Someone who has a low level of response (LR) to alcohol, meaning relatively little reaction to alcohol, has a higher risk for developing alcohol-use disorders (AUDs). A study that examined the influence of LR in conjunction with other characteristics – like family history of AUDs and age of drinking onset – has found that LR is a unique risk factor for AUDs across adulthood and is not simply a reflection of a broader range of risk factors.
"If a person needs more alcohol to get a certain effect, that person tends to drink more each time they imbibe," explained Marc A. Schuckit, director of the Alcohol Research Center, Veterans Affairs San Diego Healthcare System, professor of psychiatry at the University of California, San Diego, and corresponding author for the study.
"Other studies we have published have shown that these individuals also choose heavy drinking peers, which helps them believe that what they drink and what they expect to happen in a drinking evening are 'normal,'" he said. "This low LR, which is perhaps a low sensitivity to alcohol, is genetically influenced."
Schuckit and his colleagues examined 297 men participating in the San Diego Prospective Study, originally recruited and tested on their level of reaction to alcohol when they were 18 to 25 years old. Each reported on family history of AUDs, typical drinking quantity, age of drinking onset, body mass index, and initial age at recruitment for the study. AUDs were evaluated at 10-, 15-, 20-, and 25-year follow-ups.
Results showed that a low LR to alcohol predicted AUD occurrence over the course of adulthood even after controlling for the effects of other robust risk factors. In short, LR is a unique risk factor for AUDs across adulthood, and not simply a reflection of a broader range of risk factors.
"A low LR at age 20 was not just a reflection of being a heavier drinker at age 20 when we tested these men, and it wasn't an artifact of an earlier onset of drinking," said Schuckit. "We showed that a low LR at 20 predicts later heavy drinking and alcoholism even if you control for all these other predictors of alcohol problems at age 20."
Schuckit added that the study's method of examination – establishing multiple predictors at age 20, revisiting participants about every five years, and securing a response rate of about 94 percent – strongly show that LR is consistent and powerful in predicting alcoholism."
"Because alcoholism is genetically influenced, and because a low LR is one of the factors that adds to the risk of developing alcoholism," said Schuckit, "if you're an alcoholic, you need to tell your kids they are at a four-fold increased risk for alcoholism. If your kid does drink, find out if they can 'drink others under the table,' and warn them that that is a major indication they have the risk themselves. Keep in mind, however, that the absence of a low LR doesn't guarantee they won't develop alcoholism, as there are other risk factors as well."
It's not all bad news, Schuckit added. "We are looking for ways to identify this risk early in life, and to find ways to decrease the risk even if you carry a low LR … so there is hope for the future."
- The Relationships of the Level of Response to Alcohol and Additional Characteristics to Alcohol Use Disorders across Adulthood: A Discrete-Time Survival Analysis. Alcoholism: Clinical & Experimental Research, In Print September 2009
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