How do you know if someone you care about is just someone who likes to drink, or if they have sunk deep into the morass of alcoholism? How do you know when one is turning into the other? And, perhaps the hardest question, how do you help them?

According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA), 7.1 percent, or 17 million U.S. adults suffer from "alcohol use disorder"—the medical description of alcoholism. Symptoms of alcohol abuse include withdrawal—more intrusive and severe hangovers eventually become potentially fatal delirium tremens—and an increasing inability to control one’s drinking, even after trying to cut down.

Yet, how do we differentiate between self-described “drinkers” and people with serious alcohol problems? As it turns out, the distinction is primarily one of degree. When it comes to substance abuse, alcohol can quickly transform from an enabler of "bad" collegiate behavior, into the controlling force in one’s life.

Why people may be predisposed to be alcoholics.

Some alcoholics may begin as college drinkers. Countless public health problems have been attributed to college binge drinking, including alcohol poisoning, sexual assault, and drunk driving. But research into the connection (PDF) between college binge drinking and alcoholism remains inconclusive; while most can certainly bring to mind college friends who were more often than not inebriated, we would likely not describe all of those same people as alcoholics today.

"Not all alcohol abusers develop alcohol dependence or alcoholism, but it is a major risk factor," the National Council on Alcoholism and Drug Dependence (NCADD) explains. "Sometimes alcoholism develops suddenly in response to a genetic predisposition from a family history of alcoholism or due to a stressful change, such as a breakup, retirement, or another loss."

That's not the only way that alcoholism can begin; the NCADD also states that your risk for slipping slowly into alcoholism goes up due to binge drinking and an increased tolerance to alcohol.

In a 2009 Psychology Today article, former self-described "high-functioning alcoholic," Sarah A. Benton writes that the biggest predictors of future alcoholism include genetics (which accounts for 50 percent of an individual’s risk of alcoholism); age at which a person started drinking (people who start drinking at age 15 have a 40 percent greater chance of becoming alcoholics regardless of family history); and preexisting problems with impulse control.

How can you tell if a friend is suffering from alcoholism?

Alcoholism is best understood as dependency; an alcoholic cannot be him or herself without alcohol. In Caroline Knapp’s 1996 book "Drinking: A Love Story," she describes carefully counting the bottles of wine at a vacation bungalow to make sure there would be enough. Knapp, unsatisfied, would pop out to her trunk for swigs from a handle of scotch. Another memoirist of rock-bottom, Mary Karr, describes her father going out to “check on the truck,” and his own handle of whisky. The point is that what was once a fun, social activity has become an addiction—and addiction is all about the individual turning inward.

Have you noticed that your friend has started showing up at the beginning of the evening as drunk as you might be at the end? Maybe you only see them have three or four glasses of wine at dinner, but they’re clearly wasted by dessert? When you find that your interactions with your friend always involve alcohol, it’s usually time to step back and take notice. Maybe the bad things that happen in a friend's daily life can be explained by certain behaviors: late for work, lost debit card, DUI. Alcoholics organize their lives around their drug of choice, and begin to neglect other responsibilities—jobs, children, social commitments, etc. Everything else is just collateral damage.

The slippery slope between “drinker” and “alcoholic” ends when alcohol becomes the star around which a person’s life revolves. Before-noon “eye-openers,” cocktails with lunch, a drink before, during, and after dinner, and a few night-caps before the whole thing starts over in the next morning’s hazy headache of forgetting and regret.

How to help.

The NIAAA offers a guide to treatment options if you or someone you love wants to seek help. It is essential to recognize the problem in order to deal with it honestly, but intervening successfully in a peer’s life requires the support of as many friends and family as possible. Recognizing the problem is a first step, but it’s not guarantee of recovery and addiction is something most afflicted people will struggle with the rest of their lives.