background Previous research has shown a relationship between the stress hormone cortisol and bipolar disorder. The level of cortisol exposure is usually examined by means of measurements that provide a snapshot of cortisol exposure or by means of dynamic testing. Recently, a new technique has been introduced which can measure, retrospectively, the cortisol level in scalp hair over longer periods of time.
aim To provide insight into various methods used in psychiatry for measuring the hypothalamus-pituitary-adrenal (hpa)-axis activity and also to highlight recent research into measurements of cortisol in scalp hair of patients with bipolar disorder.
method We give a brief overview of the literature relating to hpa-axis testing in psychiatric patients. As a result of our recent studies with 100 patients suffering from bipolar disorder, we are now able to determine the levels of cortisol in scalp hair.
results Tests that measure hpa activity can be divided into three categories: point measurements, stimulation tests and inhibition tests. In our recent study of bipolar patients we found that a raised level of cortisol in scalp hair was related to a later onset of bipolar disorder (in patients over 30) or to multiple psychiatric diagnoses. Lower levels of cortisol level in scalp hair of bipolar patients were observed in bipolar patients with comorbid panic disorder.
conclusion The use of hair analysis to measure mean cortisol levels over long periods seems to give added value to the hpa-axis tests currently used for measuring cortisol exposure. The technique may make it easier to differentiate between various subtypes of bipolar disorder.