Substance Use Disorders

Key Facts

• Substance use disorders affect over 48 million Americans and remain one of the nation’s leading public health challenges, with overdose the top cause of death for adults aged 18-44.

• Addiction (the most severe form of a substance use disorder) is a chronic brain disease that alters the brain’s reward and control systems. Recovery is possible as brain function can heal over time with treatment and abstinence.

• The risk of developing an SUD stems from a mix of genetic, individual, family, community, and societal factors, while strong protective factors—like family support, positive peer connections, and healthy environments—build resilience.

• Early screening and intervention prevent escalation to addiction and improve long-term outcomes through timely care and individualized treatment planning.

• Evidence-based treatments combining medications, behavioral therapies, and recovery supports reduce substance use, overdose deaths, and improve overall health and quality of life.

Overview

Substance use disorders (SUD) remain among the most significant public health challenges, affecting millions of individuals, families, and communities worldwide. SUDs are a medical condition that affects the brain and changes behavior. It is characterized by the compulsive use of alcohol or drugs despite harmful consequences, such as loss of a job, arrest, health complications, or other significant negative outcomes (Volkow & Blanco, 2023).

In the United States, over 48 million people aged 12 and older—about 1 in 6 people—met the criteria for a SUD in 2024 (SAMHSA, 2025). Additionally, more than 80,800 Americans died of a drug overdose in 2024 (Ahmad et al., 2025). While data shows a national decline in recent years, overdose remains the leading cause of death among people 18-44 (CDC, 2025). 

Despite these alarming national impacts, SUDs are preventable, treatable, and people do recover. In fact, 23.5 million people considered themselves to be in recovery, showing that SUDs are treatable and individuals can recover (SAMHSA, 2025).

Addiction and the Brain

Addiction is the most severe form of an SUD and causes fundamental changes in how the brain functions, particularly in the reward, motivation, and memory systems (Volkow & Blanco, 2023). 

When drugs are used, they flood the reward pathway—particularly the nucleus accumbens and prefrontal cortex—with dopamine. This overstimulation produces intense euphoria, reinforcing the behavior. Over time, these changes reduce sensitivity to natural rewards and impair executive control, making it harder for people to quit even when they want to.

Science also shows that the brain can recover and heal. It takes time, treatment, and abstinence. Research using brain imaging shows that within months of abstinence, brain regions impacted by addiction—involved in judgment, decision-making, and emotional regulation—begin to regain normal functioning (NIDA, 2020).

Types of Substance Use Disorders

Patients are diagnosed with a specific type of SUD based on the primary substance that they use/misuse, such as alcohol, tobacco/nicotine, opioids (e.g., heroin, fentanyl, or prescription pain relievers), marijuana, stimulants (e.g., cocaine or methamphetamine), hallucinogens (e.g., PCP or LSD), and sedatives (e.g., sleeping pills or benzodiazepines).

However, many patients diagnosed with SUD use more than one kind of substance—this is known as a polysubstance use disorder.

Signs, Symptoms, and Diagnosis

SUDs are diagnosed using clinical guidelines from the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), a standardized manual based on decades of research and developed by hundreds of mental health experts (APA, 2022). Determining symptoms and the severity level of the SUD helps clinicians develop the best treatment plan.

Categories of SUD Symptoms

The DSM-5 includes 11 criteria to determine different levels of severity based on four main categories: 1) impaired control; 2) social problems; 3) risky use, and 4) physical dependence.

Levels of Severity

SUD severity is determined by the number of symptoms that are present, with higher severity indicating the more intensive the level of treatment needed. Severity ranges from:

• Mild (2-3 symptoms)

• Moderate (4-5 symptoms)

• Severe (6 or more symptoms) – also known as having an addiction

Early Detection and Intervention

Intervening early can prevent SUDs from progressing to addiction and its associated health and social consequences. Screening and assessment are foundational steps in identifying severity and specific service needs. 

• Screening involves the use of brief, structured instruments to determine whether an individual currently has, or may be at risk of developing, an SUD. These tools help determine the need for a more comprehensive clinical evaluation and facilitate early referral to care. Many validated screening instruments can be administered efficiently in medical, behavioral health, or community settings and often require minimal specialized training.

