Post-traumatic stress disorder and substance use disorders
Post-traumatic stress disorder can affect about 3.6% of the U.S. population each year, and 6.8% of the U.S. population over a lifetime. 8.4% of people in the U.S. are diagnosed with substance use disorders. Of those with a diagnosis of PTSD, a co-occurring, or comorbid diagnosis of a SUD is present in 20–35% of that clinical population.
Prevalence of SUD and PTSD may increase depending on specific populations. For example, the prevalence of both PTSD and SUD is higher in combat veterans. Other populations that are disproportionately affected by both of these disorders include women, members of the black and hispanic populations, and members of the LGBTQ community.Alcohol use disorder is the leading cause of SUD amongst veterans who have experienced trauma. While research indicates that alcohol is the most abused substance by those diagnosed with PTSD, additional substances with high abuse rates include other depressants such as cannabis and opiates, as well as the stimulant cocaine."
Worsening PTSD symptoms are associated with increased SUD and poor treatment response Of those with a SUD diagnosis, current PTSD is present in 25–50%, and lifetime PTSD is present in 15–40%, averaging 30% overall. Though roughly a third of all people diagnosed with SUD also have PTSD, there is not yet consistent protocol for SUD treatment centers to screen for both PTSD and SUD symptomology upon intake.
The presence of both PTSD and SUD can hinder outcomes of those seeking treatment for either PTSD or SUD. A few different treatment options include trauma focused treatments such as psychotherapy, non trauma focused treatments, and pharmacological treatments like medications that can help reduce withdrawal symptoms or SSRIs.Those who experience both diagnoses may generally have poorer overall functioning and worse overall well-being than each diagnosis by itself. This can manifest as being hospitalized more frequently, experiencing increased levels of legal issues, have less social support, and have a harder time retaining employment. In treatment these individuals can have high dropout rates, respond poorly to the treatment of PTSD in general, have greater levels of addiction severity, and shorter periods of remission for substance use treatment.
Etiological theory
Each of the subsequent theories about the causal link between PTSD and SUD have varying levels of empirical support. These etiological theories are not mutually exclusive, and features of more than one can be present for an individual with dual diagnoses of SUD and PTSD. No one clear etiological link has been established between SUD and PTSD.Susceptibility hypothesis
The susceptibility hypothesis suggests that the substance use may increase the risk of PTSD developing after a traumatic event. Individuals who use substances may lack appropriate coping mechanisms to deal with daily stressors before the traumatic event, they may be less equipped than individuals who do not use substances to cope with extreme stress. Thus, these individuals may be more susceptible to developing PTSD following a traumatic event.Implication of coping strategies
Coping style has recurrently been discussed as a third-party influence on the presence of dual diagnosis for PTSD and SUD. Avoidant coping styles have been shown to have a strong relationship to both PTSD and SUD individually, as well as presentation of concomitant PTSD and SUD together. Those with avoidant coping styles attempt to avoid interacting with or experiencing thoughts, feelings, or physical sensations reminiscent of the stressor in order to gain relief from the distress it causes. Substance use, for example, can allow a person to attempt to escape the distressing thoughts, feelings or physical sensations associated with the stressor the person is attempting to avoid experiencing. An avoidant coping style can therefore increase an individual's likelihood to seek means to avoid experiencing distressing sensations and increase likelihood of substance use overall.PTSD affects substance use disorders
Individuals with comorbid PTSD and SUD tend to engage in more frequent and heavier substance use than individuals who have SUD alone. Additionally, research suggests that symptoms of PTSD can hinder abstaining from substance use. More generally, individuals with a dual diagnosis of PTSD and SUD have shown to be at increased risk meeting criteria for other psychiatric diagnosis in additional to PTSD and SUD when compared to those with SUD alone. Those with a dual diagnosis of PTSD and SUD have also been shown to seek treatment at higher rates than those who experience SUD alone.How substance use disorders affect PTSD
The self medication hypothesis, as well as behavioral and emotional conditioning plays a role for people with dual diagnoses of PTSD and SUD. Symptoms of withdrawal, increased heart rate, sweating can mirror a human's natural physiological responses to fear, and can therefore trigger fear responses associated with that person's traumatic experience. Those with comorbid PTSD and SUD diagnoses may seek to avoid experiencing withdrawal to avoid experiencing these sensations that can act as fear inducing and triggering experiential catalysts. Additionally, individuals who chronically use substances as a form of self-medication for PTSD symptoms strengthen an automatic mental link between PTSD symptoms and the substance use itself via conditioning. Stress is also a component of PTSD that may lead to drug use, due to the norepinephrine that is released from the stress response of the body. Therefore, conditioned link between PTSD and substance use may trigger craving for substances when it arises, potentially increasing psychological dependence and complicating treatment outcomes for both diagnoses.Implicated brain systems
Hippocampus and amygdala
The hippocampus, which is responsible for encoding memory within the brain, is implicated in both PTSD and SUD. PTSD and SUD have been found to interfere with typical hippocampal functioning. Studies of the involvement of the hippocampus in both sole PTSD and SUD diagnosis as well as comorbid PTSD and SUD evidence that the manifestation of these diagnosis are related to decreased hippocampal volume.Hypothalamic pituitary adrenal axis and corticotropin-releasing hormone. The hypothalamic pituitary adrenal axis is responsible for the activation of the hormonal stress response system within the human body. Corticotropin-releasing hormone is activated by the HPA axis during times of stress. Heightened CRH levels have been shown during symptoms of PTSD, drug seeking behavior, substance withdrawal, and drug relapse in humans. Research has conveyed that increased levels of CRH are also related to experiences of euphoria. As CRH levels are elevated in PTSD, this can personify feelings of euphoria experienced when an individual uses substances and increase addiction severity as a result of positive reinforcement from euphoric sensation. This can also affect the interplay between withdrawal symptoms and the increased experience of hyperarousal. As increased levels of CRH have been linked to both withdrawal and hyperarousal, those affected by both diagnoses of PTSD and SUD may subsequently continue to seek substances as a means to avoid these escalated aversive sensations. The described relationship has been used to evidence the self-medication hypothesis.