Platelet Serotonin Level and Impulsivity in Human Self-destructive Behavior: A Biological and Psychological Study

CONTEXT: Suicide is a disease and a global public health problem. Suicidology has come to become a topic of study for intervention and research. The serotonin (5-hydroxytryptamine [5HT]) system has remained a prime area of investigation. The neurons and platelets display structural and functional similarities. Ninety-nine percent of 5HT is contained in platelets, which shares similar 5HT uptake and release mechanisms with 5HT neurons. AIMS: This study aims to study human self-destructive behavior (HSDB). OBJECTIVES: Exploring the biological (serotonin levels in platelets) and psychological aspects (impulsivity) of attempted suicide or HSDB. SETTINGS AND DESIGN: Thirty-one patients, above the age of 18 years, with a recent history of HSDB, were studied and given an International Classification of Diseases-10 diagnosis, after a detailed interview. SUBJECTS AND METHODS: For the platelet 5HT estimation, blood samples were collected, and enzyme immunometric assay carried out. Detailed assessment of the impulsivity was done by the 25-item structured diagnostic interview for borderlines by Zanarini et al. STATISTICAL ANALYSIS USED: We obtained both categorical and continuous data. Chi-square test, Fisher's test, Student's t-test, and Pearson's product moment correlation were used. RESULTS: Female subjects outnumbered males by 2:1. Major depression, adjustment disorder, personality disorder were predominant diagnoses. The mean platelet serotonin concentration for males = 57.3 ng/ml, that of females = 56.05 ng/ml (P > 0.05). Platelet 5HT levels were found to be negatively correlated with impulsivity scores (P < 0.05). CONCLUSIONS: Platelet serotonin levels in our study sample were quite low when compared with those reported in published literature. Low serotonin levels were inversely related to impulsivity, but only in males.