Posttraumatic stress symptoms across the deployment cycle: A latent transition analysis.

Our objective was to examine symptom-level changes in the course in posttraumatic stress disorder (PTSD) across the deployment cycle among combat-exposed Marines, and to determine the degree to which combat exposure and post-deployment stressor exposure predicted PTSD symptom profile transitions. We examined PTSD symptoms in a cohort of U.S. Marines (N = 892) recruited for the Marine Resiliency Study (MRS). Marines deployed as one battalion infantry unit to Afghanistan in 2010 and were assessed pre-deployment and one, five, and eight months post-deployment. We employed latent transition analysis (LTA) to examine Marines' movement across PTSD symptom profiles, determined by latent class analysis (LCA). LCAs revealed a 3-class solution one month pre-deployment, a 4-class solution at five months post-deployment, and a 3-class solution at eight months post-deployment. LTA revealed notable movement between classes over time, which depended chiefly on pre-deployment symptom presentation. Marines who reported few pre-deployment symptoms either maintained these low levels or returned to low levels by eight months. Marines who reported a moderate number of symptoms at pre-deployment had variable outcomes; 50% had reductions by eight months, and those who reported numbing symptoms at five months post-deployment tended to report more symptoms at eight months. Marines who reported more PTSD symptoms prior to deployment retained more symptoms eight months post-deployment. Combat exposure and post-deployment stressor exposure predicted profile transitions. Examining transitions between latent class membership over time revealed prognostic information about Marines' eight-month PTSD outcomes. The extent of pre-deployment PTSD symptoms was particularly informative of likely PTSD outcomes.

The structure of PTSD in active-duty marines across the deployment cycle.

OBJECTIVE: There has been significant debate about the optimal factor structure of posttraumatic stress disorder (PTSD). In military and veteran samples, most available studies have employed self-report measures, assessed PTSD cross-sectionally, used treatment-seeking samples, and assessed symptoms years after deployment. We extend previous studies by comparing the factor structure of clinician-assessed and self-report Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) PTSD in a nontreatment seeking sample at 4 time points spanning the deployment cycle. METHOD: The data source for this study was the Marine Resiliency Study (MRS), a longitudinal study of 4 battalion cohorts of active-duty male Marines deployed to Iraq and Afghanistan between 2008 and 2012. We examined the fourth cohort (N = 892), which was evaluated 1 month predeployment, and 1, 5, and 8 months postdeployment. RESULTS: Confirmatory factor analyses (CFA) revealed that the 5-factor solution best fit the data across all time points, and across both interview and self-report assessments. CONCLUSION: The temporal consistency and convergence demonstrated by our analyses underscores the validity of the 5-factor model among service members exposed to warzone stressors. In particular, the findings suggest that diagnostic criteria for PTSD may benefit from disaggregating hyperarousal symptoms in military samples.

PTSD symptom presentation across the deployment cycle.

BACKGROUND: Symptom-level variation in posttraumatic stress disorder (PTSD) has not yet been examined in the early post-deployment phase, but may be meaningful etiologically, prognostically, and clinically. METHODS: Using latent class analysis (LCA), we examined PTSD symptom heterogeneity in a cohort of participants from the Marine Resiliency Study (MRS), a longitudinal study of combat Marines deployed to Iraq and Afghanistan (N=892). Typologies of PTSD symptom presentation were examined at one month pre-deployment and again one, five, and eight months post-deployment. RESULTS: Heterogeneity in PTSD symptom presentation was evident at each assessment point, and the degree of symptom heterogeneity (i.e., the number of classes identified) differed by time point. Symptom patterns stabilized over time from notable symptom fluctuations during the early post-deployment period to high, medium, and low symptom severity by eight months post-deployment. Hypervigilance and exaggerated startle were frequently endorsed by participants in the initial month post-deployment. Flashbacks, amnesia, and foreshortened future were infrequently endorsed. Greater combat exposure, lifespan trauma, and avoidant coping generally predicted worse outcomes. LIMITATIONS: Data were self-report and may have limited generalizability due to our lack of women and inclusion of only combat Marines. Attrition and re-ranging of data resulted in significant missing data and affected the representativeness of the sample. CONCLUSIONS: Symptom-level variability is highest in the month following deployment and then stabilizes over time. Should post-deployment assessments occur too soon, they may capture common and transient early post-deployment reactions, particularly anxious arousal.

The relationship between course of PTSD symptoms in deployed U.S. Marines and degree of combat exposure.

