Neuroticism as a predictor of mood change: the effects of tryptophan depletion.

Abstract

Acute tryptophan depletion (ATD) results in a transient lowering of mood in patients recovered from depression and in healthy volunteers with a family history of affective disorders. The personality trait of neuroticism is strongly associated with depression. To assess whether neuroticism predicts mood change in response to ATD in healthy volunteers. Healthy volunteers who scored at the top and bottom fifth percentiles of neuroticism scores (17 and 15 respectively) were selected. In a double-blind, crossover study they received a tryptophan-free or a control drink. Mood and cognition were assessed. Neuroticism did not predict the amount of mood change following ATD but did moderate performance on the verbal fluency test. A family history of affective disorder (n=5) predicted mood change but not cognitive function following ATD. Neuroticism moderates aspects of cognitive function, but in this study it was not strongly related with mood change via serotonin.