In contrast, among participants with alcohol problems, "never-smokers and former-smokers showed equivalent changes on all measures with increasing age as the never-smoking controls," he explained.
"These results indicate the combination of alcohol dependence and active chronic smoking was related to an abnormal decline in multiple cognitive functions with increasing age," Durazzo said, and that "the combined effects of these drugs are especially harmful and become even more apparent in older age."
He pointed out that other factors, including nutrition and exercise, may also influence brain function during early abstinence. He added that underlying medical issues including high blood pressure and diabetes as well as psychiatric conditions such as depression and post-traumatic stress disorder could also play a role.
Based on their findings, the authors suggested that as people get older, chronic smoking and heavy drinking are associated with increased oxidative damage to the brain.
"Oxidative damage results from increased levels of free radicals and other compounds that directly injure neurons and other cells that make up the brain. Cigarette smoking and excessive alcohol consumption expose the brain to a tremendous amount of free radicals," Durazzo explained.
While the study tied alcohol dependence combined with smoking to early brain aging, it didn't establish a cause-and-effect relationship.
The researchers advised that people seeking treatment for alcohol abuse should also be routinely offered help to quit smoking.
The U.S. National Institute on Alcohol Abuse and Alcoholism has more about effects of alcohol on the brain.
-- Mary Elizabeth Dallas
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