Biological phenotypes associated with individuals at high risk for developing alcohol-related disorders: Part 1.

This article reviews the results of studies concerning particular classes of biological phenotypes that may have relevance for alcohol dependence. Broadly defined, these classes include brain neurotransmitter systems and neuroelectric potentials. Evidence is presented concerning genotypic variation in alcoholics and high-risk relatives suggesting that the etiology of alcoholism and other addictive diseases is mediated in part through suboptimal neurotransmitter functioning. Research opportunities are offered with respect to specific candidate genes that have been cloned from these neurotransmitter systems that could be most fully utilized in family-based genetic analyses. Additional evidence is offered, suggesting that characteristics of particular neuroelectric potentials (e.g. the amplitude of the P300 component of the event-related potential) may provide another dimension of potential markers that could be used to identify children at risk. Finally, methodological considerations specific to high risk studies are discussed. Among these are the need to include a plan for studying more severe cases of alcohol dependence that are relatively uncomplicated by other major psychiatric disorders. Plans for long-term follow-up of children at highest risk for developing the disorder should also be included. Multiple domains of inquiry should not be viewed as "unfocused" but rather as an economical means for utilizing highly characterized samples of individuals meeting rigorous research criteria.