Pharmacogenetics of Alcohol: Treatment Implications

Alcohol has multiple pharmacological effects, though which of these effects relate to the risk of alcohol dependence is not clear. Animal studies indicate that the neuroactive steroid allopregnanolone is an alcohol-modulated endogenous agonist at GABAA receptors and that genetic variation in steroid 5a-reductase type I gene which generates neuroactive steroids, may moderate alcohol effects. To better define the role of neuroactive steroids we will conduct a laboratory study of non-alcohol dependent drinkers using a 4-session design in which alcohol/placebo beverage is paired with dutasteride/placebo pretreatment. Dutasteride, an inhibitor of both type I and type II 5a-reductase enzymes, blocks the production of 5a-reduced neuroactive steroids. This study will extend our preliminary findings with finasteride by including a) a placebo control for alcohol, b) a more specific inhibitor of both 5a-reductase isoenzymes, c) a larger group of subjects (including both light and heavy drinkers).

Inclusion criteria

• Main Study: Subjects will be healthy volunteers with or without parental history of alcoholism who are 21-45 years old and who have a BMI >18.5 and <32.5. Drinking history: All subjects must report at least one occasion in the prior month of drinking at least 3 drinks on a single day; additionally, LD subjects will be selected if they drink 1-3 drinks, 1-3 times per week (up to 5 drinks per week on average), with no more than one occasion in the past 2 months on which they drank >4 drinks. HD subjects will be selected if they report drinking at least 10 drinks per week, with at least one episode per week of heavy drinking.

Exclusion criteria

• Main Study: Subjects cannot have a current or past DSM-IV diagnosis of alcohol or drug dependence, current or past 24-months diagnosis of alcohol or drug abuse or another major psychiatric disorder, neurological illness, have had a hypersensitivity reaction to dutasteride, evidence of liver dysfunction, currently be using benzodiazepines, other psychotropic medications or medications that are known to influence steroid hormone levels or metabolism or modify the effects of alcohol. Nicotine-dependent subjects will be excluded to avoid the confounding effects of nicotine withdrawal during day-long laboratory sessions. Women are not allowed to participate. Subjects anticipating moving from the area during the period of their planned study participation will be excluded from study entry.