Prior Stressful Events Research Articles

Thermal fitness costs and benefits of developmental acclimation in fall armyworm

Global increases in mean temperatures and changes in precipitation patterns due to climate change, coupled with anthropogenic pathways, have intensified biological invasions of pest insects. Continuous exposure to bouts of acute and chronic heat and fasting stresses (during e.g., droughts) might improve pest performance under recurring stresses, therefore enhancing/reducing fitness within- or across- life stages (i.e., ‘carry-over’ effects). Here, we examined developmental acclimation effects in the invasive fall army worm Spodoptera frugiperda — a highly invasive economic insect pest of cereal crops, particularly maize — using standardized heat tolerance metrics. Specifically, we assessed the effects of acute (3h) and chronic (3 days) heat treatments (at 32°C, 35°C, 38°C), as well as fasting (48h), on 3rd instar larvae, and tested fitness traits (critical thermal maxima [CTmax] and heat knockdown time [HKDT]) at a later life stage (4th/5th larval instar). Acclimation to heat stress and fasting had significant fitness costs (lower CTmax) across majority of treatments. However, both heat and fasting acclimation improved HKDT (except for 35 and 38°C [acute acclimation] and 35°C [chronic acclimation]). Our results suggest context-specific developmental acclimation costs and benefits in S. frugiperda. In particular, heat and fasting acclimation potentially have fitness costs and benefits for subsequent developmental stages facing high temperature stress. These results are important for estimating the effects of prior stressful events on future survival of invasive insect species and may be significant in predicting pest population dynamics under changing environmental conditions.

Post-traumatic Growth and Resilience in Adolescents in Puerto Rico Post-hurricane Maria

Background/Rationale: Hurricane Maria and the COVID-19 pandemic have greatly impacted the lives of adolescents in Puerto Rico. Understanding how individuals respond to stress can elucidate strategies used to cope and grow from impactful life events (ILE) while minimizing adverse mental health consequences. This expands on work with medical students in Fukushima post-3/11. Hypothesis or Research Question: Adolescents who utilize more resilience behaviors will experience more post-traumatic growth. Adolescents who demonstrate posttraumatic growth from a previous event will experience less COVID-related stress. Study Design/Methods: Students were anonymously surveyed and responded to the Davidson-Trauma Scale (DTS), Post-Traumatic Growth Inventory (PTGI), Connor-Davidson Resilience Scale-10 (CDRS-10), Resilient Behavior Scale (RBS), and questions specific to COVID-19 and Hurricane Maria. Data was analyzed by examining correlations between scales and between scales and questions specific to COVID-19 and natural disasters. Results: Most students indicated the COVID-19 pandemic as their most impactful life event (44%) (Figure 1). The RBS and CDRS-10 were positively correlated with each other (r = .679, p = .002). The PTGI was positively correlated with the RBS (r = .878, p Conclusions/Future Plans: Our results indicate adolescents’ resilient behaviors, not resiliency per se, were associated with post-traumatic growth since only RBS was correlated with PTG. Additionally, undergoing prior stressful events appears to mitigate distress from future stressors. Finally, experiencing an ILE alongside others appears to lead to greater PTG suggesting an important role for social connection. The social isolation of COVID-19 may have diffused the potential to find something positive in the event even in those experiencing PTG.

Oxytocin and the stress buffering effect of social company: a genetic study in daily life.

Social relationships are a crucial determinant of both mental and physical health. This effect is partly due to social buffering of stress. Animal studies suggest that social buffering is mediated via the oxytocin system, while studies in humans are sparse and limited by the low ecological validity of laboratory settings. In the present study, participants (N = 326) completed smartphone questionnaires four times a day over 4 to 5 days, measuring stressors, negative affect, and social context to assess social buffering. We found that under stress, participants reported a higher need for social company. Further, the impact of prior stressful events on momentary negative affect was attenuated by the perceived pleasantness of current social company. This social buffering effect was moderated by haplotypes of the oxytocin receptor gene, based on two well-described single nucleotide polymorphisms (rs2268498, rs53576). Effects were robust when controlling for gender and age, applying different data quality criteria, and even apparent in genotype-based analyses. Our findings demonstrate that social buffering and its modulation by oxytocin system characteristics have implications for life as lived outside the laboratory.

