Brain regional alpha-[C-11]Methyl-(L)-Tryptophan trapping in impulsive subjects with borderline personality disorder

Objective: Neurotransmission of serotonin (or 5-hydroxytryptamine [5-HT]) i s thought to be disturbed in patients exhibiting impulsive behaviors. Howev er, until recently it has not been possible to test this hypothesis in the brains of living humans. Method: Unidirectional trapping of the 5-HT precursor analog alpha-[C-11]me thyl-L-tryptophan (alpha-[C-11]MTrp) has been proposed as an index of 5-HT synthesis capacity. The authors measured brain regional alpha-[C-11]MTrp tr apping with positron emission tomography in medication-free subjects with b orderline personality disorder (N=13) and a healthy comparison group (N=11) . Impulsivity was assessed by using a laboratory measure of behavioral disi nhibition, go/no-go commission errors. Results: Compared to healthy men, the men with borderline personality disor der had significantly lower alpha-[C-11]MTrp trapping in corticostriatal si tes, including the medial frontal gyrus, anterior cingulate gyrus, superior temporal gyrus, and corpus striatum. In the women with borderline personal ity disorder, significantly lower (alpha[C-11]MTrp trapping was seen in few er regions, but in both men and women, negative correlations with impulsivi ty scores were identified in the medial frontal gyrus, anterior cingulate g yrus, temporal gyrus, and striatum. Conclusions: Low 5-HT synthesis capacity in corticostriatal pathways may co ntribute to the development of impulsive behaviors in persons with borderli ne personality disorder.