In the U.S., hundreds of thousands of people use the illegal stimulant drug methamphetamine every month. In addition, tens of millions of people consume alcohol. There is a considerable degree of overlap between the methamphetamine-using population and the alcohol-using population. In a study scheduled for publication in 2014 in the journal Drug and Alcohol Dependence, researchers from two U.S. universities explored the impact that alcohol consumption has on typical patterns of methamphetamine use. These researchers concluded that drinking in general, and a practice called binge drinking in particular, tend to lead to increases in methamphetamine intake. Methamphetamine Use The Substance Abuse and Mental Health Services Administration tracks the nationwide frequency of methamphetamine use in the non-homeless, non-incarcerated general population through a project called the National Survey on Drug Use and Health. The most current available figures (gathered for 2012) indicate that about 440,000 people in the mainstream population use\/abuse this powerful drug every month. When figures for an entire year are included, the number of current users rises to roughly 1.2 million. Roughly 133,000 people took methamphetamine for the first time in 2012. The average new user was just shy of his or her 20th birthday. Alcohol Use Over 135 million Americans drink alcohol with some regularity. Monthly consumption rates are above 40 percent for all adult age groups, ranging from the youngest adults (18- to 21-year-olds) all the way to senior citizens. The maximum rate of monthly alcohol intake, 69.2 percent, occurs in people between the ages of 21 and 25. Generally speaking, the rate of drinking drops gradually over the following decades. A similar trend holds true for binge drinking - which involves consuming enough alcohol to get drunk in a couple of hours - as well as for heavy drinking, which involves exceeding the daily or weekly recommendations for moderate alcohol intake. Combined Effects When used in combination, methamphetamine and alcohol produce different effects than they do on their own. For example, people who start using the two substances together typically experience unusually large spikes in their normal heart rates and also report a more intense \u201chigh.\u201d In addition, in the short run, methamphetamine use can make an alcohol consumer feel less intoxicated. Conversely, in the short run, alcohol use can reduce the intensity of the sleep problems commonly associated with methamphetamine intake. Most of the unique effects of the methamphetamine-alcohol combination start to fade relatively quickly with repeated intake. Impact of Drinking In the study slated for publication in Drug and Alcohol Dependence, researchers from the University of Southern California and UCLA assessed the impact of alcohol consumption on habitual patterns of methamphetamine use with the help of 60 people who regularly used the substances in combination. All of these individuals took part in a detailed interview process designed to detect the presence of methamphetamine addiction and also provided information on their alcohol and methamphetamine intake during the month prior to the start of the study. The researchers came to several conclusions after analyzing the data. First, they concluded that, compared to a day on which he or she consumes no alcohol, a methamphetamine user has a roughly 322 percent greater chance of consuming the drug on a day when any amount of alcohol is consumed. The odds rise even higher to 350 percent when a methamphetamine user takes part in binge drinking on a given day. The researchers additionally concluded that binge drinking also increases the odds of same-day methamphetamine consumption in certain indirect ways. The consumption of any amount of alcohol on one day apparently does not increase the odds for methamphetamine consumption on the following day. In addition, binge drinking participation on one day apparently does not increase the odds for meth intake the next day. The researchers concluded that two groups of alcohol-consuming methamphetamine users are most likely to increase their same-day meth intake after binge drinking: people with fairly mild cases of methamphetamine addiction and people with fairly prominent symptoms of alcoholism and\/or alcohol abuse. The study\u2019s authors believe that their findings point toward a relatively stable relationship between alcohol use and a methamphetamine user\u2019s daily level of meth intake. They note the particular impact of binge drinking and call for further research designed to determine more precisely how the passage of time influences same-day methamphetamine and alcohol consumption.