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

BACKGROUND: 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. AIMS: To assess whether neuroticism predicts mood change in response to ATD in healthy volunteers. METHOD: 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. RESULTS: 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. CONCLUSIONS: Neuroticism moderates aspects of cognitive function, but in this study it was not strongly related with mood change via serotonin.