Smoking Worsens Alcohol-Induced Brain Damage
Researchers used MRI to tease out cigarettes' effect
WEDNESDAY, Dec. 15, 2004 (HealthDayNews) -- People who drink to excess also tend to be chronic smokers, and a new report suggests the combination of the two might prove more toxic than either one alone.
Previous research into the effects of alcohol dependence largely glosses over the question. But a small study in the December issue of Alcoholism: Clinical and Experimental Research suggests there's reason for concern.
"Chronic cigarette smoking increases the severity of brain damage associated with alcohol dependence," said study author Timothy C. Durazzo, a neuropsychologist and neuroscience researcher at the San Francisco Veterans Administration (VA) Medical Center.
The regions of the brain with the greatest combined damage were the frontal lobes -- the mind's short-term storage sites. As for why that is, Durazzo could not speculate. But given the importance of that region of the brain for everyday functioning, any exacerbation of tissue damage could further compromise recovering alcoholics' ability to manage daily activities or weigh the consequences of their actions, he said.
It's estimated that 80 percent of alcohol-dependent individuals smoke regularly, the study authors report. And although chronic, heavy alcohol consumption is known to cause brain damage, past research failed to tease out the independent effects of smoking -- or its potentially compounding effects on the brains of alcoholics.
"Smoking has been treated as a nuisance variable or it has been completely ignored," Durazzo said.
For the study, he and his colleagues compared 24 recovering alcoholics who had abstained from drinking for a week with 26 "light-drinking" control subjects. Each of those groups included a mix of smokers and nonsmokers -- 14 smokers and 10 nonsmokers among the recovering alcoholics and seven smokers and nine nonsmokers in the control group.
Using magnetic resonance (MR) spectroscopy, a powerful type of imaging that captures signs of tissue damage across all areas of the brain, the research team compared and contrasted the groups. They also conducted a brief neurocognitive survey.
The results show that chronic cigarette smoking increases the severity of brain damage associated with alcohol dependence. Compared with other groups, for example, recovering alcoholics who are smokers had the lowest levels of N-acetylaspartate (NAA), an amino acid whose concentration is believed to be an indicator of nerve cell viability, the researchers said.
Cigarette smoking, independent of alcohol consumption, also had adverse effects on tissue involved in motor function and balance -- an unexpected but important finding, Durrazo noted. While the effects of smoking on the heart, lungs and cardiovascular system are well-documented, very little is known about its damage to the brain, he explained.
Overall, the findings suggest that researchers need to account for the independent and interactive effects of cigarette smoking and alcohol dependence on brain functioning and tissue damage. The authors also believe the study has important public health implications.
"If enough information can be given to kids or people that are currently smoking about this -- and it just increased their knowledge of the risk -- it might impact things to get more people to not smoke or encourage them to stop," Durrazo said.
In a separate study published in the same journal, researchers at Princeton University in New Jersey and Rockefeller University in New York City used rats to show that alcoholism and excessive food intake may share the same chemical pathways in the brain.
"Perhaps there should be a renewed focus in alcohol research on understanding the interrelationship and overlap between the mechanisms that control food intake and nutrition with those involved with excessive alcohol intake and dependence," Michael J. Lewis, a senior fellow in the Department of Psychology at Princeton, said in a statement.
For more on alcohol's effects on the brain, visit the National Institute on Alcohol Abuse and Alcoholism.