Biological mechanisms in posttraumatic stress disorder. Relevance for substance abuse

A Theoretical Endogenous Opioid Neurobiological Framework for Co-occurring Pain, Trauma, and Non-suicidal Self-injury

PURPOSE OF REVIEW

Individuals with chronic pain are significantly more likely to have experienced overwhelming trauma early and often in key developmental years. There is increasing acknowledgment that childhood trauma disrupts how individuals process and cope with both physical and emotional pain. Emerging studies acknowledge elevated rates of non-suicidal self-injury (NSSI) in chronic pain populations. This review provides a theoretical framework to understand the relationship between NSSI behavior and pain experience in persons with chronic pain and childhood trauma histories. We discuss how NSSI may act to regulate neurobiological (e.g., endogenous opioid systems) and psychological (e.g., heightened negative affect and emotion dysregulation) systems affected by childhood trauma, leading to temporary pain relief and a cycle of negative reinforcement perpetuating NSSI. As these concepts are greatly understudied in pain populations, this review focuses on key areas relevant to chronic pain that may provide a testable, conceptual framework to support hypothesis generation, future empirical investigation, and intervention efforts.

RECENT FINDINGS

See Fig. 1. See Fig. 1.

Consideration of substance use in compensation and pension examinations of veterans filing PTSD claims

Veterans filing claims that service-induced PTSD impairs them worry that claims examiners may attribute their difficulties to conditions other than PTSD, such as substance use. Substance use commonly co-occurs with PTSD and complicates establishing a PTSD diagnosis because symptoms may be explained by PTSD alone, PTSD-induced substance use, or by a substance use condition independent of PTSD. These alternative explanations of symptoms lead to different conclusions about whether a PTSD diagnosis can be made. How substance use impacts an examiner’s diagnosis of PTSD in a Veteran’s service-connection claim has not been previously studied. In this study, we tested the hypothesis that mention of risky substance use in the Compensation & Pension (C&P) examination would result in a lower likelihood of service-connection award, presumably because substance use reflected an alternative explanation for symptoms. Data were analyzed from 208 Veterans’ C&P examinations, medical records, and confidentially-collected research assessments. In this sample, 165/208 (79%) Veterans’ claims were approved for a mental health condition; 70/83 (84%) with risky substance use mentioned and 95/125 (76%) without risky use mentioned (p = .02). Contrary to the a priori hypothesis, Veterans with risky substance use were more likely to get a service-connection award, even after controlling for baseline PTSD severity and other potential confounds. They had almost twice the odds of receiving any mental health award and 2.4 times greater odds of receiving an award for PTSD specifically. These data contradict assertions of bias against Veterans with risky substance use when their claims are reviewed. The data are more consistent with substance use often being judged as a symptom of PTSD. The more liberal granting of awards is consistent with literature concerning comorbid PTSD and substance use, and with claims procedures that make it more likely that substance use will be attributed to trauma exposure than to other causes.

Towards a unitary perspective between post-traumatic stress disorder and substance use disorder. Heroin use disorder as case study

BACKGROUND

Genetic, neurobiological, environmental and psychosocial mechanisms have received considerable attention in exploring the mechanisms that underlie comorbid PTSD and SUD. PTSD and SUD are not necessarily linked by a causal relationship, as the self-medication hypothesis had supposed. They might, in fact, both be caused by a third factor that predisposes these subjects to develop the two disorders (so allowing a unitary perspective).

METHODS

Using a conceptualization of the PTSD spectrum, we studied the PTSD-SUD unitary perspective by testing the correlation between severity of heroin addiction, dose of opioid medication and severity of PTSD spectrum in 82 methadone-treated, heroin-dependent patients.

RESULTS

Canonical correlation analysis (Wilks Lambda=0.125F=1.41 p=0.014), univariate and multivariate comparisons between subgroups, identified on the basis of addiction severity, showed a highly positive correlation between the PTSD spectrum and the severity of heroin addiction. In addition, negative correlations were found between PTSD spectrum severity and methadone dose (r=0.225; p=0.042).

CONCLUSIONS

This strength and breadth of the correlations encourage us to move towards a unified vision of the two disorders.