• Comprehensive assessments are needed when screening results indicate elevated risk or probable SUD. This assessment is conducted by a trained healthcare professional who evaluates the severity of the disorder, identifies co-occurring mental or physical health conditions, and informs the development of an individualized treatment plan. It also determines the most appropriate level and setting to receive care (e.g., intensive outpatient, partial hospitalization, or residential treatment).

Evidence-based Treatment

Treating SUDs is most effective when it integrates medications, behavioral therapies, and recovery supports tailored to individuals’ needs. Decades of research show that these evidence-based approaches reduce substance use, overdose deaths, criminal justice involvement, and infectious disease transmission, while improving treatment engagement, retention, and overall health and social outcomes (NIDA, 2014).

Medications for Addiction Treatment (MAT)

Currently, there are FDA-approved medications to treat opioid use disorder, alcohol use disorder, and tobacco use disorder. MAT helps stabilize brain chemistry, reduce or block the euphoric effects, relieve cravings, and help patients engage in other aspects of treatment. 

Opioid Use Disorder Medications

• Methadone is a long-acting full opioid agonist that binds to the same receptors as heroin and other opioids, preventing withdrawal symptoms and reducing cravings without producing the same euphoric effects when taken as prescribed. It is administered daily under medical supervision in federally regulated opioid treatment programs (OTPs) and is available in tablet and liquid formulations.

• Buprenorphine is a partial opioid agonist that binds to the opioid receptors but to a much lesser degree than full agonists. This ceiling effect reduces the risk of misuse, respiratory depression, and overdose. Available in multiple formulations (sublingual tablets, films, and long-acting injectables), buprenorphine can be prescribed by physicians, nurse practitioners, or physician assistants in office-based settings. 

• Naltrexone is an antagonist medication that blocks opioids from binding to the receptors in the brain. The extended-release injectable provides up to 30 days of effects and should only be administered after 7-14 days of abstinence. Physicians, nurse practitioners, and physician assistants can prescribe and administer naltrexone without an additional license.

Alcohol Use Disorder Medications 

• Acamprosate has agonist and antagonist effects on different receptors in the body and works to restore balance between the brain’s systems disrupted by chronic alcohol use. It does not prevent withdrawal symptoms, but it can reduce the negative symptoms associated with the period immediately following alcohol withdrawal, such as insomnia, anxiety, restlessness, and depression. Acamprosate is dispensed as a tablet that is taken three times a day.

• Disulfiram is an oral medication taken daily to discourage alcohol consumption. Unlike other medications that act on brain receptors, disulfiram blocks enzymes in the body that break down alcohol. If alcohol is consumed by someone taking disulfiram, it can cause nausea, flushing, headache, palpitations, and vomiting. This reaction creates a strong aversive response by creating a strong negative association with alcohol and making drinking an undesirable experience. 

• Naltrexone is also approved for the treatment of alcohol use disorder. It works by reducing the euphoric effects of alcohol by blocking the receptors in the brain that are involved in the rewarding and reinforcement effects of drinking. Naltrexone does not relieve withdrawal symptoms but is effective in helping individuals maintain abstinence or reduce heavy drinking. It is available as a daily oral tablet or a monthly extended-release injectable. 

Tobacco Use Disorder Medications

• Nicotine Replacement Therapy (NRT) delivers controlled, low doses of nicotine through over-the-counter products (e.g., patches, gum, lozenges), as well as prescription inhalers and nasal sprays, to reduce cravings and lessen withdrawal symptoms after quitting smoking. NRT helps individuals transition away from smoking by gradually lowering nicotine intake. 

• Bupropion is a pill that is taken twice a day to help reduce nicotine cravings and withdrawal symptoms. It is a non-nicotine-based antagonist and can be used alone or in combination with NRT (e.g., patches, gums, etc.). Bupropion is also approved to treat depression.

• Varenicline is a partial nicotinic receptor agonist that reduces nicotine cravings and withdrawal symptoms while blocking the rewarding effects of smoking. It contains no nicotine and is taken orally twice daily, typically starting one week before the planned quit date with a gradual dose increase.

