A new study says that casual smokers are 16 times more likely than non-smokers to indulge in hazardous drinking.
The study also suggests that casual smokers are at a five-fold risk of developing alcohol-use disorders (AUDs).
"Our goal in this study was to look at a range of smoking behaviours - daily smoking, non-daily smoking, non-smoking - and associations with binge drinking, hazardous drinking, and AUDs," said Sherry A. McKee, associate professor of psychiatry at Yale University School of Medicine.
"This can advance our understanding of the range of drinking patterns, and also the developmental trajectory of problem drinking," Shiffman added.
Using the National Epidemiological Survey on Alcohol and Related Conditions data, the researchers queried 5,838 young adults on their current smoking behaviours (during the preceding 12 months) as well as weekly consumption of alcohol, frequency of alcohol use, frequency of binge-drinking behaviour, rates of hazardous drinking.
They found that non-daily or casual smokers were 16 times more likely to be hazardous drinkers, and five times more likely to meet criteria for an AUD.
"We anticipated that the associations between alcohol use and smoking would be greatest in non-daily smokers, but were surprised by the degree of the associations," said McKee.
"While casual smoking was more common in college students, the relationships between smoking and drinking behaviour were the same for young adults whether they were students or not."
"Even though non-daily smokers were less likely than daily smokers to drink daily, they were more likely to exceed weekly and daily quantities defined as hazardous," said Shiffman.
"So, even though daily smokers drank more, non-daily smokers drank more hazardously," Shiffman added.
The results will be published in the December issue of Alcoholism: Clinical and Experimental Research.