Prefrontal 5-HT2a receptor binding index, hopelessness and personality characteristics in attempted suicide

Background: Depression, hopelessness, impaired problem solving capacities and deficient serotonergic functions have been identified as major causes of suicidal behaviour. In general, the relation between biological markers of attempted suicide and psychological functions has been investigated using indirect peripheral markers of, e.g. the serotonergic system. Recently, functional neuroimaging techniques with radioligands allow direct in vivo assessment of the neurobiological status of the central nervous system. Methods: We studied the binding index of serotonin-2a (5-HT2a) receptors in the frontal cortex of attempted suicide patients (n=9) and normal controls (n=13) using [123I]5-I-R91150, a highly selective 5-HT2a receptor ligand. Moreover, we measured personality characteristics (using Cloninger’s Temperament and Character Inventory) and levels of hopelessness (using Beck’s Hopelessness Scale), and studied the association between 5-HT2a receptor binding index, hopelessness and these personality dimensions. Results: When compared to normal controls, attempted suicide patients had a significantly lower binding potential of frontal 5-HT2a receptors, a higher level of hopelessness, a higher score on the temperament dimension harm avoidance and lower scores on the character dimensions self-directedness and cooperativeness. A significant correlation was found between harm avoidance, hopelessness and binding index in the population of patients that attempted suicide. Limitations: The limited number of patients and potential ingestion of psychotropic drugs may influence the results of the study. Conclusions: Lower central serotonergic function, hopelessness and harm avoidance are interrelated phenomena, which may increase the probability of the occurrence of attempted suicide.