Abstract
CONTEXT: Hypothalamic-pituitary-adrenal (HPA) axis irregularities have been described both in bipolar disorder and suicidal behaviour, but few studies have examined the relationship between suicidal behaviours and cortisol levels in bipolar disorder. OBJECTIVE: We compared HPA axis activity in bipolar I (BPD I) individuals with and without suicidal ideation and behaviour through multiple measurement of serum and salivary cortisol. DESIGN: Cross-sectional, observational study. SUBJECTS AND METHODS: 75 BPD I patients were assigned into 3 groups (no history of suicidal behaviour, history of suicidal ideation, history of suicide attempt), according to the C-SSRS. Socio-demographical and clinical data was obtained by using MINI 6.0 and a semi-structured questionnaire. Salivary samples were collected using Sarstedt Cortisol Salivette synthetic swab system for two consecutive days at 08:00, 16:00, 23:00 and salivary cortisol concentrations were determined by ELISA technique. A unique 1mg dose of dexamethasone was administered on the first day, at 23:00, after the collection of the saliva sample. Blood was collected on the first day at 8:00 AM and basal morning serum cortisol levels were determined by immunoassay with fluorescence detection. RESULTS: Cortisol parameters in our BPD I sample did not vary significantly in respect to suicidal history. However, patients with a history of suicidal ideation have significantly higher total cortisol outputs than patients with no history of suicidal behaviour in the 18 to 40 age category compared with the above 40 age category. CONCLUSIONS: Total cortisol daily output varies significantly in an age-dependent manner in respect to suicidal thoughts in BPD I individuals.