Smoking Interferes With Thinking And Memory In Recovering Alcoholics

Not only did the smokers improve less, but their overall scores were lower than the non-smokers on most neurocognitive measures tested by the researchers.

"This suggests that continued smoking during abstinence from alcohol may adversely affect recovery," says Timothy Durazzo, PhD, the study's lead author and a research scientist in radiology at SFVAMC.

The study appears in the July, 2007 issue of Alcoholism: Clinical & Experimental Research.

Durazzo, who is also an assistant adjunct professor of radiology at the University of California, San Francisco (UCSF), says the study is significant in light of previous research indicating that 60 to 80 percent of people who seek treatment for alcoholism are chronic smokers.

"It's well-established that chronic alcohol abuse leads to abnormalities in brain neurobiology and neurocognitive function, and it's also been shown that smoking itself leads to neurobiological and neurocognitive dysfunction," he says. "We wanted to learn what effect continued chronic smoking might have on changes in neurocognitive function during abstinence from alcohol. This issue had not been investigated before."

The researchers compared neurocognitive function among 13 non-smoking recovering alcoholics and 12 actively smoking recovering alcoholics recruited from two substance abuse recovery programs in San Francisco. After approximately one month of self-reported abstinence from alcohol, the subjects were tested on an array of neurocognitive abilities known to be affected by chronic alcohol abuse: auditory/verbal learning and memory; visual/spatial learning and memory; cognitive efficiency (speed and accuracy of intellectual task performance); executive skills (higher order thinking, reasoning, judgment, and planning); processing speed; working memory (short-term memory); motor functioning; and postural stability. The results were compared with those of 22 non-smoking, light drinking controls.

After six to nine months of alcohol abstinence, the subjects and controls were re-tested. The smokers showed significantly less improvement than the non-smokers in cognitive efficiency, executive skills, working memory, and visual/spatial learning and memory. Overall, their performance in tests of auditory/verbal learning and memory, cognitive efficiency, executive skills, processing speed, and working memory was inferior to that of the non-smokers.

Additionally, the smokers demonstrated lower recovery in markers of neuronal integrity and cell membrane health than the non-smokers.

"This indicates that the smokers showed less recovery over time and were functionally inferior to the non-smokers at six to nine months of abstinence," observes Durazzo. The controls showed no significant change over time.

"Overall, our studies with alcoholics, both those who receive treatment and those who do not, provide converging lines of evidence suggesting that chronic cigarette smoking adversely affects recovery of both neurobiology and neurocognition in people who drink," says principal investigator Dieter Meyerhoff, Dr.rer.nat., SFVAMC radiology researcher and professor of radiology at UCSF. "These studies contribute to the growing body of data linking chronic smoking to brain injury and cognitive dysfunction."

Durazzo says that the exact mechanisms by which smoking affects cognition and brain neurobiology have yet to be determined. He observes that the distinction must be made between nicotine by itself, which is found in cigarettes and has been shown in some studies to enhance cognition over the short term, and cigarette smoke, "which contains at least four thousand different compounds, including a number of carcinogens and other toxins. We feel that it is most likely the cumulative effect of chronic exposure to the noxious compounds in the smoke that might be affecting smokers' recovery."

Durazzo cautions that because of the small number of subjects, the study results are preliminary and should not be generalized to all recovering alcoholics.

Nonetheless, he says that the long-term benefit of quitting alcohol and tobacco simultaneously is becoming more and more apparent to researchers and clinicians. "In terms of addiction, it's been shown that alcohol and nicotine reinforce each other's rewarding properties. Alcoholics tend to smoke, and smoking may serve as a potential cue or trigger for the urge to drink. So if you eliminate a trigger for alcohol craving, you may have a better chance of staying sober."

Durazzo also points out that the mortality rate associated with chronic cigarette smoking is four times greater than mortality related to alcoholism. "Simply for that reason, it may be advisable to encourage individuals seeking treatment for alcoholism to consider participating in a smoking cessation program at the same time."

Durazzo says the next step for the researchers is a comparison of physical changes in the brain ---- volume, metabolites (the chemical products of brain metabolism), and blood flow ---- in the same group of subjects during extended abstinence from alcohol. "Those data are being analyzed now," he reports, "and we hope to learn to what degree these changes relate to the differences we have observed in neurocognitive recovery in smoking and non-smoking alcoholics."

Coauthors of the study are Johannes C. Rothlind, PhD, of SFVAMC and UCSF; Stefan Gazdzinski, PhD, of UCSF and the Northern California Institute for Research and Education (NCIRE); and Peter Banys, MD, of SFVAMC and UCSF.

The research was supported by a grant from the National Institutes of Health that was administered by NCIRE.