 - People who are in treatment for substance abuse often feel distress during the withdrawal period and afterward. Some individuals feel distress more acutely than others, and this distress has been linked to poor treatment outcomes and increased risk of relapse in smokers, alcoholics, and cocaine- and heroin-dependent individuals. More research is needed on the effects of distress on the brain, particularly in individuals who are seeking treatment for substance abuse. Researchers are interested in using functional magnetic resonance imaging fMRI scanning to study distress tolerance in both substance users seeking treatment and healthy non-drug-using volunteers. 