Noradrenergic vs serotonergic antidepressant with or without naltrexone for veterans with PTSD and comorbid alcohol dependence

The wars in Iraq and Afghanistan are associated with high rates of post-traumatic stress disorder (PTSD) and comorbid alcohol use disorders. The pharmacotherapy of these comorbid conditions has received relatively little study. The current study compared the serotonin uptake inhibitor, paroxetine, to the norepinephrine uptake inhibitor, desipramine. It also evaluated the adjunctive efficacy of the Food and Drug Administration (FDA)-approved alcoholism pharmacotherapy, naltrexone, relative to placebo. Four groups of predominately male veterans (n=88) meeting current diagnostic criteria for both alcohol dependence (AD) and PTSD were randomly assigned under double-blind conditions to one of four groups: paroxetine+naltrexone; paroxetine+placebo; desipramine+naltrexone; desipramine+placebo. Main outcome measures included standardized scales that assessed symptoms of PTSD and alcohol consumption. Paroxetine did not show statistical superiority to desipramine for the treatment of PTSD symptoms. However, desipramine was superior to paroxetine with respect to study retention and alcohol use outcomes. Naltrexone reduced alcohol craving relative to placebo, but it conferred no advantage on drinking use outcomes. Although the serotonin uptake inhibitors are the only FDA-approved medications for the treatment of PTSD, the current study suggests that norepinephrine uptake inhibitors may present clinical advantages when treating male veterans with PTSD and AD. However, naltrexone did not show evidence of efficacy in this population. This study was registered with ClinicalTrials.gov, registration number NCT00338962 and URL: http://clinicaltrials.gov/ct2/show/NCT00338962?term=desipramine+AND+alcohol+dependence+AND+depression&recr=Closed&rank=1.

Review of biological mechanisms and pharmacological treatments of comorbid PTSD and substance use disorder

Posttraumatic stress disorder (PTSD) and alcohol/substance use disorder (A/SUD) are frequently comorbid. Comorbidity is associated with poorer psychological, functional, and treatment outcomes than either disorder alone. This review outlines biological mechanisms that are potentially involved in the development and maintenance of comorbid PTSD and A/SUD including neurotransmitter and hypothalamic-pituitary-adrenal dysregulation, structural differences in the brain, and shared genetic risk factors. The literature regarding pharmacological treatments that have been investigated for comorbid PTSD and A/SUD is also reviewed. Empirical data for each proposed mechanism and pharmacological approach is reviewed with the goal of making recommendations for future research. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.

Posttraumatic stress disorder with and without alcohol use disorders: diagnostic and clinical correlates in a psychiatric sample

This study compared outpatients (n=196) with PTSD versus PTSD+alcohol use disorders (AUD) on clinical measures. PTSD+AUD patients were more likely to meet criteria for Borderline and Antisocial Personality Disorders. Emotion dysregulation may help account for the relationship between PTSD and AUD.

Young Investigator Award symposium

This article highlights the research presented at the inaugural meeting of Alcoholism and Stress: A Framework for future Treatment Strategies. This meeting was held on May 6-8, 2008 in Volterra, Italy. It is an international meeting dedicated to developing preventive strategies and pharmacotherapeutic remedies for stress- and alcohol-related disorders. For the first time, the National Institute on Alcohol Abuse and Alcoholism (NIAAA) conferred a Young Investigator Award to promote the work of young researchers and highlight their outstanding achievements in the fields of addiction medicine and stress disorders. The awardees were Dr. Katie Witkiewitz (University of Washington), Dr. Andrew Holmes (NIAAA), Dr. Lara A. Ray (Brown University), Dr. James Murphy (University of Memphis), and Dr. Heather Richardson (The Scripps Research Institute). The symposium was chaired by Drs. Fulton Crews and Antonio Noronha.

The role of endogenous opioids in the placebo effect in post-traumatic stress disorder

The concept of the placebo effect has received a considerable attention over the past several decades. The placebo effect has been observed in different psychiatric disorders, including post-traumatic stress disorder (PTSD), a chronic and severe disorder precipitated by exposure to a psychologically distressing event. The placebo response rates in patients with PTSD range from 19% to 62%. A considerable number of research publications suggest that endogenous opioids are involved in the mechanisms of the placebo effect. Endogenous opioid peptides play an important role in stress response and in the pathophysiology of PTSD. Therefore, endogenous opioids may be involved in the neurobiology of the placebo effect in PTSD. Possibly, the endogenous opioid system mediates the effect of placebo on all 3 PTSD symptom clusters (re-experiencing symptoms, avoidance and numbing, and physiologic arousal). The placebo effect-related activation of the endogenous opioid system may result in an improvement in intrusive symptomatology and symptoms of increased arousal because the administration of exogenous opioids improve these symptoms. The placebo effect-related activation of the endogenous opioid system may have a mood-enhancing effect, and, consequently, diminish avoidance and numbing. Multiple neurotransmitter and neuroendocrine pathways may be involved in the mechanisms of the placebo effect in PTSD. Further studies of the neurobiology of the placebo effect on patients with PTSD and other psychiatric disorders may produce interesting and important results.

