Hair cortisol may foretell depression among teens
Low or high levels of the stress hormone cortisol in the hair of teenagers may be a potential marker for depression, a new study suggests.
“Early identification of depression is vital as suicide is now the second leading cause of death among adolescents aged 11-17 years in the US,” said lead author Associate Professor Jodi Ford from the Ohio State University-College of Nursing in Columbus, Ohio, US.
In Singapore, suicide is the leading cause of death in those aged 10-29 years, according to the Samaritans of Singapore, with 397 lives lost to suicide in 2018. [https://www.sos.org.sg/learn-about-suicide/quick-facts]
“It’d be really ideal to have an objective measurement as using subjective measures of stress is problematic, particularly with children and teens,” Ford said.
Ford and colleagues measured depressive symptoms via a 9-item short-form of the Center for Epidemiologic Studies-Depression scale in a representative community sample of 432 teenagers aged 11 to 17 years. Cortisol levels were determined using an enzyme immunoassay. [Psychoneuroendocrinology 2019;109:104376]
Cortisol & depression: Significant curvilinear relationship
In the first model, analysis revealed no significant linear relationship between hair cortisol and depressive symptoms (b= –0.036; p=0.13). In the second model, there was a marginally significant linear association (b= –0.044; p=0.06) and a significant curvilinear relationship (b=0.039; p=0.005) between hair cortisol and depressive symptoms. Hair cortisol levels both on the lower and higher end of the sample distribution predicted depressive symptoms.
These findings were consistent with a previous study showing that urinary cortisol at both low and high levels predicted depressive symptoms. [Am J Geriatr Psychiatry 2007; 15: 522–529]
“Our findings open up future research questions and illustrate that the relationship between cortisol levels and depression isn’t necessarily a linear one,” said Ford. “It may be that low cortisol is bad and high cortisol is just as bad and there’s a middle level that is normal.”
She theorized that there could be a blunting of the stress response in some patients, lowering cortisol production or changing how it is processed. “Maybe the body is not using cortisol the way it should in some cases.”
Assessment of hair cortisol creates new possibilities
To date, most studies have looked into cortisol responses using saliva or serum samples, aside from urine. But these methods reflect short-term hormone levels, with daily fluctuations. Collection also presents a burden. Hair cortisol concentrations may be a reliable and valid long-term index of cortisol secretion. [Psychoneuroendocrinology 2018;92:57-65]
Longitudinal research to elucidate the causal relationships between hypothalamic-pituitary adrenal axis dysregulation and depressive symptoms and how cortisol may contribute to these symptoms are warranted. Currently, research merely focused on understanding the link between elevated cortisol and depression, on the premise that cortisol is a driver of inflammation, including neuro-inflammation which brings about depressive symptoms. However, there is heterogeneity in the inflammation-depression link, requiring further studies, said the investigators.