Summary: Hair cortisol measured from a small hair sample may help identify adolescents at risk for depression. In a study of 432 youths, both higher and lower hair cortisol levels were associated with greater depressive symptoms, suggesting a non-linear relationship between long-term cortisol exposure and mental health.
Source: Ohio State University
Researchers say a simple hair test could one day aid in identifying depression and tracking treatment response in young people.
A recent study led by Jodi Ford, an associate professor of nursing at The Ohio State University, explored whether cortisol concentrations in hair predict depressive symptoms in adolescents. Cortisol, a hormone released in response to stress, can be measured in hair to provide a retrospective indicator of average cortisol exposure over months. The study, published in Psychoneuroendocrinology, found a surprising U-shaped pattern: both unusually low and unusually high hair cortisol levels were linked to greater depressive symptoms.
Most prior research has measured cortisol in saliva or blood and produced mixed results when trying to link cortisol to depression. By using hair cortisol to capture longer-term hormone levels, this study adds new evidence that the relationship between cortisol and depression in youth is complex rather than strictly linear.
“The relationship between cortisol and depression doesn’t appear to be one-directional,” said Ford. “There may be a middle range of cortisol that is healthiest, while both blunted and elevated cortisol patterns are associated with higher depressive symptoms. More research is needed to understand the biological mechanisms behind this.”
The study also highlighted the powerful protective effect of family support. Adolescents who reported feeling more supported at home exhibited substantially fewer depressive symptoms, reinforcing the important role parents and caregivers play during adolescence.
The research sample included 432 adolescents, ages 11 to 17, drawn from the larger Adolescent Health and Development in Context study. Depressive symptoms were assessed with a nine-item short form of a standard depression scale; participants answered questions about feelings such as failure, loneliness, and social difficulties. Hair samples were taken from the posterior vertex region of the scalp, and in most cases a 3-centimeter segment was analyzed—reflecting cortisol accumulation over approximately three months.
After accounting for factors that might influence both cortisol and mood, the researchers found that the association between hair cortisol and depressive symptoms was best described as curvilinear: youths with either low or high hair cortisol were more likely to report depressive symptoms than those with mid-range cortisol values. Statistically, this produced a U-shaped relationship in their analyses.
Depression among young people has been rising. According to 2016 data cited in the study, nearly one in eight adolescents experienced a major depressive episode, and suicide is the second leading cause of death in this age group. Because adolescents often have difficulty describing their emotional experiences, objective biomarkers could support earlier detection and intervention.
“An objective measure would be especially helpful because self-reported stress can be unreliable in children and teens,” Ford noted.
Hair testing is relatively straightforward and inexpensive in comparison to many clinical tests—roughly on the order of about $35 per assay. However, Ford cautions that routine clinical use is premature. Researchers must first establish reliable reference ranges for normal and abnormal hair cortisol in adolescents and better understand how cortisol patterns evolve with treatment, stress exposure, and developmental changes.
Looking ahead, Ford plans to conduct larger and longer longitudinal studies to track hair cortisol and depressive symptoms over time. Such research could determine whether hair cortisol can function not only as a screening biomarker but also as a tool to monitor treatment response or emerging risk for worsening depression and suicidal behavior.
Samantha Boch of Nationwide Children’s Hospital and Christopher R. Browning, a sociology professor at Ohio State and co-leader of the larger longitudinal study, are co-authors on the paper. The research was supported by the National Institutes of Health.
Source:
Ohio State University
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Jodi Ford – Ohio State University
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Image credited to Ohio State University.
Original Research: Closed access. Title: “Hair cortisol and depressive symptoms in youth: An investigation of curvilinear relationships.” Authors: Jodi L. Ford, Samantha J. Boch, Christopher R. Browning. Journal: Psychoneuroendocrinology. DOI information available in the original publication.
Abstract (condensed)
Background: As youth depression rises, biomarkers that predict depressive symptoms are of growing interest. Hair cortisol provides a retrospective, longer-term measure of mean cortisol. This study examined whether hair cortisol predicts depressive symptoms in adolescents, including potential nonlinear associations.
Methods: A representative sample of 432 adolescents (ages 11–17) completed a nine-item depression inventory. Hair samples (typically 3 cm) were processed and assayed for cortisol. Values were log-transformed for analysis.
Results: Multivariable regression found no simple linear association; however, models that tested curvature revealed a significant curvilinear (U-shaped) relationship, indicating elevated depressive symptoms at low and high cortisol levels.
Conclusions: The findings emphasize the importance of exploring nonlinear links between hypothalamic-pituitary-adrenal axis activity and depressive symptoms. Longitudinal, mechanistic studies are needed to clarify causal pathways and to determine whether hair cortisol can meaningfully inform clinical care for adolescents.