Noradrenergic genotype predicts lapses in sustained attention.

Sustained attention is modulated by the neurotransmitter noradrenaline. The balance of dopamine and noradrenaline in the cortex is controlled by the DBH gene. The principal variant in this gene is a C/T change at position -1021, and the T allele at this locus is hypothesised to result in a slower rate of dopamine to noradrenaline conversion than the C allele. Two hundred participants who were genotyped for the DBH C-1021T marker performed the Sustained Attention to Response Task (SART). DBH genotype was found to significantly predict performance; participants with more copies of the T allele made more errors of commission, indicative of lapses in sustained attention. A significant negative correlation was also observed for all participants between errors of commission and mean reaction time. The decrease in noradrenaline occasioned by the T allele may impair sustained attention by reducing participants' ability to remain alert throughout the task and by increasing their susceptibility to distractors.