June 9, 2008 -- Smoking in midlife results in poor memory and makes it harder to think and learn, according to research published in the June 9 issue of Archives of Internal Medicine.
What's more, developing cognitive problems in your 30s, 40s, and 50s may speed the onset of dementia. Smoking damages blood vessels, including those in the brain. Scientists recently concluded that smoking is a risk factor for dementia.
However, the link between smoking and cognitive problems has been hard to determine because few study patients return for follow-up visits or they die of smoking-related diseases before the research is completed.
For the current study, Severine Sabia, MSc, of the Institut National de la Sante et de la Recherche Medicale in Villejuif, France, and colleagues analyzed data from London-based civil servants aged 35 to 55 first enrolled in the Whitehall II study between 1985 and 1988. The study participants answered questions about their smoking habits and completed memory, reasoning, vocabulary, and verbal fluency tests on two separate occasions in 1997-1999 and then five years later.
The first round of cognitive testing showed that smokers were more likely to have the lowest scores than those who never lit up. "Smoking in middle age is associated with memory deficit and decline in reasoning abilities," the study authors say in a news release.
Ex-smokers tested better than current smokers on vocabulary and verbal fluency tests and were less likely to have cognitive deficits in memory.
Those who kicked the habit before the study started or during the 17 years of follow-up also reported drinking less alcohol and eating more fruits and vegetables.
However, those who smoked when the study started were less likely to take the cognitive tests and more likely to die after the 17 years of follow-up.
"Our results ... suggest that the association between smoking and cognition, even in late midlife, could be underestimated because of higher risk of death and non-participation in cognitive tests among smokers," the authors say.