Revisiting shyness and sociability: a preliminary investigation of hormone-brain-behavior relations

Personality Affects Zebrafish Response to Sertraline

Sertraline is widely prescribed to treat anxiety and depression. Sertraline acts by blocking serotonin, norepinephrine, and dopamine transporters systems and has been detected in surface waters globally, where it may impact fish behavior. We classified zebrafish personality on three behavioral axes, boldness, anxiety, and sociability, assigning fish as either high or low in each category. The fish were exposed to nominal concentrations of 0, 5, 50, 500, or 5000 ng/L sertraline (measured concentrations: <10, 21.3, 370, and 2200 ng/L, respectively) to assess changes in boldness, anxiety, and sociability after 7 and 28 days. We also measured shoaling behavior and response to an alarm cue, and determined the gut microbiome of a subset of fish. After 7 days there was no overall effect of sertraline on boldness, but there was an interaction between initial personality and sex, with a stronger impact on females classified as low-boldness personality. Sertraline reduced sociability in all treatments compared with the control, but there was again an interaction between sertraline and initial personality. Fish that were classified as low-sociability responded more strongly to sertraline. After 7 days, fish exposed to a nominal concentration of 5000 ng/L (2200 ng/L measured) showed higher anxiety than controls, with the overall pattern of initial behavior retained. After 28 days, similar patterns were observed, but with higher variation. There was only a weak association between the gut microbiome and personality. Overall, the study highlights the importance of considering initial behavior, which can affect response to pollutants. Our results may also be applicable to human studies and provide a mechanism to explain why different individuals respond differently to the drug. Environ Toxicol Chem 2024;43:132-146. © 2023 SETAC.

Trajectories of behavioral avoidance in real time: Associations with temperament and physiological dysregulation in preschoolers

Although excessive avoidance has been implicated in mental health problems and socioemotional difficulties, relatively little is known about dynamic changes of avoidance behaviors. We used a latent class growth analysis to examine the temporal course of avoidance behaviors in real time and determined whether the derived classes were distinguishable on temperament and physiological markers of regulation and reactivity (N = 153; M_age = 4.20 years). A three-class solution was found and identified a low, medium, and high increasing avoidance group. The high and increasing avoidance group had the highest physiological reactivity (cortisol reactivity) and shyness, and the lowest physiological regulation (i.e., respiratory sinus arrythmia suppression). High and increasing avoidance may therefore be associated with temperamental and physiological indices of risk implicated in maladjustment and highlight the value of data-driven, group-based approaches for examining dynamic patterns of behavior.

Shyness Trajectories across the First Four Decades Predict Mental Health Outcomes

Although childhood shyness is presumed to predict mental health problems in adulthood, no prospective studies have examined these outcomes beyond emerging adulthood. As well, existing studies have been limited by retrospective and cross-sectional designs and/or have examined shyness as a dichotomous construct. The present prospective longitudinal study (N = 160; 55 males, 105 females) examined shyness trajectories from childhood to the fourth decade of life and mental health outcomes. Shyness was assessed using parent- and self-rated measures from childhood to adulthood, once every decade at ages 8, 12-16, 22-26, and 30-35. At age 30-35, participants completed a structured psychiatric interview and an experimental task examining attentional biases to facial emotions. We found 3 trajectories of shyness, including a low-stable trajectory (59.4%), an increasing shy trajectory from adolescence to adulthood (23.1%), and a decreasing shy trajectory from childhood to adulthood (17.5%). Relative to the low-stable trajectory, the increasing, but not the decreasing, trajectory was at higher risk for clinical social anxiety, mood, and substance-use disorders and was hypervigilant to angry faces. We found that the development of emotional problems in adulthood among the increasing shy trajectory might be explained in part by adverse peer and social influences during adolescence. Our findings suggest different pathways for early and later developing shyness and that not all shy children grow up to have psychiatric and emotional problems, nor do they all continue to be shy.

Psychosocial functioning and the cortisol awakening response: Meta-analysis, P-curve analysis, and evaluation of the evidential value in existing studies

Cortisol levels rise immediately after awakening and peak approximately 30-45min thereafter. Psychosocial functioning influences this cortisol awakening response (CAR), but there is considerable heterogeneity in the literature. The current study used p-curve and meta-analysis on 709 findings from 212 studies to test the evidential value and estimate effect sizes of four sets of findings: those associating worse psychosocial functioning with higher or lower cortisol increase relative to the waking period (CARi) and to the output of the waking period (AUCw). All four sets of findings demonstrated evidential value. Psychosocial predictors explained 1%-3.6% of variance in CARi and AUCw responses. Based on these effect sizes, cross-sectional studies assessing CAR would need a minimum sample size of 617-783 to detect true effects with 80% power. Depression was linked to higher AUCw and posttraumatic stress to lower AUCw, whereas inconclusive results were obtained for predictor-specific effects on CARi. Suggestions for future CAR research are discussed.