Some people experience the initial effects of alcohol as stimulating and euphoric, while others experience mostly unpleasant sedative effects.  How individuals’ immediate responses to alcohol influence their future drinking behavior has been an active area of scientific research.  One theory holds that people who have a low level of positive response to alcohol and who also are less sensitive to internal cues and warning signs to stop drinking, are more likely to drink to excess and develop alcohol problems.  However, this low-level response theory has been contradicted by studies which suggest that people who drink heavily experience greater alcohol-induced positive effects.  To help resolve these issues, scientists investigated the acute effects of alcohol among nearly 200 young adults who were divided into groups of heavy and light drinkers based on their drinking histories.  In three separate testing sessions, the subjects received one of three drinks: a placebo, a low dose of alcohol, or a high dose of alcohol.  A flavoured drink mix made all of the concoctions taste the same, so none of the subjects knew what they were drinking. For the next three hours, the subjects took breath alcohol tests and answered questions that allowed the researchers to measure a variety of positive and negative effects.  The scientists found that alcohol produced greater stimulant and rewarding responses and lower sedative responses among the heavy drinkers than the light drinkers.  Over a 2-year follow-up period, greater positive effects and lower sedative effects after alcohol consumption predicted increased binge drinking frequency. In turn, greater frequency of binge drinking during follow-up was associated with greater likelihood of meeting diagnostic criteria for alcohol abuse and dependence. The new data could help clinicians identify and prevent unhealthy drinking habits.