Large cohort studies suggest that most military personnel experience minimal posttraumatic stress disorder (PTSD) symptoms following warzone deployment, an outcome often labeled resilience. Very low symptom levels, however, may be a marker for low exposure, not resilience, which requires relatively high-magnitude or high-frequency stress exposure as a precondition. We used growth mixture modeling (GMM) to examine the longitudinal course of lifetime PTSD symptoms following combat exposure by disaggregating deployed U.S. Marines into upper, middle, and lower tertiles of combat exposure. All factor models fit the data well; Tucker-Lewis Index (TLI) and comparative fit index (CFI) values ranged from .91 to .97. Three distinct trajectories best explained the data within each tertile. The upper tertile comprised True Resilience (73.2%), New-Onset Symptoms (18.3%), and Pre-existing Symptoms (8.5%) trajectories. The middle tertile also comprised True Resilience (74.5%), New-Onset Symptoms (16.1%), and Pre-existing Symptoms (9.4%) trajectories. The lower tertile comprised Artifactual Resilience (86.3%), Pre-existing Symptoms (7.6%), and New-Onset Symptoms (6.1%) trajectories. True Resilience involved a clinically significant symptom increase followed by a return to baseline, whereas Artifactual Resilience involved consistently low symptoms. Conflating artifactual and true resilience may inaccurately create the expectation of persistently low symptoms regardless of warzone exposure.

Posttraumatic stress in deployed Marines: prospective trajectories of early adaptation.

We examined the course of PTSD symptoms in a cohort of U.S. Marines (N = 867) recruited for the Marine Resiliency Study (MRS) from a single infantry battalion that deployed as a unit for 7 months to Afghanistan during the peak of conflict there. Data were collected via structured interviews and self-report questionnaires 1 month prior to deployment and again at 1, 5, and 8 months postdeployment. Second-order growth mixture modeling was used to disaggregate symptom trajectories; multinomial logistic regression and relative weights analysis were used to assess the role of combat exposure, prior life span trauma, social support, peritraumatic dissociation, and avoidant coping as predictors of trajectory membership. Three trajectories best fit the data: a low-stable symptom course (79%), a new-onset PTSD symptoms course (13%), and a preexisting PTSD symptoms course (8%). Comparison in a separate MRS cohort with lower levels of combat exposure yielded similar results, except for the absence of a new-onset trajectory. In the main cohort, the modal trajectory was a low-stable symptoms course that included a small but clinically meaningful increase in symptoms from predeployment to 1 month postdeployment. We found no trajectory of recovery from more severe symptoms in either cohort, suggesting that the relative change in symptoms from predeployment to 1 month postdeployment might provide the best indicator of first-year course. The best predictors of trajectory membership were peritraumatic dissociation and avoidant coping, suggesting that changes in cognition, perception, and behavior following trauma might be particularly useful indicators of first-year outcomes.

Mowing mitigates bioactivity of neonicotinoid insecticides in nectar of flowering lawn weeds and turfgrass guttation.

Systemic neonicotinoid insecticides are used to control turfgrass insect pests. The authors tested their transference into nectar of flowering lawn weeds or grass guttation droplets, which, if high enough, could be hazardous to bees or other insects that feed on such exudates. The authors applied imidacloprid or clothianidin to turf with white clover, followed by irrigation, and used liquid chromatography-tandem mass spectrometry (LC-MS/MS) to analyze residues in clover blooms that were directly sprayed during application or that formed after the first mowing. Imidacloprid residues in guttation fluid from field-grown creeping bentgrass were assessed similarly. The authors used Orius insidiosus, a small anthrocorid bug that is sensitive to dietary neonicotinoids, as a bioindicator of the exudates' toxicity. Nectar from directly sprayed clover blooms contained 5493 ng/g to 6588 ng/g imidacloprid or 2882 ng/g to 2992 ng/g clothianidin and was acutely toxic to Orius. Residues were 99.4% to 99.8% lower in nectar of blooms formed after mowing, and nontoxic to Orius. Imidacloprid residues in turfgrass guttation averaged 88 ng/g at 1 wk after treatment, causing some intoxication of Orius, but declined to 23 ng/g within 3 wk. Systemic transference of neonicotinoids into white clover nectar and creeping bentgrass guttation appears relatively low and transitory. The hazard to nontarget insects via nectar of flowering weeds in treated lawns can be mitigated by adhering to label precautions and mowing to remove blooms if they are inadvertently sprayed.

Impacts of a neonicotinoid, neonicotinoid-pyrethroid premix, and anthranilic diamide insecticide on four species of turf-inhabiting beneficial insects.

