Associations between hair cortisol and blood pressure: a systematic review and meta-analysis

Objective:Stress is widely considered to be a risk factor for high blood pressure (BP), but evidence on the associations between biomarkers of chronic stress and BP is inconsistent. This systematic review and meta-analysis assessed the current state of the science on relationships between measures of cortisol concentration reflecting chronic stress exposure [hair cortisol concentration (HCC), nail cortisol concentration)] and BP.Methods:PubMed, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Cochrane Library, and Embase were searched. Random effects models were used to assess the pooled effect size. Exploratory moderation analysis was performed.Results:Out of 34 014 identified, 16 articles met eligibility criteria and were included in the review, while 14 were included in the meta-analysis. No articles were reported on the association between nail cortisol concentration and BP. Small, positive associations were observed between HCC and SBP [r = 0.19 (95% confidence interval (CI): 0.08-0.29)] and HCC and DBP [r = 0.13 (95% CI: 0.04-0.22)]. Cortisol analysis method was identified as a significant moderator of the association between HCC and DBP. HCC was largely, positively associated with hypertension status [odds ratio = 3.23 (95% CI: 2.55-4.09), P Conclusions:Current evidence suggests that higher HCC may be associated with elevated BP and a potential risk factor for hypertension. However, results should be interpreted with caution because HCC can be affected by hair color, hair care products, and analytic methods. Given the limitations of studies included in this review, further research is needed.