In a study of 287 men and women ages 31 to 60, researchers found that those with past alcohol-use disorders performed similarly on standard tests of cognitive function as those with no past drinking problems.
The findings were not as positive when it came to tobacco, however. In general, women who had ever been addicted to smoking had lower scores on certain cognitive tests than their non-smoking counterparts.
The same pattern was not true of men, researchers report in the March issue of the Journal of Studies on Alcohol and Drugs. The reasons for the disparate findings on alcohol and smoking are not fully clear.
Nor do they necessarily mean that serious alcohol problems would not affect long-term memory and other cognitive abilities. Most study participants who had ever had drinking problems met the criteria for alcohol abuse rather than the more serious diagnosis of dependence.
The findings are based on assessments of 115 men and 169 women with an average age of 43. Overall, women who reported having ever smoked 20 or more cigarettes a day scored lower than non-smokers on tests of executive function — that is, "higher-order" brain functions that include the ability to reason, plan and organize.
As for why smoking was related to cognitive scores only among women, it’s possible that there is a role for estrogen, says Kristin Caspers, a researcher at the University of Iowa.
Animal research suggests that nicotine lowers blood estrogen levels and may inhibit the positive effects of the hormone on brain cells. Sixty percent of the women in the current study were
between the ages of 40 and 54, when menopause usually occurs.
In theory, nicotine may exacerbate any brain-cell effects of fluctuating estrogen levels in women as they age, the researchers speculate.