A case-control sample of 1945 phenotyped subjects was selected from the larger COGA sample for genome-wide association studies. Cases had a lifetime diagnosis of AD by DSM-IV criteria. Controls reported consuming alcohol but did not have a diagnosis of AD or alcohol abuse by any of the diagnostic criteria assessed by SSAGA and did not meet diagnostic criteria for dependence on cocaine, marijuana, opioids, sedatives, or stimulants. Controls could not share a known common ancestor with a case and were preferentially selected to be above the age of 25 years.
