Genetic association between the reduced amplitude of the P300 and the allele A1 of the gene which codifies the D2 dopamine receptor (DRD2) as possible biological markers for alcoholism

Introduction. Over the last twenty years much work has been done to study the P300 in alcoholism. A systematically reduced amplitude, both in patients and in populations at risk (children of alcoholics) was found. Besides, studies on twins indicate that the waves of the evoked potentials are under genetic control. Furthermore, advances in molecular genetic techniques have clarified the part played by the allele A1 of the gene which codifies the D2 dopamine receptor in alcoholism. Only in recent years have studies been published relating them and in these they are considered to be risk markers for alcoholism. However, contradictory results have been obtained. Development. The objective of this study is to review part of the literature and find evidence for and against the characteristics observed in the P300 and the possible part played by the DRD2 gene in the aetiology of alcoholism and the relationship between them. At the same time we consider the most relevant theoretical aspects of the role played by dopamine in the central nervous system, since some studies have shown that it is involved in the generation of P300 and reinforcement due to alcohol consumptions. Finally, we discuss the advantages and disadvantages that should be taken into account when considering the low amplitude of P300 and the presence of the A1 allele as diagnostic markers to identify populations at risk and thus avoid appearance of the disorder.