Many turf managers prefer to control foliage- and root-feeding pests with the same application, so-called multiple-targeting, using a single broad-spectrum insecticide or a premix product containing two or more active ingredients. We compared the impact of a neonicotinoid (clothianidin), a premix (clothianidin + bifenthrin), and an anthranilic diamide (chlorantraniliprole), the main insecticide classes used for multiple targeting, on four species of beneficial insects: Harpalus pennsylvanicus, an omnivorous ground beetle, Tiphia vernalis, an ectoparasitoid of scarab grubs, Copidosoma bakeri, a polyembryonic endoparasitoid of black cutworms, and Bombus impatiens, a native bumble bee. Ground beetles that ingested food treated with clothianidin or the premix suffered high mortality, as did C. bakeri wasps exposed to dry residues of those insecticides. Exposure to those insecticides on potted turf cores reduced parasitism by T. vernalis. Bumble bee colonies confined to forage on white clover (Trifolium repens L.) in weedy turf that had been treated with clothianidin or the premix had reduced numbers of workers, honey pots, and immature bees. Premix residues incapacitated H. pennsylvanicus and C. bakeri slightly faster than clothianidin alone, but otherwise we detected no synergistic or additive effects. Chlorantraniliprole had no apparent adverse effects on any of the beneficial species. Implications for controlling turf pests with least disruption of non-target invertebrates are discussed.

Assessing insecticide hazard to bumble bees foraging on flowering weeds in treated lawns.

Maintaining bee-friendly habitats in cities and suburbs can help conserve the vital pollination services of declining bee populations. Despite label precautions not to apply them to blooming plants, neonicotinoids and other residual systemic insecticides may be applied for preventive control of lawn insect pests when spring-flowering weeds are present. Dietary exposure to neonicotinoids adversely affects bees, but the extent of hazard from field usage is controversial. We exposed colonies of the bumble bee Bombus impatiens to turf with blooming white clover that had been treated with clothianidin, a neonicotinoid, or with chlorantraniliprole, the first anthranilic diamide labeled for use on lawns. The sprays were applied at label rate and lightly irrigated. After residues had dried, colonies were confined to forage for six days, and then moved to a non-treated rural site to openly forage and develop. Colonies exposed to clothianidin-treated weedy turf had delayed weight gain and produced no new queens whereas those exposed to chlorantraniliprole-treated plots developed normally compared with controls. Neither bumble bees nor honey bees avoided foraging on treated white clover in open plots. Nectar from clover blooms directly contaminated by spray residues contained 171±44 ppb clothianidin. Notably, neither insecticide adversely impacted bee colonies confined on the treated turf after it had been mown to remove clover blooms present at the time of treatment, and new blooms had formed. Our results validate EPA label precautionary statements not to apply neonicotinoids to blooming nectar-producing plants if bees may visit the treatment area. Whatever systemic hazard through lawn weeds they may pose appears transitory, however, and direct hazard can be mitigated by adhering to label precautions, or if blooms inadvertently are contaminated, by mowing to remove them. Chlorantraniliprole usage on lawns appears non-hazardous to bumble bees.

Comparative impact of an anthranilic diamide and other insecticidal chemistries on beneficial invertebrates and ecosystem services in turfgrass.

BACKGROUND: Chlorantraniliprole, the first anthranilic diamide insecticide labeled for turf, combines strong selective activity against key pests with low vertebrate toxicity. The hypothesis that it is less disruptive to beneficial invertebrates and their ecosystem services than are other prevailing insecticide classes was tested. Plots in golf course settings were treated with chlorantraniliprole, or with a representative nicotinoid (clothianidin), pyethroid (bifenthrin) or a combination (clothianidin-bifenthrin) formulation. Non-target effects were assessed via pitfall traps (epigeal predators), Tullgren funnel extraction (soil microarthropods), hand sorting (earthworms), counting ant mounds and earthworm casts on tees and putting greens, assessing predation on sentinel pest eggs and comparing grass clipping decomposition in treated versus untreated turf. RESULTS: Chlorantraniliprole had little or, in most cases, no impact on predatory or soil invertebrates, predation or decomposition. Each of the other insecticides temporarily reduced abundance and activity of one or more predator groups. Clothianidin and the clothianidin-bifenthrin combination retarded grass clipping decomposition, and the combination suppressed earthworms and casts more than did carbaryl, a toxic standard. CONCLUSION: Chlorantraniliprole is compatible with conservation biocontrol and a good fit for industry initiatives to use relatively less toxic pesticides. One caveat is that its use on golf courses may require targeted management of ant mounds and earthworm casts that are suppressed as a side effect by some less selective insecticides.