An exploratory study linked selected DRD2 variants to stopping performance and found genotype-dependent responses to amphetamine. It did not validate a genetic test that can predict a particular person’s inhibition after taking the drug.
Hamidovic and colleagues studied 93 healthy volunteers, comparing 12 dopamine-D2-receptor gene variants with stop-task performance and self-reported impulsivity. Participants received placebo and d-amphetamine in randomized order. The analysis first considered drug-free performance and personality, then examined drug-related task and mood responses. Genetic associations were observational even though the drug conditions were experimentally controlled.
Two variants and a related haplotype were associated with better drug-free stop-task performance and lower impulsivity ratings. At rs12364283, amphetamine shortened stop reaction time in the A/A group but lengthened it in the combined alternative-genotype group. Mood effects were not significantly related to the tested genotypes. The finding was therefore not a general association with every subjective or behavioral drug response.
The study was exploratory and involved a relatively homogeneous, largely college-student population. Baseline group differences, small genotype subgroups and multiple comparisons complicate interpretation. A genotype association does not establish deterministic behavior, and the same marker can relate differently to baseline performance and change after a drug. The results cannot identify ingestion, establish a concentration or explain an individual’s conduct at a prior event. Replication and prospective prediction are necessary before clinical or forensic use. The paper supports investigating variation in response rather than assigning a genetic label of impaired inhibition.
See a different gene and a different attention outcome.