PROLONGED P300 LATENCY IN A NEUROPSYCHIATRIC POPULATION WITH THE D-2 DOPAMINE-RECEPTOR A1 ALLELE

The role of the dopaminergic system in P300 has been implicated and pr evious studies have suggested the presence of a heritable component in the genesis of P300 or P3, a late positive component of the event-rel ated potential. In the present investigation, 155 Caucasian male and f emale diagnosed neuropsychiatrically-ill patients with and without com orbid drug and alcohol abuse/dependence were genotyped for the presenc e or absence of the Al allele of the D2 dopamine receptor gene (DRD2). The relationship of the Al and A2 alleles to P3 amplitude and latency was also determined. The results showed no significant difference in P3 amplitude between all groups studied with Al and A2 allele carriers , However, we now report prolonged P3 latency in neuropsychiatrically- ill patients (with or without polysubstance abuse) with those carrying two copies of the Al allele (homozygote) of the DRD2 gene (quadratic trend, p = 0.01). Moreover, the age-adjusted mean P3 latency in the D( 2)A2/A2 allele group was 327.8 +/ 3.08 ms compared by ANOVA, to 360.04 +/- 4.86 ms in the D(2)A1/A1 group. Our work suggests an association of polymorphisms of the DRD2 gene and a biological marker previously i ndicated to have predictive value in vulnerability to substance abuse.