Abstract Background Hair cortisol is an emerging biomarker of chronic stress. However, the psychological and physiological aspects of chronic stress that are reflected in hair cortisol concentration (HCC) have not been fully determined. Since physiological responses to stress do not always align with how stress is perceived, we conducted this study to evaluate whether HCC correlates with neuroendocrine stress indicators or stress perceptions. Objective This study aimed to evaluate whether subjective (Perceived Stress Scale and Connor-Davidson Resilience Scale) and objective (plasma cortisol/dehydroepiandrosterone-sulfate [DHEA-S] and cortisol/high-sensitivity C-reactive protein) determinants of stress and resilience correlate with HCC. Methods In this cross-sectional pilot validity study, scatter plots and Spearman correlation coefficients were used to measure the direction and magnitude of the relationship between stress and resilience measures among 51 predominantly male participants. In a subset (n=24), we performed a step-wise regression modeling approach to isolate the association of perceived and somatic stress on hair cortisol. Results Bivariate correlations showed a weak inverse association of HCC with Perceived Stress Scale (Spearman correlation ρ=−0.14, P=.52) and a stronger positive association with somatic neuroendocrine stress indices cortisol/DHEA-S (ρ=0.24, P=.25) and cortisol/high-sensitivity C-reactive protein (ρ=0.21, P=.35). In linear regression models, HCC showed the strongest association with cortisol/DHEA-S (r2=0.10, P=.13, 1.01β 1.01, 95% CI 0.99‐1.01). This relationship remained when age, gender, hair washing frequency, hair dye or bleach use, diabetes mellitus, obesity, cardiovascular disease, anxiety, medication use, and endocrine disorders were considered. Conclusions Our results do not indicate a statistically significant association (at the P<.05 threshold) between HCC and stress perception or somatic measures of neuroendocrine response. Methods In this cross-sectional pilot validity study, scatter plots and Spearman correlation coefficients were used to measure the direction and magnitude of the relationship between stress and resilience measures among 51 predominantly male participants. In a subset (n=24), we performed a step-wise regression modeling approach to isolate the association of perceived and somatic stress on hair cortisol. Results Bivariate correlations showed a weak inverse association of HCC with Perceived Stress Scale (Spearman correlation ρ=−0.14, P =.52) and a stronger positive association with somatic neuroendocrine stress indices cortisol/DHEA-S (ρ=0.24, P =.25) and cortisol/high-sensitivity C-reactive protein (ρ=0.21, P =.35). In linear regression models, HCC showed the strongest association with cortisol/DHEA-S ( r 2 =0.10, P =.13, 1.01 β 1.01, 95% CI Research has identified age, sex, hair washing frequency, hair treatment, and oral contraceptive use as relevant covariates [ 12 ]. Health conditions and other medications can also influence HCC [ 10 ]. The second is understanding the stress-related determinants of HCC [ 12 ]. Thus far, the correlation between validated measures of perceived stress and HCC has been inconsistent [ 9 , 12 , 13 ]. Psychological resilience has been shown to moderate the indirect association of perceived stress with illness severity via HCC [ 14 ] but little research is available on the relationship between HCC and physiologic stress indices. During the nursing intake process, patients were invited to participate, and written informed consent ( Multimedia Appendix 1 ) was obtained, and the nature of the procedures was fully explained. Psychological Stress Measures The PSS 10-item designed by Cohen et al [ 24 ] was used for assessing perceived stress over the past month. This psychometrically validated 10-item self-reported questionnaire is the most widely used psychological instrument for measuring the degree to which an individual appraises situations in one’s life as stressful. Each item is forward or reverse scored from 0 to 4 based on the experienced frequency of each item. We used scatter plots and Spearman correlation coefficients (ρ) to measure the direction and magnitude of the relationship between stress and resilience measures. To isolate the impact of perceived and somatic stress on HCC from the impact of other factors impacting HCC, we used a step-wise regression modeling approach. As a first step, we used simple linear regression modeling of each perceived and somatic neuroendocrine stress construct regressed on HCC to determine which variables had the strongest independent association. Next, we used multivariate regression modeling to calculate fully adjusted associates controlling for factors impacting HCC. j DHEA(S): collective term for dehydroepiandrosterone and dehydroepiandrosterone-sulfate. k hs-CRP: high-sensitivity C-reactive protein. Figure 1. Correlation between log hair cortisol concentration and predictors. Log transformed hair cortisol concentration does not show a linear relationship with (A) Perceived Stress Scale-10 score but does show a weak to moderate linear correlation with (B) log transformed cortisol/DHEA(S) ratio. DHEA(S): collective term for dehydroepiandrosterone and dehydroepiandrosterone-sulfate; HCC: hair cortisol concentration; PSS: Perceived Stress Scale. We did find several weak to moderate nonsignificant correlations, with a stronger relationship between HCC and other somatic indices of stress rather than with perceived stress. Interestingly, HCC showed the strongest positive association with cortisol/DHEA(S). While we hypothesized that somatic stress indicators would show a stronger association with HCC, our results did not support a significant difference. Of interest, we found weak evidence that neuroendocrine indices that include the modulating effect of resilience factors may complement HCC as a clinical tool for measuring chronic stress burden.

Personality and demographic variables related to individual responsiveness to diving stress. Thirty U.S. Navy divers were tested for 4 personality and 2 demographic variables. They subsequently were exposed to the stress of being pressurized in a small diving chamber for several hours. Stress responsiveness to this condition was assessed using 3 physiologic and 4 subjective emotionality measures before and after the dive. These physiologic and emotionality measures were factor analyzed and correlated with personality and demographic variables. Difference scores among the physiologic and emotionality measures, indicating responsiveness to stress, correlated significantly with education, diving experience, internality-externality, disinhibition, and socialization. These data indicate that measures of achievement (i.e., diving experience and education), perceived control, sensation seeking, and social adjustment are useful in accounting for individual differences in acute emotional and physiologic responsiveness to stressful diving conditions. Published in Undersea biomedical research (1987)

Stress is increasingly recognized as a complex, multidimensional phenomenon shaped by interacting biological, psychological, and social factors, and it has been linked to numerous physical conditions. Several inflammatory and oxidative stress markers have been correlated with perceived stress. However, the combined association of biochemical variables, inflammatory and oxidative stress biomarkers, and DNA methylation with perceived stress has not yet been examined in the Mexican population. Therefore, the objective of this study was to determine such an association in a sample of non-representative Mexican adult individuals. A total of 157 individuals were included, of whom 83 (53%) were women. Women showed higher values of stress than men. In the bivariate correlations, perceived stress correlated negatively with sleep quality, age, total cholesterol, monthly earnings and waist-to-hip ratio and positively with morbidity count, leucocytes and platelets. In the multivariable analyses, additional variables were associated with perceived stress, including a positive correlation with IL-1β in the total sample, a positive correlation with 8-isoprostane in the women's sample, and a negative correlation with this molecule in the men's sample. Similarly, perceived stress correlated positively with DNA global methylation in the men's sample and negatively with this variable in the women's sample. In conclusion, perceived stress showed correlations with many variables, including sociodemographic and behavioral ones, such as sex, age and sleep quality; biochemical variables, including serum lipids, platelets and leukocytes; and inflammation (IL-1β), oxidative stress (8-isoprostane) and DNA methylation (global DNA methylation) biomarkers, some of them showing opposite correlations in each sex.