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The current conflicts in Iraq and Afghanistan have resulted in a large cohort of military personnel exposed to combat-related psychological trauma as well as biomechanical trauma, including proximity to blast events. Historically, the long-term effects of both types of trauma have been viewed as having different neural substrates, with some controversy over the proper attribution of such symptoms evident after each of the major conflicts of the last century. Recently, great effort has been directed toward distinguishing which neuropsychiatric sequelae are due to which type of trauma. Of interest, however, is that the chronic effects of exposure to either process are associated with a significant overlap in clinical symptoms. Furthermore, similar brain regions are vulnerable to the effects of either psychological or biomechanical trauma, raising the possibility that shared mechanisms may underlie the clinically observed overlap in symptom profile. This paper reviews the literature on the neural substrate of biomechanical and psychological injury and discusses the implications for evaluation and treatment of the neuropsychiatric sequelae of these processes.

AbstractPeople differ markedly in their risk for developing posttraumatic stress symptoms (PTSS) after exposure to traumatic events. Twin studies suggest that the trauma-PTSS relationship is moderated by genetic and environmental influences. The present study tested for specific types of genetic and environmental interaction effects on PTSS. A sample of 222 monozygotic and 184 dizygotic twin pairs reported on lifetime frequency of assaultive and nonassaultive trauma and associated PTSS. Biometric analyses indicated that in the case of nonassaultive trauma, PTSS were directly affected by environmental factors that also influence exposure to nonassaultive trauma. For assaultive trauma both genetic and non-shared environmental influences jointly affected PTSS, and the number of traumatic events moderated the severity of PTSS. Genetic factors were found to become less important beyond some threshold (e.g., 3 or 4 types of serious trauma) suggesting that genetic factors — which may confer either risk or resilience to PTSS — modify these symptoms within a range of human experience, beyond which environmental effects supervene.

OBJECTIVES: Research suggests a high prevalence of problematic alcohol use among military personnel relative to civilians. Our primary objectives were to compare the prevalence, correlates, help-seeking behaviors, perceived need for care, and barriers to care for alcohol use disorders (AUDs) in the Canadian Armed Forces (CAF) and the Canadian general population (CGP). METHODS: Data were from 2 nationally representative surveys collected by Statistics Canada: (1) the Canadian Community Health Survey on Mental Health collected in 2012 (N = 25,113; response rate = 68.9%) and (2) the Canadian Forces Mental Health Survey collected in 2013 (N = 8,161; response rate = 79.8%). Descriptive statistics and logistic regression were used to examine differences in outcomes of interest associated with AUDs in the CAF and CGP. RESULTS: The prevalence of lifetime AUDs was significantly higher in the CAF (32.0%) than the CGP (20.3%; adjusted odds ratio [AOR] = 1.14, 95% confidence interval [CI, 1.02 to 1.27]) after adjustment for sociodemographic covariates. In contrast, the past-year prevalence of AUDs was significantly lower among CAF personnel (4.5%) than civilians (3.8%; AOR = 0.78, 95% CI [0.61 to 0.99]) after adjustment for sociodemographic covariates. Child abuse history and comorbid mental disorders were strongly associated with past-year AUDs in both populations. CAF personnel compared to the CGP were more likely to perceive a need for care (AOR = 4.15, 95% CI [2.56 to 6.72]) and engage in help-seeking behaviors (significant AORs ranged from 1.85 to 5.54). CAF personnel and civilians with past-year AUDs reported different barriers to care. CONCLUSIONS: Findings argue for the value of different approaches to address unmet need for AUD care in the CAF and CGP.

Posttraumatic stress disorder (PTSD)—a chronic, debilitating condition, broadly characterized by emotion dysregulation—is prevalent among US military personnel who have returned from Operations Enduring Freedom (OEF) and Iraqi Freedom (OIF). Selective serotonin reuptake inhibitors (SSRIs) are a first-line treatment for PTSD, but treatment mechanisms are unknown and patient response varies. SSRIs may exert their effects by remediating emotion regulatory brain activity and individual differences in patient response might be explained, in part, by pre-treatment differences in neural systems supporting the downregulation of negative affect. Thirty-four OEF/OIF veterans, 17 with PTSD and 17 without PTSD underwent 2 functional magnetic resonance imaging scans 12 weeks apart. At each scan, they performed an emotion regulation task; in the interim, veterans with PTSD were treated with the SSRI, paroxetine. SSRI treatment increased activation in both the left dorsolateral prefrontal cortex (PFC) and supplementary motor area (SMA) during emotion regulation, although only change in the SMA over time occurred in veterans with PTSD and not those without PTSD. Less activation of the right ventrolateral PFC/inferior frontal gyrus during pre-treatment emotion regulation was associated with greater reduction in PTSD symptoms with SSRI treatment, irrespective of pre-treatment severity. Patients with the least recruitment of prefrontal emotion regulatory brain regions may benefit most from treatment with SSRIs, which appear to augment activity in these regions.

Introduction: This study examined the prevalence, clinical characteristics, help seeking patterns, and military experiences associated with past-year generalized anxiety disorder (GAD) using a representative sample of military personnel. Methods: Data were from the Canadian Community Health Survey–Canadian Forces Supplement ( n = 5,115 Regular Force, n = 3,286 Reserve Force), conducted by Statistics Canada on behalf of the Department of National Defence in 2002. GAD and other mental disorders were assessed using the World Mental Health Composite International Diagnostic Interview. Clinical features of GAD of interest included mean age of onset and episode length, symptoms, degree of impairment and co-occurring disorders, and perceived need for help and help seeking. Multivariate logistic regression models were conducted to examine the sociodemographic, military characteristics, and mental disorders correlated with past-year GAD. Results: Past-year and lifetime prevalence rates of GAD were 1.7% and 4.4%, respectively. The majority of military personnel with past-year GAD reported being severely impaired at work and in their relationships and social life. Those with past-year GAD, relative to those without it, had higher odds of having another mental disorder. Of military personnel with past-year GAD, 72.2% had sought help. Regular Force personnel, relative to reservists, had higher odds of having past-year GAD, as did individuals who witnessed atrocities. Discussion: GAD is modestly prevalent in the Canadian military and is associated with considerable functional impairment. Nevertheless, high rates of help seeking for GAD may speak to the availability, accessibility, and acceptability of mental health care in the Canadian Armed Forces.

Objectives. We investigated mental disorders, suicidal ideation, self-perceived need for treatment, and mental health service utilization attributable to exposure to peacekeeping and combat operations among Canadian military personnel.

Mixed-mode surveys need to determine a number of design parameters that may have a strong influence on costs and errors. In a sequential mixed-mode design with web followed by telephone, one of these decisions is when to switch modes. The web mode is relatively inexpensive but produces lower response rates. The telephone mode complements the web mode in that it is relatively expensive but produces higher response rates. Among the potential negative consequences, delaying the switch from web to telephone may lead to lower response rates if the effectiveness of the prenotification contact materials is reduced by longer time lags, or if the additional e-mail reminders to complete the web survey annoy the sampled person. On the positive side, delaying the switch may decrease the costs of the survey. We evaluate these costs and errors by experimentally testing four different timings (1, 2, 3, or 4 weeks) for the mode switch in a web–telephone survey. This experiment was conducted on the fourth wave of a longitudinal study of the mental health of soldiers in the U.S. Army. We find that the different timings of the switch in the range of 1–4 weeks do not produce differences in final response rates or key estimates but longer delays before switching do lead to lower costs.