Behavioral Therapies

Behavioral therapies are a key component of SUD treatment. They focus on modifying the thoughts, emotions, and behaviors that contribute to substance use while helping individuals develop healthier coping strategies and life skills.

Evidence-based behavioral therapies include:

• Cognitive Behavioral Therapy (CBT) helps individuals identify and change destructive thought patterns that negatively influence emotions and behaviors. CBT addresses these maladaptive thought patterns by teaching practical coping strategies to manage cravings, reduce substance use, and prevent subsequent behaviors.

• Contingency Management (CM) uses positive reinforcement through various incentive methods to encourage behaviors that support recovery, such as abstinence, counseling attendance, and medication adherence. Incentives may include vouchers, gift cards, or social recognition. By activating the brain’s reward system, CM replaces the reinforcement once provided by substance use with healthier, prosocial rewards.

• 12-Step Facilitation Therapy helps individuals engage with mutual support programs such as Alcoholics Anonymous (AA) and Narcotics Anonymous (NA). It promotes acceptance of addiction as a chronic disease, emphasizes abstinence, and fosters connection with a supportive recovery community through shared experiences and accountability.

• Motivational Enhancement Therapy (MET) is a goal-oriented intervention that strengthens motivation and commitment to behavior change. It involves combining assessments, goal setting, and motivational interviewing. Through a series of focused sessions that combine assessments, goal setting, and motivational interviewing, MET helps individuals build confidence, resolve ambivalence, and develop a personalized plan for recovery from substance use.

• Therapeutic Communities (TC) are structured residential programs that promote abstinence, prosocial behavior, and personal and social responsibility through peer-driven supportive environments. Individuals actively participate in group living and activities within a community made up of peers, treatment staff, and individuals in recovery. TCs prepare individuals for reintegration into work, education, and community life, helping them sustain recovery and rebuild social and vocational functioning.

Recovery Support Programs

Recovery support programs play a vital role in sustaining long-term recovery from SUDs by providing ongoing social, emotional, and practical support beyond formal treatment. These programs reinforce the gains made during treatment, promote stability, and help individuals rebuild meaningful lives in the community. 

Specific types of recovery programs include: 

• Recovery Housing

• Peer Support Services

• Recovery Community Organizations

• Mutual Aid Support Groups (AA, NA)

• Activity-Based Recovery

• Recovery High Schools

• Collegiate Recovery

• Faith-Based

• Online Support

Learn more about recovery support programs. 

References

Ahmad, F. B., Cisewski, J. A., Rossen, L. M., & Sutton, P. (2025). Provisional drug overdose death counts. National Center for Health Statistics. Retrieved November 4, 2025, from www.cdc.gov/nchs/nvss/vsrr/drug-overdose-data.htm

American Psychiatric Association. (2022). Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR). https://psychiatryonline.org/doi/book/10.1176/appi.books.9780890425787

Centers for Disease Control and Prevention. (2025). CDC Reports Nearly 24% Decline in U.S. Drug Overdose Deaths. www.cdc.gov/media/releases/2025/2025-cdc-reports-decline-in-us-drug-overdose-deaths.html

National Institute on Drug Abuse. (2014). Principles of Drug Addiction Treatment: A Research-Based Guide (Third Edition). https://nida.nih.gov/sites/default/files/podat-3rdEd-508.pdf

National Institute on Drug Abuse. (2020). Drugs, Brains, and Behavior: The Science of Addiction. https://nida.nih.gov/research-topics/addiction-science/drugs-brain-behavior-science-of-addiction

Substance Abuse and Mental Health Services Administration. (2025). Key substance use and mental health indicators in the United States: Results from the 2024 National Survey on Drug Use and Health (HHS Publication No. PEP25-07-007, NSDUH Series H-60). Center for Behavioral Health Statistics and Quality, Substance Abuse and Mental Health Services Administration. https://www.samhsa.gov/data/data-we-collect/nsduh-national-survey-drug-use-and-health/national-releases/2024

Volkow, N. D., & Blanco, C. (2023). Substance use disorders: a comprehensive update of classification, epidemiology, neurobiology, clinical aspects, treatment and prevention. World psychiatry: official journal of the World Psychiatric Association (WPA), 22(2), 203–229. https://doi.org/10.1002/wps.21073