Day # 160: Introduction to Substance Use Disorders
- Marcus Hunt
- Feb 16
- 7 min read
Addiction and substance use disorders (SUDs) are complex, chronic conditions that impact both brain function and behavior. This post provides an overview of key concepts—from definitions and diagnostic criteria to clinical features and management strategies.
Today's Content Level: Beginner, Intermediate
Various terms have been used over the years to refer to drug abuse:
Substance use: The consumption of psychoactive substances. May or may not lead to pathological behavior.
Substance abuse: The use of any drug in a manner that deviates from approved social or medical patterns.
Substance use disorder (SUD): A problematic pattern of use leading to clinically significant impairment or distress. Chronic, relapsing disorder marked by compulsive use, loss of control, and continued use despite harmful consequences. Diagnosed based on DSM-5 criteria (see below).
Addiction: In many ways, addiction is synonymous with SUD, however it applies more broadly to include other addictive behaviors such as gambling, sex, stealing, or eating addictions. The term addict has taken on a negative connotation, overlooking the science that substance abuse is a medical condition.
Intoxication, Dependence, Tolerance, and Withdrawal:
Intoxication: The immediate, reversible, and often dose-related pharmacological impact of a substance. It influences one or more mental functions, including memory, orientation, mood, judgment, and behavioral and social functioning. Specific effects will vary based on the substance consumed (e.g., euphoria vs anxiety or paranoia, sedation vs increased energy and alertness, impaired judgment, disinhibition, altered motor coordination, etc.).
Dependence: Chronic substance use leads to physiological and psychological changes in reward pathways. Physiological dependence → adaptations that lead to tolerance and withdrawal (see below). Psychological or behavioral dependence → emotional and cognitive preoccupation with substance use such as cravings or compulsive behaviors.
Tolerance: A need for increased amounts of a substance to achieve the desired effect or diminished effect if using the same amount of the substance.
Withdrawal: The development of a substance-specific syndrome due to the cessation (or reduction) of substance use that has been heavy and prolonged.
Diagnostic Criteria and Symptoms of SUD 3, 4
SUDs are characterized by a problematic pattern of substance use that leads to impairment or distress manifested by ≥ 2 of the following within a 12-month period. Note that these criteria are the same regardless of the substance.
Using substance more than originally intended (larger amounts or over a longer period).
Loss of control; persistent desire or unsuccessful efforts to cut down.
Significant time spent in obtaining, using, or recovering from substance.
Craving: Intense desire or urge to use the substance.
Recurrent use leading to failure in fulfilling major obligations.
Continued use despite social or interpersonal problems due to the substance use.
Giving up or reducing important social, occupational, or recreational activities.
Use in physically hazardous situations (e.g, driving a car).
Continued use despite knowing that it causes or exacerbates physical or psychological problems (e.g., depression, anger, liver problems).
Tolerance
Withdrawal
Severity Specifiers:
Mild: 2–3 criteria met.
Moderate: 4–5 criteria met.
Severe: ≥ 6 criteria met.
Other symptoms of SUD:
Psychiatric Symptoms
There may be compulsive use or ritualized behaviors surrounding the substance use.
Mood Dysregulation: Irritability, anxiety, or depressive symptoms linked to substance effects or withdrawal. Mood symptoms are common among people with substance disorders. Psychotic symptoms may occur with some substances. It can be challenging to determine whether psychiatric symptoms are primary or substance-induced.
Emotional Reliance: Using substances to manage emotions or stress.
Other Physical Symptoms
Withdrawal Symptoms: Characterized by a range of physiological signs and symptoms (e.g., tremors, sweating, nausea, seizures) in addition to psychological changes, such as disturbances in thinking and behavior. Withdrawal symptoms of a drug are usually opposite of its intoxication effects. For example, alcohol is sedating, but alcohol withdrawal can → brain excitation, anxiety, and seizures. Severe withdrawal from certain substances (e.g., alcohol, benzodiazepines, barbiturates) can be life-threatening.
Organ-Specific Effects: Examples include liver damage with alcohol use or respiratory compromise with tobacco smoking.
SUDs are a major public health issue, leading to substantial morbidity, mortality, and economic burden. It affects a significant portion of the population, with variations across age, gender, and socioeconomic groups. Genetics, environmental influences, mental health comorbidities, and early exposure contribute to vulnerability.
Prevalence: Data from the 2023 United States National Survey on Drug Use and Health (NSDUH) → 16.7% of Americans battled a SUD in the past year. Nicotine and alcohol remains the most common substances abused → 10.2% of Americans had an Alcohol Use Disorder (AUD) in the past year. There are rising trends noted in cannabis, opioid, and stimulant use disorders.
Gender and Age: For most age groups, men have higher rates of use or dependence of illicit drugs and alcohol than do women. However, women are just as likely as men to develop a substance use disorder. Adolescents and young adults are more at risk compared to other age groups.
