Alcohol-use disorders (AUDs) can damage the brain, particularly the frontal and parietal cortices, although this damage is at least partially reversible with sustained abstinence from alcohol. Chronic smoking is extremely common among individuals with AUDs.
A new study has used longitudinal magnetic resonance imaging (MRI) of brain blood flow to show that smoking makes it harder for brain blood flow to recover from long-term heavy drinking.
Results will be published in the August issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.
"The brain's frontal lobes are involved in higher-order cognitive function, such as learning, short-term memory, reasoning, planning, problem solving, and emotional control," explained Anderson Mon, senior research fellow in the department of radiology at the University of California, San Francisco and corresponding author for the study. "The parietal lobes are involved in aspects of attentional regulation and visuospatial processing. Chronic and excessive drinking is associated with neurobiological abnormalities in these regions, which contribute to the cognitive dysfunction frequently observed in those with AUDs after detoxification."
Cerebral perfusion is a measure of the amount of blood flow to brain tissue per unit time. A normal, uninterrupted flow of blood through the brain is necessary to supply brain tissue with sufficient essential compounds and oxygen for normal metabolism, and will also carry away metabolic byproducts. The brain is only about 1/50th of total body weight, but it demands about 20 percent of the heart's oxygen-rich blood.
"In general, AUDs are associated with reduced perfusion," said Mon. "With abstinence from alcohol, brain perfusion abnormalities may recover, but there are several factors that may influence recovery, such as age, diet, exercise, genetic predispositions and - the topic of our research -other substances such as tobacco products."
Mon and his colleagues measured brain perfusion in the frontal and parietal cortices of three groups of study participants: 19 non-smoking alcohol-dependent (ALC) patients, and 22 smoking ALC patients at one and five weeks of abstinence from alcohol; as well as 28 age-matched non-smoking, light-drinking controls.
Results showed that even though cerebral perfusion among the ALC individuals, as a whole, improved with abstinence from alcohol, those ALC who were chronic smokers demonstrated significantly less perfusion recovery, particularly in the frontal lobes.
"At one week of abstinence, both smoking and non-smoking ALC patients had similar frontal and parietal gray matter perfusion; and both groups had lower perfusion than normal controls," said Mon. "However, after five weeks of abstinence, frontal and parietal gray matter perfusion of the non-smoking ALC patients recovered to normal control levels, whereas the smoking ALC group essentially showed no recovery."