COGA is a comprehensive study conducted at multiple sites across the United States to detect and map genes that confer a susceptibility for alcohol dependence and related disorders, including dependence on other drugs (e.g., nicotine). The study initially recruited alcohol-dependent people and their family members, thereby obtaining a sample of people at high risk for both alcohol-use disorders (i.e., alcohol abuse and alcohol dependence) and smoking. This sample allows COGA investigators to study the relationship between alcohol dependence and smoking among family members.
