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Diana P. Prata, PhD; Andrea Mechelli, PhD; Marco M. Picchioni, MD; Cynthia H. Y. Fu, MD, PhD; Timothea Toulopoulou, PhD; Elvira Bramon, MD, PhD; Muriel Walshe, PhD; Robin M. Murray, MD, PhD; David A. Collier, PhD; Philip McGuire, MD, PhD

Arch Gen Psychiatry. 2009;66(11):1162-1172.

Context  The dopamine transporter plays a key role in the regulation of central dopaminergic transmission, which modulates cognitive processing. Disrupted dopamine function and impaired executive processing are robust features of schizophrenia.

Objective  To examine the effect of a polymorphism in the dopamine transporter gene (the variable number of tandem repeats in the 3' untranslated region) on brain function during executive processing in healthy volunteers and patients with schizophrenia. We hypothesized that this variation would have a different effect on prefrontal and striatal activation in schizophrenia, reflecting altered dopamine function.

Design  Case-control study.

Setting  Psychiatric research center.

Participants  Eighty-five subjects, comprising 44 healthy volunteers (18 who were 9-repeat carriers and 26 who were 10-repeat homozygotes) and 41 patients with DSM-IV schizophrenia (18 who were 9-repeat carriers and 23 who were 10-repeat homozygotes).

Main Outcome Measures  Regional brain activation during word generation relative to repetition in an overt verbal fluency task measured by functional magnetic resonance imaging. Main effects of genotype and diagnosis on activation and their interaction were estimated with analysis of variance in SPM5.

Results  Irrespective of diagnosis, the 10-repeat allele was associated with greater activation than the 9-repeat allele in the left anterior insula and right caudate nucleus. Trends for the same effect in the right insula and for greater deactivation in the rostral anterior cingulate cortex were also detected. There were diagnosis x genotype interactions in the left middle frontal gyrus and left nucleus accumbens, where the 9-repeat allele was associated with greater activation than the 10-repeat allele in patients but not controls.

Conclusions  Insular, cingulate, and striatal function during an executive task is normally modulated by variation in the dopamine transporter gene. Its effect on activation in the dorsolateral prefrontal cortex and ventral striatum is altered in patients with schizophrenia. This may reflect altered dopamine function in these regions in schizophrenia.

Author Affiliations: Division of Psychological Medicine and Psychiatry (all authors), Social, Genetic, and Developmental Psychiatry Centre (Drs Prata and Collier), Department of Psychology (Dr Mechelli), and St Andrew's Academic Centre (Dr Picchioni), Institute of Psychiatry, King's College London, London, England.

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