Endogenous Opioids Released During Non-Nociceptive Environmental Stress Induce Latent Pain Sensitization Via a NMDA-Dependent Process

Although stress induces analgesia, there is evidence that stressful events may exacerbate pain syndromes. Here, we studied the effects of 1 to 3 prestressful events (days 0, 2, and 7), such as non-nociceptive environmental stress, on inflammatory hyperalgesia induced by a carrageenan injection (day 14) in 1 rat hind paw. Changes in nociceptive threshold were evaluated by the paw pressure vocalization test. The higher the number of stress sessions presented to the rats, the greater was the inflammatory hyperalgesia. Blockade of opioid receptors by naltrexone before each stress inhibited stress-induced analgesia and suppressed the exaggerated inflammatory hyperalgesia. Stressed versus nonstressed animals could be discriminated by their response to a fentanyl ultra-low dose (fULD), that produced hyperalgesia or analgesia, respectively. This pharmacological test permitted the prediction of the pain vulnerability level of prestressed rats because fULD analgesic or hyperalgesic indices were positively correlated with inflammatory hyperalgesic indices (r 2 = .84). In prestressed rats, fULD-induced hyperalgesia and the exaggerated inflammatory hyperalgesia were prevented NMDA receptor antagonists. This study provides some preclinical evidence that pain intensity is not only the result of nociceptive input level but is also dependent on the individual history, especially prior life stress events associated with endogenous opioid release. Perspective Based on these preclinical data, it would be of clinical interest to evaluate whether prior stressful events may also affect further pain sensation in humans. Moreover, this preclinical model could be a good tool for evaluating new therapeutic strategies for relieving pain hypersensitivity.

Diminished cortisol responses to psychosocial stress associated with lifetime adverse events: A study among healthy young subjects

Animal and human studies have found that prior stressful events can result in an altered reactivity in the HPA axis. The aim of the present study was to investigate the role of adverse events in childhood on cortisol reactivity to psychosocial stress in young healthy subjects (n=80). Salivary cortisol levels were measured before, during and after exposure to a psychosocial stress task in healthy men and women with high (n=33) and low (n=47) exposure to adverse childhood events. A significant blunted cortisol response was found in individuals with a history of adverse events compared to individuals with no adverse life events, with no differences in baseline cortisol levels. This finding appeared to be primarily driven by men. The groups did not differ on any other physiological or subjective stress measure, including heart rate, blood pressure, and subjective tension. These findings suggest that, at least in healthy young males, adverse childhood events are associated with changes in HPA-axis functioning. Longitudinal studies are needed to investigate whether the blunted cortisol response is a risk factor in the etiology of psychiatric disorders or rather reflects resiliency with regard to the development of psychopathology.

Stressful events, mastery, and depression: An evaluation of crisis theory

The effect of prior stressful events and mastery on psychological distress during and following a threat to life was examined, and three competing models concerning the effect of prior stressful events on reactions to severe life crisis were compared. The stressful events model suggests that prior stressful events increase vulnerability to new threatening events. The traditional crisis model suggests no such effect of prior stressful events on crisis reaction due to the overwhelming effect of the crisis at hand. A facilitator model predicts that prior events decrease vulnerability to crisis due to a “practice effect.” Fifty-five Israeli women (not found to have cancer) were studied just prior to and 3 months following biopsy for suspected cancer. Those with greater prior stressful events were significantly more state depressed at both times than those experiencing fewer events, supporting the stressful events model. It was also found that mastery moderated the extent to which women were depressed and the period of time they remained depressed. However, mastery did not limit the stressful life event — depression relationship. Implications for research and intervention are discussed.