Substance Use Disorders

Substance Use Disorders

• Substance use disorders are complex, chronic, relapsing, and remitting diseases linked to significant morbidity and mortality.
• Disorders involve three domains: medical, psychiatric, and substance use.

Diagnostic Assessment

• Objective Domain: Initial screening, mental status exam, physical exam, diagnostic tools (labs/imaging) are crucial.
• Medical: Medical conditions can mimic substance use disorder symptoms (intoxication, withdrawal, chronic use).
• Psychiatric: Psychiatric conditions (anxiety, depression, insomnia, flashbacks, memory problems) can mimic substance use disorders.
• Substance Use Domain: Assess substance use history using open-ended questioning, moving to a systemic approach including all substances (prescribed & non-prescribed), timing, frequency, route of administration.
• Assess social situations contributing to or exacerbating substance use (e.g., divorce, loss).
• Immediate Facts Needed: Substances used, frequency, amount, route, time of last use, alcohol/benzodiazepine withdrawal history.
• Assessment Facts: Age of first use, changes in use patterns, longest period of abstinence, treatment history, family history, overdose history.
• Further Facts and Feelings: Patient's perception of substance use as a problem, positive/negative aspects, motivation for change, financial consequences, triggers, adaptive strategies.
• Diagnosis: Requires at least 2 criteria; Mild (2-3 criteria), Moderate (4-5), Severe (6+).

Theories of Addiction

Brain Disease Model

• Binge/Intoxication: Dopamine increase, endogenous opioids & cannabinoids involved, reward circuitry (basal ganglia).
  • Behavior model: Positive reinforcement, Incentive sensitization.
• Withdrawal/Negative Effect: Corticotropin-releasing factor, Noradrenaline, Dynorphin, Vasopressin, Substance P increase, dopamine decrease, Hypothalamic-pituitary-adrenal axis affected.
  • Behavior model: Negative reinforcement, Conditioning.
• Preoccupation/Anticipation: Glutamate and GO systems increase, STOP systems decrease; impairments in decision-making, self-regulation, and behavioral inhibition (impacting relapse).
  • Behavior model: Habit Forming.
• Genetic Model: Increased CREB and FosB, polygenicity; vulnerability to addiction.
  • FosB: Protein regulating transcription in response to stimuli (stress, cytokines, etc.).

Neurobiological Factors

• Brain Reward Pathways: Addiction affects brain reward circuitry (mesolimbic dopamine pathway). Substances/behaviors increase dopamine in the nucleus accumbens, creating pleasure.
• Neurotransmitter Systems: Glutamate (learning, memory & addiction-related memories), GABA, serotonin, endogenous opioids also contribute.
• Changes in Brain Structure/Function: Prolonged use alters prefrontal cortex (decision-making, impulse control), impacting rational substance use choices, contributing to compulsive behaviors.

Psychosocial Factors

• Social Environment: Family, peers, socio-economic factors influence addiction risk. Limited support, peer pressure increase risk.
• Early Life Experiences: Trauma (abuse, neglect, family substance use) increase vulnerability. Adverse childhood experiences (ACEs) can disrupt stress response systems and increase substance use as coping mechanism.
• Mental Health/Coping Mechanisms: Conditions (anxiety, depression, PTSD, ADHD) may lead to substance use as self-medication. Maladaptive coping strategies reinforce addictive behaviors.

Epigenetic Factors

• Gene-Environment Interactions: Environmental factors alter gene expression without changing DNA sequence (epigenetic changes). Substance use causes epigenetic changes impacting stress response, reward sensitivity, and decision-making.
• Intergenerational Transmission: Epigenetic changes may pass down through generations (parents' exposure -> offspring's susceptibility).
• Stress & Epigenetic Modification: Chronic stress can alter epigenetic control, making the brain more vulnerable to addiction. Modification may result in long-term stress response changes, potentially increasing substance use as a coping mechanism.
• Interaction of These Factors: The interplay among these factors creates a cumulative effect.

Physician Role

• Physicians are often first points of contact & play a crucial role in lowering stigma.
• Stigma and perception of substance use disorders as a choice challenges effective care.
• Some physicians find substance use disorder care less fulfilling and challenging compared to other illnesses.

Epidemiology

• Substance use disorder prevalence (alcohol & drugs) is lower in Mexico compared to the US.