Alcoholics who smoke appear to lose more brain mass than alcoholics whodon't smoke, according to a study at the San Francisco VA MedicalCenter.
It is already well-known that the brains of long-term alcoholicsatrophy and shrink, the study authors say, but the new findings are thefirst evidence that cigarette smoking might contribute to that atrophy,particularly in grey matter of the parietal and temporal lobes.
Fifty to 90 percent of alcoholics also are smokers, according to DieterMeyerhoff, PhD, a radiology researcher at SFVAMC and the principalinvestigator of the study
"Just looking at the amount of tissue mass lost due to either drinkingor smoking, alcoholics who smoke show a greater loss in some regions ofthe brain compared to alcoholics who don't smoke," says Meyerhoff, whoalso is a professor of radiology at the University of California, SanFrancisco.
The study, which was published in the August 2005 issue of Alcoholism:Clinical and Experimental Research, compared 37 recovering alcoholicsbetween the ages of 26 and 66 with a control group of 30 healthy lightdrinkers. The researchers used magnetic resonance imaging, a safe,non-invasive imaging technique, to measure brain volumes of the studyparticipants.
They discovered that the more severe the tobacco habit, the greater thebrain injury. "In smoking alcohol-dependent individuals, smallerregional [brain] volumes are related to greater cigarette-smokingseverity," according to the study findings, with severity measured bylevel of nicotine dependence, cigarettes smoked per day, and years ofsmoking.
The alcoholics (24 smokers and 13 non-smokers) averaged around 400drinks per month for three years prior to the study; the light drinkers(seven smokers and 23 non-smokers) averaged between four and 11 drinksper month before the study and had no history of alcohol abuse ordependence. The alcoholics were sober for approximately one week beforethe study began.
The study uncovered no apparent differences in brain volume between smoking and non-smoking light drinkers.
Another key finding was that among non-smoking alcoholics, there was adirect relationship between brain volume and cognitive function: thehigher the volume, the better the function. However, no suchrelationship was apparent among smoking alcoholics, according toco-author Timothy Durazzo, PhD, an associate radiology researcher atSFVAMC. Nor has such a relationship been measured before in previousstudies on alcohol abuse and brain volume, he says.
"And this makes us wonder if what has been reported in the literatureof alcoholism could have been obscured or distorted by combiningsmokers and non-smokers in the same studies," Durazzo adds.
In their paper, the researchers speculate that smoking "disrupts these[brain] structure-function relationships," possibly through itsdetrimental effects on brain volume or on brain neurochemistry.
Meyerhoff and his co-authors emphasize that their results areretrospective -- that is, they discovered the apparent effects ofsmoking during statistical analysis of the participants in an earlierstudy they conducted on alcoholism and its effects on the brain. Theythen went back, re-classified each study participant as smoking ornon-smoking, and analyzed brain volumes accordingly.
The authors say that if replicated in other studies, their results willraise several potentially important questions. The first is whetherrecovering alcoholics should also be treated for smoking -- and if so,at what point during their treatment. At present, alcohol treatmentprograms such as Alcoholics Anonymous do not discourage smoking or evenaddress the issue, they say.
Beyond that, says Durazzo, there is the potential effect of smoking oncognitive dysfunction, which is common among older long-termalcoholics. "Right now, our study participants are relatively young,around 50," he notes. "But will the combination of smoking anddrinking, or continued smoking during abstinence from alcohol, put themat greater risk for cognitive dysfunction as they age?" Finally, saysMeyerhoff, there is the question of whether smoking has an effect onphysical recovery from alcohol abuse. "In alcoholics who stop drinking,we know that there is recovery from at least some of these injuries tothe brain -- but is this recovery affected by continued smoking?"Meyerhoff and his team are conducting a study to explore that questionright now.
In the future, the researchers plan a prospective study that will useMRI to compare brain volumes between smoking and non-smoking lightdrinkers and smoking and non-smoking alcoholics, with the hope ofreplicating the results of their current retrospective study.
Other authors of the study include Stefan Gazdzinki, PhD, of UCSF andthe Northern California Institute for Research and Education (NCIRE);Colin Studholme, PhD, of UCSF; Enmin Song, PhD, of NCIRE; and PeterBanys, MD, of SFVAMC and UCSF.
The research was supported by a grant from the U.S. Public Health Service that was administered by NCIRE.
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