Self-reported exercise frequency and PTSD: results from the National Health and Resilience in Veterans Study.

OBJECTIVE: Physical exercise may serve as a protective factor for posttraumatic stress disorder (PTSD), but little is known about whether physical exercise is associated with PTSD in population-based samples of military veterans. METHODS: We analyzed cross-sectional data on the relation between self-reported physical exercise frequency and the prevalence of probable PTSD in a nationally representative sample of 2832 U.S. military veterans who participated in the National Health and Resilience in Veterans Study. RESULTS: A "U-shaped" association best explained the relation between self-reported exercise frequency and the prevalence of probable PTSD. Compared to veterans without probable PTSD, those with probable PTSD were nearly twice as likely to report no weekly exercise (52.3% vs. 29.3%) or daily (7 days/week) exercise (15.2% vs. 8.5%) and were nearly half as likely to report exercising a median of 3.5 days/week (32.6% vs. 62.1%). No exercise was associated with greater severity of emotional numbing and lower severity of anxious arousal symptoms, while daily exercise was associated with greater severity of re-experiencing symptoms. CONCLUSIONS: Results of this study suggest a "U-shaped" association between self-reported exercise frequency and the prevalence of probable PTSD among U.S. veterans. Veterans with probable PTSD were more likely than those without probable PTSD to report not exercising at all or exercising every day and were less likely to report exercising 1-6 days per week. Clinical implications of these findings are discussed.

The role of stress in the pathogenesis and maintenance of obsessive-compulsive disorder.

Individuals with OCD often identify psychosocial stress as a factor that exacerbates their symptoms, and many trace the onset of symptoms to a stressful period of life or a discrete traumatic incident. However, the pathophysiological relationship between stress and OCD remains poorly characterized: it is unclear whether trauma or stress is an independent cause of OCD symptoms, a triggering factor that interacts with a preexisting diathesis, or simply a nonspecific factor that can exacerbate OCD along with other aspects of psychiatric symptomatology. Nonetheless, preclinical research has demonstrated that stress has conspicuous effects on corticostriatal and limbic circuitry. Specifically, stress can lead to neuronal atrophy in frontal cortices (particularly the medial prefrontal cortex), the dorsomedial striatum (caudate), and the hippocampus. Stress can also result in neuronal hypertrophy in the dorsolateral striatum (putamen) and amygdala. These neurobiological effects mirror reported neural abnormalities in OCD and may contribute to an imbalance between goal-directed and habitual behavior, an imbalance that is implicated in the pathogenesis and expression of OCD symptomatology. The modulation of corticostriatal and limbic circuits by stress and the resultant imbalance between habit and goal-directed learning and behavior offers a framework for investigating how stress may exacerbate or trigger OCD symptomatology.

Disgust mediates the relation between attentional shifting and contamination aversion.

BACKGROUND AND OBJECTIVES: Aversion of contaminants is important for several psychiatric disorders, particularly contamination-based obsessive-compulsive disorder (OCD). Recent theoretical models have proposed that the ability to control one's attention, especially when processing affectively laden information, is important in the etiology of pathological anxiety. The present study tested the relations between attentional control, affective arousal, and behavioral approach toward contaminants (contamination aversion). METHODS: Thirty-three non-selected (undergraduate university students) participants completed a measure of trait attentional control and three behavioral approach tasks, which measured emotional reactivity and approach toward contaminants. RESULTS: Preliminary analyses showed that poorer attentional control and greater affective arousal predicted less behavioral approach toward contaminants. Modeling of direct and indirect relations showed that poor attentional shifting ability and greater subjective disgust were related to less behavioral approach. Moreover, disgust fully mediated the relation between attentional shifting and behavioral approach. LIMITATIONS: The present study used a convenience sample, which is not representative of the general population or individuals with OCD; therefore, research using clinical samples is necessary before making clinical interpretations. Moreover, the present study utilized subjective measures of attentional control and affective arousal. The use of objective measures of attention and affective arousal would provide a more valid test of the role of attentional control in contamination aversion. CONCLUSIONS: These findings suggest that attentional shifting abilities may serve as a vulnerability to affective arousal/regulation and behavioral avoidance of contaminants, but the latter relation only operated indirectly via disgust. These findings have clear implications for the etiology of contamination-related OCD.