Semantic knowledge attenuates age-related differences in event segmentation and episodic memory.

While semantic and episodic memory may be distinct memory systems, their interdependence is substantial. For instance, decades of work have shown that semantic knowledge facilitates episodic memory. Here, we aim to clarify this interactive relationship by determining whether semantic knowledge facilitates the acquisition of new episodic memories, in part, by influencing an encoding mechanism, event segmentation. In the current study, we evaluated the extent to which semantic knowledge shapes how people segment ongoing activity and how such knowledge-related benefits in segmentation affect episodic memory performance. To investigate these effects, we combined data across three studies that had young and older adults segment and remember videos of everyday activities that were either familiar or unfamiliar to their age group. We found age-related differences in event-segmentation ability and memory performance, but only when older adults lacked semantic knowledge. Most importantly, when they had access to relevant semantic knowledge, older adults segmented and remembered information similar to young adults. Our findings indicate that older adults can use semantic knowledge to effectively encode and retrieve everyday information. These effects suggest that future interventions can leverage older adults' intact semantic knowledge to attenuate age-related deficits in event segmentation and episodic long-term memory.

Depression and Cognitive Dysfunction in Older U.S. Military Veterans: Moderating Effects of BDNF Val66Met Polymorphism and Physical Exercise.

OBJECTIVE: Depression is associated with increased risk for cognitive dysfunction, yet little is known about genetic and behavioral factors that may moderate this association. Using data from a nationally representative sample of older U.S. military veterans, we examined the direct and interactive effects of depression, brain-derived neurotropic factor (BDNF) Val66Met genotype, and physical exercise on cognitive functioning. METHODS: One thousand three hundred eighty-six older European-American U.S. military veterans (mean age = 63) completed a web-based survey and cognitive assessment. Analyses of covariance were conducted to evaluate the effects of depression, BDNF Met allele carrier status, and physical exercise on these measures. RESULTS: Depressed veterans scored worse than nondepressed veterans on subjective measures of cognitive functioning (Cohen d's = 0.34-0.57) and objective measures of visual learning (d = 0.39) and working memory (d = 0.28). Among depressed veterans, those who were Met allele carriers scored worse than Val/Val homozygotes on subjective cognitive measures (d's = 0.52-0.97) and an objective measure of visual learning (d = 0.36). Engagement in physical exercise moderated the association between depression and cognitive function, with depressed exercisers scoring better than depressed nonexercisers on a subjective measure of reasoning, and objective measures of processing speed, attention, and visual learning (d = 0.58-0.99): further, in depressed Met allele carriers, exercisers scored better than nonexercisers on subjective cognitive (d's = 0.80-1.92), and objective measures of visual learning (d = 0.8-1.31) and working memory (d = 0.67). CONCLUSION: Depression is associated with moderate decrements in cognitive functioning in older U.S. military veterans, and this association is moderated by BDNF Val66Met genotype and physical exercise. Prevention and treatment efforts designed to promote physical exercise may help preserve cognitive functioning in at-risk veterans.

Retrospective Appraisals Mediate the Effects of Combat Experiences on PTS and Depression Symptoms in U.S. Army Medics.

A life-threatening traumatic experience can cause physical and psychological distress, but it can also be remembered with pride from having demonstrated one's courage and abilities under severe circumstances. Characteristics of the event, early response, as well as later personal reflection, together determine the individual's response to a traumatic event. We investigated how traumatic combat experiences and retrospective appraisals of those experiences affected reports of symptoms of posttraumatic stress and depression in 324 U.S. Army medics. Higher levels of combat experiences were associated with both appraisals of threat to life (r = .40) and appraisals of personal benefit of the deployment (r = .15). Threat appraisals were associated with increases (r = .33 and .29), whereas benefit appraisals were associated with decreases (r = -.28 and -.30, respectfully), in symptoms of posttraumatic stress and depression. These opposing mediation pathways led to weak or nonsignificant total effects, which concealed the effects of combat intensity on posttraumatic stress (R(2) = .28) and depression (R(2) = .24). Acknowledging the beneficial effects that a combat experience had on one's life was associated with less intense behavioral health symptoms and offset the detrimental effects of traumatic combat experiences.

Cueing natural event boundaries improves memory in people with post-traumatic stress disorder.

People with post-traumatic stress disorder (PTSD) often report difficulty remembering information in their everyday lives. Recent findings suggest that such difficulties may be due to PTSD-related deficits in parsing ongoing activity into discrete events, a process called event segmentation. Here, we investigated the causal relationship between event segmentation and memory by cueing event boundaries and evaluating its effect on subsequent memory in people with PTSD. People with PTSD (n = 38) and trauma-matched controls (n = 36) watched and remembered videos of everyday activities that were either unedited, contained visual and auditory cues at event boundaries, or contained visual and auditory cues at event middles. PTSD symptom severity varied substantial within both the group with a PTSD diagnosis and the control group. Memory performance did not differ significantly between groups, but people with high symptoms of PTSD remembered fewer details from the videos than those with lower symptoms of PTSD. Both those with PTSD and controls remembered more information from the videos in the event boundary cue condition than the middle cue or unedited conditions. This finding has important implications for translational work focusing on addressing everyday memory complaints in people with PTSD.

