Biochemical correlates of personality traits in normals: An exploratory study

This study attempted to identify biochemical systems associated with the personality dimensions of Extraversion (E), Neuroticism (N), Psychoticism (P), Sensation Seeking (SS) and Impulsivity (Imp). The subjects were 43 normal volunteers who volunteered to take a battery of psychological tests and allow investigators to obtain samples of blood, urine and cerebrospinal fluid (CSF) for biochemical assessment.Substantial positive correlations were found between CSF norepinephrine (NE), MHPG (the principal metabolite of NE), DBH (an enzyme involved in the production of NE) and plasma MHPG and DBH; all of these are regarded, in some part, as putative indicators of central noradrenergic activity. After partialling out the influences of age, height and weight, a number of significant relationships were found between psychological traits and biochemical variables. Extraversion correlated positively and introversion and neuroticism correlated negatively with CSF Ca. Neuroticism also correlated negatively with plasma MHPG. Ego Strength (inversely related to Neurotic Introversion), P and Disinhibitory SS correlated negatively with CSF cort. General SS correlated negatively with CSF NE and plasma DBH, and these correlations were significant in both males and females, as well as in the total group. The results are consistent with some biological models of personality, but suggest the need for modification in others.