Genetics and Biology: Genetics, including the impact of one’s environment on gene expression, account for about 40% - 60% of a person’s risk of addiction. Involved brain regions include specific reward areas such as the ventral tegmental area, locus coeruleus, nucleus accumbens, amygdala, and anterior cingulate. More on these brain areas in later lessons. Also, individuals with comorbid mental health disorders are more at risk for drug use and addiction than other populations.
Environmental Influences: Factors that may increase a person’s risk of addiction include a chaotic home environment, abuse or other traumatic experiences, parent’s drug use and attitude toward drugs, peer influences, community attitudes toward drugs, and poor academic achievement. While drug availability, social acceptability, and peer pressure may largely drive initial experimentation with a drug, factors like personality and individual biology likely play a more significant role in how a person perceives the drug's effects and the extent to which repeated use alters the central nervous system.
Learning and Conditioning: Drug use reinforces itself by alleviating aversive states such as pain, anxiety, or depression. Each use of the drug leads to rapid positive reinforcement through euphoria, relief from disturbed affects, alleviation of withdrawal symptoms, or a combination of these effects.
Management of SUDs 8
A thorough assessment is the foundation of effective management. Effective treatment requires a combination of medical, psychological, and social interventions. A multi-disciplinary team—often including psychiatrists, primary care providers, therapists, social workers, and peer support specialists collaborates to address all aspects of the SUD.
Assessment: History → detailed substance use history (onset, frequency, quantity, route, last use), prior treatment attempts, withdrawal symptoms, impact on daily functioning, and co-occurring psychiatric or medical conditions. Keep in mind that it is common for people to abuse several substances at once. Always be on the lookout for multiple substance use. Screening Questionnaires → tools such as the AUDIT (Alcohol Use Disorders Identification Test), DAST (Drug Abuse Screening Test), and CAGE questionnaire can aid in detection. Physical Exam → assess for signs of intoxication, withdrawal, and long-term complications. Labs → depending on the suspected substance, relevant tests may include urine drug screens, liver function tests (LFTs), CBC, CMP, HIV/HCV screening, and cardiac evaluation (e.g., ECG).
Psychosocial Interventions: Individual and/or group therapy should be part of every SUD treatment approach. Behavioral Therapies → Cognitive Behavioral Therapy (CBT), Motivational Interviewing (MI), and Contingency Management (CM) are evidence-based approaches that help modify thoughts and behaviors related to substance use. CBT helps modify dysfunctional thinking and behaviors, MI enhances patient motivation to change, and CM uses incentives to reinforce abstinence. Peer Support & 12-Step Programs → Alcoholics Anonymous (AA), Narcotics Anonymous (NA), and SMART Recovery provide social support and structure and should be encouraged. Family & Social Support → involving family when appropriate can improve outcomes, especially through interventions like Community Reinforcement and Family Training (CRAFT). Resources such as Al-Anon can be provided to support family members of patients with AUD).
Medication-Assisted Treatment (MAT): MAT is a key component for certain substance use disorders, improving retention in treatment and reducing relapse rates. Specific medications are discussed in detail in individual lessons.
Treat Comorbidities: Other psychiatric conditions frequently co-occur with substance use disorders. Integrated treatment is crucial. Also, chronic conditions cause by drug use such as hepatitis C, HIV, liver disease, and cardiovascular disease require concurrent management.
Medically Assisted Withdrawal: Determining the need for medically supervised withdrawal (detoxification) depends on the substance, severity of dependence, and medical risk factors. This will be discussed in detail in individual lessons.
Treatment Programs: Choosing the right level of care depends on substance use severity, comorbid conditions, and prior treatment history. Outpatient Treatment → weekly or biweekly therapy, often with medication management. Suitable for mild to moderate cases with strong support systems. Intensive Outpatient Program (IOP) → typically involves 3-5 sessions per week, providing more structure while allowing patients to live at home. Partial Hospitalization Program (PHP) → more intensive than IOP, often requiring daily attendance for structured therapy, but without 24-hour supervision. Residential Treatment Programs (RTP) → also known as "rehab." 24/7 structured care, beneficial for severe cases, polysubstance use, or individuals with unstable home environments. Most programs fall within a 30-90 day timeframe.
Conclusion
•SUDs involve a complex interplay of genetics and environmental influences that lead to destructive behaviors and psychiatric and physical symptoms. Effective management requires an individualized, multi-pronged approach combining psychosocial and pharmacologic interventions. Understanding these core principles is essential for effective diagnosis, treatment, and support of patients with SUDs.
•In our next post we will begin to discuss specific SUDs, starting with Alcohol Use Disorder (AUD).
Resources for today's post include:
Articles referenced above
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