A PhD study evaluating the presence of the stress hormone cortisol in hair, has revealed that hair cortisol is a clear marker of neuropsychiatric conditions, including post-traumatic stress disorder (PTSD).
The study is being conducted by Dr Leigh van den Heuvel of the Department of Psychiatry in Stellenbosch University’s Faculty of Medicine and Health Sciences (FMHS).
“Hair cortisol research has expanded dramatically. It is being studied across many conditions and is turning out to be a useful marker of stress,” explained Van den Heuvel. “Hair sampling is easy and non-invasive. Samples can be stored and give a long-term view of the person’s stress system.”
Van den Heuvel’s PhD study is an ancillary study to the Shared Roots study – a multidisciplinary, case-control study examining cardiovascular disease co-morbidity, as defined by the metabolic syndrome in neuropsychiatric disorders. Prof Soraya Seedat is the principal investigator.
“Shared Roots includes three disease cohorts – schizophrenia, Parkinson’s disease and PTSD with patients and controls within each group with and without metabolic syndrome.
“People with neuropsychiatric disorders have higher rates of cardiovascular disease and other chronic lifestyle disorders. We are trying to identify the factors contributing to the co-morbidity,” Van den Heuvel said.
Cortisol and metabolic syndrome
“Cortisol is the main stress hormone. It is produced whenever we have a stressful experience. My study is looking at cortisol levels in hair samples collected from roughly 450 participants in the Shared Roots study.
“Cortisol was first quantified in hair in 2004. Hair analysis in fields like forensics is well established, but ways have now been found to measure endogenous hormones in hair. We are collaborating with Prof Clemens Kirschbaum’s laboratory in Dresden, Germany, who are world experts in hair neuroendocrine analysis. The samples are analysed with liquid-chromatography tandem mass spectrometry, which quantifies five hormones.”
According to Van den Heuvel the aim is to see whether patients have altered levels of hair cortisol compared to controls and to assess whether metabolic syndrome influences cortisol levels.
“Hair grows at 1 cm a month – so each centimetre represents a month of cortisol secretion,” she explained. “With 3 cm samples we have a three-month window.”
However, because the scalp hair must be longer than 3 cm, the sample is largely limited to females.
Although the analysis is ongoing, Van den Heuvel highlighted some preliminary findings.
“The PTSD patients have significantly higher hair cortisol levels than trauma-exposed controls. Hair cortisol seems to be a clear marker of a dysregulated stress system in PTSD.
“The hair cortisol levels are not significantly different between Parkinson’s disease patients and controls, but the cortisone levels are significantly higher. Cortisone is another hormone in the stress axis.
“Hair cortisol is emerging as a clear marker of neuropsychiatric conditions, but we are not seeing an association with metabolic syndrome,” she continued. “I’m working per cohort now, but to assess for an overall effect of metabolic syndrome across disorders I will group the cohorts and maybe then we will see links with this syndrome.”
According to Van den Heuvel, other secondary aims are being addressed in this study.
“As hair cortisol has not been studied extensively in South Africa before, we have assessed other factors influencing hair cortisol levels in our control sample, including hair-care practices, as well as socio-demographic and behavioural factors.”
The study has also looked at whether cortisol is a biomarker of self-perceived stress and resilience. “We are seeing that people with better stress-coping abilities have lower hair cortisol levels.
This demonstrates the value of adding measures of resilience.
“Hair neuroendocrine analysis is a fairly novel investigation field,” Van den Heuvel concludes.
“There is value in quantifiable, easily interpretable biological markers of the endocrine system. This provides insight into the factors that play a role in brain disorders and, in this study, in cardiovascular disease co-morbidity.
“The hair neuroendocrine data will be used to address future research questions. For instance, we can evaluate the role of the other hormones analysed in the neuropsychiatric disorder and link the data with other analyses performed in Shared Roots, such as neuroimaging, inflammatory markers and genomic analyses.”
‘People with neuropsychiatric disorders have higher rates of cardiovascular disease and other chronic lifestyle disorders. We are trying to identify the factors contributing to the co-morbidity.’ – Dr Leigh van den Heuvel
Photo credit: Damien Schumann