Memory Goes Up in Smoke, Dementia at Risk for Middle-Aged Smokers

In a large meta-analysis of more than 10,000 British civil servants, researchers have determined that those who had a long-term smoking habit were more likely to suffer from memory impairments upon reaching middle age than their non-smoking counterparts. Memory defects that become apparent in middle age are thought to hasten the onset of age-related dementia.

Using data gleaned from the Whitehall II study of 10,308 civil servants based in the London area, the research team from the Institut National de la Sante et de la Recherche Medicale, in Villejuif, France, used follow-up data that covered an average of 17.1 years per study participant to document the effects of smoking on cognitive function during middle age.

All study participants were between the ages of 35 and 55 during the study’s enrollment period, spanning 1985 to 1988. Follow-up assessments, including smoking habit, were conducted between 1997 and 1999 and again five years later.

During the first follow-up assessment, in the 1990s, only 5,388 participants returned to undergo a battery of tests designed to measure memory as well as reasoning, verbal fluency, and vocabulary. Five years later, only 4,659 returned for assessment.

Study participants who smoked at the outset of the Whitehall II study were less likely to return for cognitive testing and were more likely to have died during the follow-up phase of the study. Of the smokers returning for assessment, they were the group who performed the lowest on cognitive function during the first round of follow-up assessments. Smokers who quit the habit after enrolling for the study scored higher in several areas, including a gain over the smokers of about 30% in vocabulary and verbal skills. Ex-smokers also exhibited healthier lifestyle choices, too, including limited consumption of alcohol, more physical activity, and a diet richer in fruits and vegetables.

The research team, led by Severine Sabia, MSc, identifies four key findings of the study:

Middle-aged smokers are more likely to exhibit a decline in the ability to reason effectively and a greater incidence of memory deficiencies than non-smokers.
The sooner one quits smoking, the less likely he or she is to experience smoking-induced defects of cognition involving vocabulary, verbal abilities, and memory.
Even in smokers who wait till middle age to quit, health benefits will become apparent.
The influence of smoking on cognitive function during midlife is probably underestimated due to the increased risk of death in the long-term smokers during the trial and its follow-up period and because this segment of the study population proved less likely to return for evaluation.

The research team, citing success of public service campaigns of the past 20 years that speak out against smoking, urges public health officials to continue anti-smoking campaigns designed to reach smokers of all ages.

Source: JAMA

Filed under: Lifestyle, Medical Research, Memory, Smoking