Quitting smoking is also good for your brain

Title Impact of smoking history on cognitive decline: the Whitehall II cohort study
Authors Sabia S, Elbaz A, Dugravot A, Head J, Shipley M, Hagger-Johnson G, Kivimaki M, Singh-Manoux A
Ref Arch Gen Psychiatry. 2012 Feb 6 [EPub ahead of print]
Lay summary

Smoking is increasingly recognized as a risk factor for dementia in the elderly and the number of dementia cases worldwide, estimated at 36 million in 2010, is on the rise and is projected to double every 20 years. This study examined the association between smoking history and cognitive decline in the transition from midlife to old age. The study used data from 5,099 men and 2,137 women in the Whitehall II study, with a mean age of 56 years at the first cognitive assessment. Data on smoking status were assessed 6 times over 25 years and cognitive function three times over 10 years.

Smoking in men was found to be associated with more rapid cognitive decline equivalent to 10 years of ageing. In addition, men who quit smoking in the 10 years preceding the first cognitive measure were still at risk of greater cognitive decline, especially in executive function (an umbrella term for various complex cognitive processes involved in achieving a particular goal). However, long-term ex-smokers did not show faster cognitive decline. Finally, the results show that the association between smoking and cognition, particularly at older ages, is likely to be underestimated owing to higher risk of death and dropout among smokers. No association between smoking and cognitive decline in women was found, although the underlying reasons remain unclear. One possible explanation for the sex difference might be the greater quantity of tobacco smoked by men.

In conclusion, this study shows evidence of the benefits of quitting smoking for the brain.

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