NEUROBIOLOGY OF SUBSTANCE USE DISORDERS
Substance use disorders (SUDs) are complicated physiologic and psychologic disorders with multiple intersecting factors, such as drug use behaviors and poor judgment influenced by the phar - macodynamics and pharmacokinetic actions of the drug (Boland & Verduin, 2022). The central element of drug dependence is drug-using behavior. Drug use initiates a cascade of rewarding or aversive physical, psychological, and social consequences that determine the likelihood of subsequent use (Boland & Verduin, 2022). The development and persistence of SUDs are primarily based on key components within the basal ganglia, amygdala (extended), and prefrontal cortex (U.S. Department of Health and Human Services [HHS], 2016). The basal ganglia and its subnetworks are responsible for reward, pleasure, and the formation of habitual substance use (HHS, 2016). The amygdala is responsible for un- easy feelings, anxiety, and withdrawal irritability. The prefrontal cortex is involved in executive function and exerts control over the individual’s cognitive inability to reject substance use based on neurocircuitry, namely impulsivity and compulsivity (Stahl, 2020). These endophenotypes are found trans-diagnostically present across many psychopathologies. Impulsivity causes the individual to act without forethought and with lack of reflection on previous behavior. Compulsivity is char - acterized by inappropriate actions which persist regardless of Implicit bias and stigma in substance use disorders The language used by clinicians, such as addicts , can stigmatize individuals with substance use disorders reflecting misconcep - tions that these behaviors are choices rather than compulsions (NIDA, 2022). Negative biases can dehumanize individuals and affect the therapeutic alliance, and, ultimately, the course of re- covery (NIDA, 2022). Clinicians who stereotype drug use as a criminal activity marginalize disadvantaged groups and negatively
the situation (Stahl, 2020). Over time, impulsive substance use becomes compulsive addiction as this dysregulation becomes a dependent conditioned response. The impulses in the ventral loop of reward and motivation migrate dorsally because of neuro- plasticity and engage in a habit system, creating the conditioned response of addiction (Stahl, 2020). Impulsive drug use produces a high , which, if experienced too often, cause the migration to compulsive use (addiction) to reduce the unpleasant effects of withdrawal. The mesolimbic pathway is hypothesized to be the final common pathway of reward and reinforcement in the brain, where all addictive drugs increase dopamine, especially with ha- bitual use (Stahl, 2020; Wise & Jordan, 2021). Arising in the ven- tral tegmental area (VTA), it projects into the nucleus accumbens (NA) and prefrontal cortex (PFC). The psychology of substance use disorders reflects psychodynam - ic theories dating back 100 years (Boland & Verduin, 2022). Dis- turbed ego functions, self-medication, and alexithymia (inability to describe feelings) are common among substance users. Aside from pharmacologic effects, positive reinforcement is gained from paraphernalia and associated behaviors with drug use (Boland & Verduin, 2022). Conditioned responses (similar to Pavlovian phe- nomena), such as cravings and withdrawal, promote relapsing be- haviors (Boland & Verduin, 2022). Individuals aged 18-24 years have a high prevalence rate for every substance disorder. influence treatment plans, which may increase drug use (NIDA, 2022.) Stigma and implicit biases impact fear of disclosing sub- stance use, decreased quality of care, or reduced access to care (NIDA, 2022). To this end, the word addiction has been eliminated from the DSM-5® (Diagnostic and Statistical Manual of Mental Disorders , 5th ed.) in favor of the more neutral term substance use disorder (APA, 2013).
Healthcare Considerations: Every member of our community may help to lessen stigma and prejudice against those who suffer from drug use disorders by: ● Understanding substance use disorders are chronic, treatable medical conditions. ● Changing stigmatizing language with more empowering, preferred language that does not equate people with their condition or have negative connotations. ● Addressing systemic racism, sexism, and other forms of discrimination leads to multiple layers of stigma for many people with ad- diction. (NIDA, 2022) Risk factors for substance use disorders Adult risk factors for substance use disorders include the following:
• Ability to afford drugs. • Avoidant coping style. • Bereavement. • Caucasian ethnicity, • Chronic pain.
• Poor health status. • Significant drug burden/polypharmacy. • Unexpected or forced retirement. • Social isolation (living alone or with nonspousal others). • History of alcohol problems. • Previous or concurrent substance use disorder. • Previous or concurrent psychiatric illness. (Kuerbis, 2020)
• Chronic physical illness/comorbidity. • Physical disabilities or reduced mobility. • Transitions in care/living situations.
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