents
**CRAFFT 2.1**: Validated 6-question screen for substance use in ages 12-21. Car, Relax, Alone, Forget, Friends, Trouble. Score 2+ suggests problematic use. **NIAAA Youth Alcohol Screening**: Age-specific questions about friends' drinking and personal drinking. Screen at every well-adolescent visit per AAP guidelines.

### Adults
**AUDIT-C**: 3-question alcohol screen (score 4+ men, 3+ women is positive) **DAST-10**: Drug Abuse Screening Test. **Single-question screen**: "How many times in the past year have you used an illegal drug or a prescription medication for nonmedical reasons?" (any positive response warrants further assessment) SBIRT model: **Screening, Brief Intervention, Referral to Treatment**.

## Specific Substances

### Alcohol
Binge drinking: 5+ drinks (males) or 4+ drinks (females) on one occasion. Alcohol use disorder: DSM-5 criteria (2+ of 11 criteria in 12-month period) Medical complications: Liver disease, pancreatitis, cardiomyopathy, neuropathy, Wernicke-Korsakoff syndrome. **Treatment**: Naltrexone, acamprosate, disulfiram; CBT, motivational enhancement therapy, 12-step programs.

### Opioids
Prescription opioid misuse often precedes heroin or fentanyl use. Fentanyl contamination of illicit drugs dramatically increases overdose risk. **Medication-assisted treatment (MAT)**: Buprenorphine (X-waiver eliminated in 2023), methadone, naltrexone. **Naloxone**: Prescribe to all patients at risk of opioid overdose; educate families.

### Cannabis
Most commonly used illicit substance in adolescents. Adolescent use associated with impaired memory, reduced IQ, increased psychosis risk. Cannabis use disorder is real and undertreated. No FDA-approved pharmacotherapy; behavioral interventions are primary treatment.

### Nicotine/Vaping
E-cigarettes are the most commonly used nicotine product among youth. EVALI (E-cigarette or Vaping Product Use-Associated Lung Injury) risk. Nicotine replacement therapy, bupropion, and varenicline for cessation (limited adolescent data)

![Infographic on trends in adolescent substance use](images/adolescent-substance-trends.jpg)

## Brief Intervention and Motivational Interviewing

Express empathy; avoid judgment; Develop discrepancy between current behavior and personal goals; Roll with resistance; Support self-efficacy; Effective in both adolescent and adult populations; Even a single brief intervention can reduce risky drinking by 20-30%.

## Pharmacotherapy Summary

| Substance | Medications | Notes |
|---|---|---|
| Alcohol | Naltrexone, acamprosate, disulfiram | Naltrexone also reduces craving in opioid use disorder |
| Opioids | Buprenorphine, methadone, naltrexone (IM) | MAT reduces mortality by 50%+ |
| Nicotine | NRT, bupropion, varenicline | Combination NRT most effective |
| Cannabis | None FDA-approved | CBT + motivational enhancement |
| Stimulants | None FDA-approved | CBT, contingency management |

## Special Populations

**Pregnant patients**: Opioid use disorder treatment with buprenorphine or methadone; neonatal opioid withdrawal syndrome (NOWS) management. **Adolescents**: Family-based therapy is critical; confidentiality considerations. **Patients with co-occurring mental health disorders**: Integrated dual-diagnosis treatment.

![Flowchart showing SBIRT model for substance use screening](images/sbirt-model.jpg)

## Clinical Pearls

Screen every adolescent for substance use at every well visit using CRAFFT; normalize the conversation. The adolescent brain is uniquely vulnerable to addiction; early intervention can prevent decades of disease. Medication-assisted treatment for opioid use disorder is first-line and life-saving; all med-peds physicians should be comfortable prescribing buprenorphine. Naloxone should be co-prescribed with any opioid prescription and offered to patients with SUD and their families. Addiction is a chronic, relapsing brain disease; treat it with the same longitudinal, nonjudgmental approach used for diabetes or hypertension.

## References

1. Levy SJ, Williams JF, Committee on Substance Use and Prevention. Substance use screening, brief intervention, and referral to treatment. *Pediatrics*. 2016;138(1):e20161211.
2. Volkow ND, Koob GF, McLellan AT. Neurobiologic advances from the brain disease model of addiction. *N Engl J Med*. 2016;374(4):363-371.
3. Jonas DE, Amick HR, Feltner C, et al. Pharmacotherapy for adults with alcohol use disorders in outpatient settings: A systematic review and meta-analysis. *JAMA*. 2014;311(18):1889-1900.
4. Hadland SE, Bagley SM, Rodean J, et al. Receipt of timely addiction treatment and association of early medication treatment with retention in care among youths with opioid use disorder. *JAMA Pediatr*. 2018;172(11):1029-1037.