Training, deployment preparation, and combat experiences of deployed health care personnel: key findings from deployed U.S. Army combat medics assigned to line units.

OBJECTIVE: To describe the perceptions of training and deployment preparation and combat experiences and exposures of U.S. Army combat medics. METHODS: Data were from the first year of a 3-year longitudinal study designed to assess the impact of combat on the behavioral health and resilience of 347 combat medics surveyed 3 to 6 months after returning from a 12-month deployment to Operation Enduring Freedom/Operation Iraqi Freedom theatre and assigned to brigade combat teams. RESULTS: Analyses indicated that combat medics may benefit from better preparation in types of shifts required during deployment, type and intensity of combat likely to be seen and experienced, more adequate training in the area of stress and mental health care management, and easier access to behavioral mental health care. CONCLUSIONS: The military has shown considerable progress in addressing and understanding the mental health care needs of Soldiers. However, challenges remain. Additional emphasis should be placed on reducing the stigma and barriers related to mental health care both in theatre and garrison and on developing an evidence-based, validated program for medics and other Soldiers to recognize stress and mental health issues on the battlefield. For medics, this should be from two perspectives-that of a combat Soldier and that of a medical provider.

PTSD is associated with impaired event processing and memory for everyday events.

Current theories of posttraumatic stress disorder (PTSD) propose that memory abnormalities are central to the development and persistence of symptoms. While the most notable memory disturbances in PTSD involve memory for the trauma itself, individuals often have trouble remembering aspects of everyday life. Further, people with PTSD may have difficulty segmenting ongoing activity into discrete units, which is important for our perception and later memory of the activity. The current study investigated whether PTSD diagnosis and symptom severity predicted event segmentation and memory for everyday activities. To do so, 63 people with PTSD and 64 controls with a trauma history watched, segmented, and recalled videos of everyday activities. Viewers with higher PTSD symptom severity showed lower agreement on locations of event boundaries and recalled fewer fine-grained actions than did those with lower symptom severity. These results suggest that PTSD symptoms alter event segmentation, which may contribute to subsequent memory disturbances.

BDNF Val66Met polymorphism and posttraumatic stress symptoms in U.S. military veterans: Protective effect of physical exercise.

The Met allele of the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism is associated with reduced levels of BDNF release, heightened hypothalamic-pituitary-adrenal axis reactivity, and impaired fear extinction. As a result, Met allele carriers may be at risk for greater severity of posttraumatic stress disorder (PTSD) symptoms. In this study, we examined the relationship between the BDNF Val66Met polymorphism and PTSD symptoms in two nationally representative samples of European American U.S. military veterans (main sample, n = 1386; replication sample, n = 509). Results revealed that, relative to Val/Val homozygotes, Met allele carriers reported greater severity of lifetime and current PTSD symptoms, specifically re-experiencing symptoms. Met allele carriers with high trauma burden also reported greater severity of lifetime and past-month PTSD symptoms. Greater engagement in physical exercise moderated this gene-by-environment interaction. Specifically, among veterans with high lifetime trauma burden, Met allele carriers who exercised had significantly lower severity of PTSD symptoms compared to those who did not exercise. These findings suggest that interventions designed to bolster engagement in physical exercise may help mitigate PTSD symptoms in veterans who are Met allele carriers and highly exposed to trauma.

Risk Factors for Suicidal Behavior Depend on Age for Veterans in the Pacific Islands.

We examined whether risk factors for suicidal behavior depend on age among military veterans in the Pacific Islands (N = 29,595). For veterans under 54 years old, having a diagnosis of posttraumatic stress disorder, borderline personality disorder, a drug use disorder, and having a service-related disability predicted suicidal behavior. For veterans 54 years old or older, having a mood disorder predicted suicidal behavior. Having a history of suicidal behavior and a high number of VA health care visits were associated with suicidal behavior for both age groups. Our findings suggest that the predictive value of certain risk factors in veterans in the Pacific Islands may depend on age.

Gender differences in combat medic mental health services utilization, barriers, and stigma.

Military health care providers experience considerable stressors related to their exposure to death and traumatic injuries in others. This study used survey data from 799 active duty U.S. Army Combat Medics deployed to Operation Iraqi Freedom/Operation Enduring Freedom. Military experiences, combat exposures, and mental health care seeking of active duty Combat Medics were explored and compared across both genders. Barriers to care were also assessed. Male and female Combat Medics reported surprisingly similar experiences, exposures, and health issues. Overall, results indicate no striking differences in barriers for females compared to their male counterparts, suggesting the barriers to utilization of mental health services may be consistent across gender. Although medics endorsed barriers and stigma related to mental health counseling services, they still sought these health services. Female and male medics who endorsed barriers were more likely to report seeking services than those who did not endorse barriers. This study provides an initial description of utilization of mental health counseling services for U.S. Army Combat Medics, the majority of whom were involved in combat operations in Afghanistan or Iraq. Our findings indicate that comprehensive assessment of the military experiences and combat exposures is needed to appreciate their potential influence on military health care providers.