Relationships between CSF neuropeptides and temperament traits in suicide attempters

Depressive disorders have been associated with deviances in the levels of various neuropeptide like immunoreactivities in the cerebrospinal fluid (CSF), and also with specific temperament traits. With the hypothesis that neuropeptides in CSF might be associated with specific temperament traits, we studied a sample of 40 hospitalized suicide attempters. They all filled in the Eysenck Personality Questionnaire (EPQ) in combination with the impulsiveness scale from the Impulsiveness-Venturesomeness-Empathy (IVE) inventory. Corticotropin releasing hormone (CRH), neuropeptide Y (NPY), β-endorphin, gamma-melanocyte stimulating hormone (γ2-MSH), somatostatin, peptide YY and delta-sleep inducing peptide (DSIP) like immuno-reactivities were measured in lumbar CSF. Contrary to our hypotheses, there was no relationship between neuroticism and CRH or NPY. Psychoticism and impulsiveness correlated positively and significantly with γ2-MSH, a peptide associated with increased sympathetic drive. The other neuropeptides showed no significant associations with temperament. The relationship between γ2-MSH and the psychoticism dimension needs to be replicated and studies of healthy subjects and non-suicidal patients would be of interest.