"Transcend": initial outcomes from a posttraumatic stress disorder/substance abuse treatment program

This paper describes the development of a comprehensive treatment program for combat veterans diagnosed with posttraumatic stress disorder (PTSD) and substance abuse (SA). Outcome data are presented on 46 male patients who completed treatment between 1996 and 1998. The treatment approach, defined by a detailed manual, integrates elements of cognitive-behavioral skills training, constructivist theory approaches, SA relapse prevention strategies, and peer social support into a group-focused program. The Clinician-Administered PTSD Scale (CAPS) and the Addiction Severity Index (ASI) were used to assess treatment effectiveness at discharge and 6- and 12-month follow-up. Significant symptom changes revealed on CAPS and ASI scores at discharge and follow-up are analyzed. Discussion focuses on hypotheses regarding treatment effectiveness, study limitations, and suggestions for further research.

Chronicity in posttraumatic stress disorder (PTSD) and predictors of course of comorbid PTSD in patients with anxiety disorders

The purpose of this study was to examine the course of comorbid posttraumatic stress disorder (PTSD) in 54 patients with another anxiety disorder. Using a prospective longitudinal design, the present study found that during the first 5 years of follow-up the probability of full remission from a chronic episode of PTSD was .18. Findings from this and other research confirm clinical impressions that a substantial number of people never fully remit from their PTSD even after many years. Variables associated with a longer time to remit from an episode of chronic PTSD were a history of alcohol abuse and a history of childhood trauma.

Investigations of causal pathways between PTSD and drug use disorders

Although numerous studies have demonstrated an association between PTSD and substance use disorders, little is known about the causal nature of this relationship. In this article, we put forth and test major causal hypotheses. Specific hypotheses to be tested include self-medication of PTSD symptoms, substance users' high risk of exposure to traumatic events, and drug users' increased susceptibility to PTSD following a traumatic exposure. We also examine the possibility of an indirect pathway linking drug use disorders and PTSD via a shared vulnerability. Evidence for these causal hypotheses is evaluated using Hill's criteria for causal inference: strength, consistency, specificity, temporality, gradient, plausibility, coherence, experimental evidence, and analogy. We present data analytic strategies that exploit information about the temporal order of PTSD and drug use disorders to shed light on their causal relationship. Finally, we present findings on the PTSD/drug use disorder association from an epidemiologic study of young adults.

Maternal and child posttraumatic stress disorder in cases of child maltreatment

The purpose of this study was to examine the rates of posttraumatic stress disorder (PTSD) among a sample of severely maltreated children and their mothers, and to investigate the age of onset of documented maltreatment in these children. The sample consisted of 109 pairs of women and their children who were before a juvenile/family court due to maltreatment of sufficient severity to warrant removal of the child from parental custody. Children were examined using the PTSD Section of the Diagnostic Interview for Children and Adolescents, Revised 6th Version (DICA-6-R). The PTSD Module of the Structured Clinical Interview for DSM-III-R (SCID) was administered to all mothers. Clinical psychiatric interviews were also administered to all children and mothers. From the sample of 109 cases, 15.6% of the mothers met SCID criteria for a current presentation of PTSD, while 36.7% had a past history of PTSD. Of the 109 evaluated children, 35.8% met current DICA criteria for PTSD. Posttraumatic stress disorder is significantly overrepresented in the children of mothers diagnosed with PTSD (p = .001). The average age of maltreatment onset was 46.4 months among the children diagnosed as PTSD, and was 61.3 months in the group of seriously maltreated children who did not develop PTSD (p = .038). The onset of maltreatment is significantly earlier among children whose mothers meet PTSD criteria than among other maltreated children (p = .025). Intergenerational transmission of violence and developmental effects of traumatic experiences upon the young child are discussed.

Alcoholism and drug abuse in patients with PTSD

The combination of PTSD and substance abuse is both common and problematic. In this chapter we review the following questions: 1) What is the relationship between PTSD, Alcoholism, and Drug Abuse? 2) Can the general "dual diagnosis" literature be of help? 3) Is the phenomenology of PTSD combined with alcoholism and/or drug abuse either unique or specific? 4) Does current pathophysiologic data allow conceptualization of a neurobiological model of PTSD, alcoholism, and drug abuse? 5) Drawing on these ideas, on the limited treatment literature, and the "dual diagnosis" literature, can we develop rational assessment and treatment approaches? Available literature suggests that diagnoses can be validly applied to these patients; that the illnesses must be treated simultaneously as co-primary illnesses; that extreme psychological symptoms reduce the efficacy of alcoholism or drug abuse treatment; and that effective control of these symptoms improves treatment outcome.