Stress-related peptides in suicide attempters

A suicide attempt is the best known predictor of completed suicide. It has long been assumed that most suicide attempts are the results of stress. The aim of this thesis was to examine some stress related peptides and their relations to the hypothalamic pituitary adrenal (HPA) axis, diagnoses and temperament in a heterogeneous group of suicide attempters shortly after a suicide attempt and at follow up. As compared with healthy controls, the suicide attempters had increased pre- and postdexamethasone cortisol levels. They also had increased plasma delta sleep-inducing peptide (DSIP) and decreased plasma neuropeptide Y (NPY) and corticotrophin releasing hormone (CRH) in plasma. The most deviant DSIP levels were seen in major depressive disorder (MDD) patients and in patients who had attempted suicide previously (repeaters). Repeaters also showed the lowest plasma NPY levels. Furthermore, the results suggested an association between plasma NPY on the one hand and psychasthenia and irritability on the other. CRH concentrations in cerebrospinal fluid (CSF) were continuously low in the patients, whereas CSF somatostatin increased along with clinical improvement. These findings are in contrast with the low DSIP, high NPY and CRH in plasma previously noted in MDD patients by others. They are also in contrast with high CSF CRH levels which normally decrease with recovery from MDD. Our conclusion is that the stress experienced by patients with a recent suicide attempt have alterations in the stress system, which may be somewhat different from the stress system reactions seen in, e.g. general MDD patients.