This study will examine the use of positron emission tomography (PET) for measuring docosahexaenoic acid (DHA) absorption from the blood into the brain. DHA is a type of fatty acid found in fish and other seafood. It is involved in brain cell activity that underlies the ability to think, move, and respond to the outside world. When the amount of DHA in the brain is low, the brain may not work the same as if there were a normal amount of DHA. If PET can be used successfully to evaluate brain DHA metabolism, this method might be useful for future studies of alcoholism, since brain DHA levels are influenced by alcohol consumption.