Sensitivity to alcohol connected with alcoholism risk

Being able to drink your buddies under the table may garner grudging respect around the bar, but it bodes poorly for the long term. A new study finds that young men for whom alcohol has little effect face a greater risk of developing alcoholism later in life than those who readily feel alcohol’s effects.

Reporting online May 22 and in the September issue of Alcoholism: Clinical & Experimental Research, scientists find that the added risk a man carries by being more resistant to alcohol’s effects endures even after accounting for other factors such as teenage drinking habits and family history of alcohol abuse.

Since the 1970s, scientists have been investigating an apparent link between a person’s resistance to alcohol’s effects and a higher risk of alcohol abuse later. “But many didn’t believe it was real,” says Marc Schuckit, a psychiatrist at the University of California, San Diego in La Jolla and the Veterans Affairs San Diego Healthcare System.

To nail down the correlation, Schuckit and his colleagues analyzed data collected on 297 men, all about 20 years old, between 1978 and 1988. Every participant underwent tests to measure his response to alcohol. Despite similar blood-alcohol levels, the degree of impairment varied substantially among the men. The young men also provided drinking-related information, including how much they drank, their age when they had their first drink and whether alcoholism ran in their families.

The researchers interviewed the volunteers again after 10, 15, 20 and 25 years.  These follow-up visits showed that men who were least affected by alcohol at age 20 were two to three times as likely to be alcoholic at age 30 or 40 as were those who were easily affected by alcohol as young men, Schuckit says. These differences in risk remained even when the researchers compared only men for whom the other risk factors — family history, age of drinking onset and amount they drank when young — were equal.

The adjustments for earliest drinking age and quantity of consumption help to ensure that the measured effect “was not just a consequence of earlier, heavier drinking or tolerance,” the authors note.

Schuckit speculates that 60 percent of alcoholism risk is genetic and about 40 percent stems from lifestyle and other environmental factors. Resistance to alcohol’s effects — a different measure from tolerance, which to some extent can come from a familiarity with alcohol’s effects — would seem to be a hardwired genetic trait, he says. Schuckit and his team are currently investigating genes that they suspect play a role in alcoholism risk.

While sensitivity to alcohol’s effects might offer some protection against future alcohol abuse, other factors — including those that the researchers accounted for in this study — could still increase the risk. And less common traits, such as having bipolar disorder or being highly impulsive, might add to the danger, Schuckit notes. Thus, just being very sensitive to alcohol’s effects is no guarantee that a person won’t abuse it, he says.