Alcohol consumption was derived from questionnaire responses—over 90% of participants said they drank alcohol—and the Alcohol Use Disorders Identification Test (AUDIT-C) clinical screening tool. Three genetic measures related to alcohol use were used as different exposures to study the impact of alcohol quantity, as well as problematic and dependent drinking on dementia risk. Higher genetic risk for all three exposure levels was associated with an increased risk of dementia, with a linear increase in dementia risk the higher the alcohol consumption. A doubling in the genetic risk of alcohol dependency was associated with a 16% increase in dementia risk. Instead, dementia risk steadily increased with more genetically predicted drinking.