French researchers have identified a link between smoking and poor memories among middle-aged adults. The results of their study appear in the June 9 issue of Archives of Internal Medicine.
Séverine Sabia, M.Sc. (Institut National de la Santé et de la Recherche Médicale, Villejuif, France) and colleagues have built upon a previous meta-analysis that has demonstrated smoking as a risk factor for developing dementia. It is a particular challenge, however, to establish an association in older adults between smoking and cognitive function (such as thinking, learning, and memory). The difficulty lies in the failure of participants to return for follow-up visits and as well as their high likelihood of dieing from smoking-related diseases.
These recent findings come from an analysis of 10,308 civil servants based in London. The participants were aged 35 to 55 and enrolled in Whitehall II study between 1985 and 1988. At the beginning of the study and again between 1997 and 1999, researchers assessed the participants’ smoking habits. Between 1997 and 1999, researchers administered tests of memory, reasoning, and vocabulary and verbal fluency to 5,388 participants. Five years later, 4,659 were re-tested.
Sabia and colleagues found that smokers at the beginning of the study we more likely to die and less likely to receive cognitive testing during the 17.1 years (average) of follow-up. The first round of cognitive testing indicated that compared to those who had never smoked, smokers were in the lowest-performing quintile (20%) of test scores. For those who smoked but quit before the beginning of the study, their likelihood of having poor vocabulary and low verbal frequency test scores was 30% less than smokers. The researchers also found that other health habits were improved for participants who quit smoking during the study: they drank less alcohol, became more physically active, and ate more fruits and vegetables.
The authors lay focus on four key findings: “First, smoking in middle age is associated with memory deficit and decline in reasoning abilities. Second, long-term ex-smokers are less likely to have cognitive deficits in memory, vocabulary and verbal fluency. Third, giving up smoking in midlife is accompanied by improvement in other health behaviors. Fourth, our results based on a large prospective cohort study of middle-aged British civil servants suggests 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.”
It is possible, suggest the authors, that individuals with midlife cognitive impairment may develop dementia more quickly. “During the past 20 years, public health messages about smoking have led to changes in smoking behavior,” they conclude. “Public health messages on smoking should continue to target smokers of all ages.”
Smoking History and Cognitive Function in Middle Age From the Whitehall II Study
Séverine Sabia; Michael Marmot; Carole Dufouil; Archana Singh-Manoux
Archives of Internal Medicine (2008). 168[11]:1165 – 1173.
Written by: Peter M Crosta