Relationship between Lifetime Smoking, Smoking Status at Older Age and Human Cognitive Function

Cigarette smoking is a major risk factor for clinical cardiovascular disease and may also be associated with poorer cognitive functioning in older age. We measured lifetime cigarette smoking, smoking status and cognitive function in over 2,000 men and women from the general population aged over 50 years with subclinical atherosclerosis (ankle brachial pressure index<or=0.95 but no history of clinical cardiovascular disease). In this population, an association was found between greater lifetime smoking and poorer cognitive function in men and between smoking cessation and better cognitive function in women. The former relationship appeared to reflect an association between smoking habit and prior cognitive function (in early life), whereas the latter remained significant after adjustment for tests of crystallised cognitive function, suggesting a relationship between continuing to smoke (as opposed to quitting) and age-related cognitive decline. Both relationships were independent of the degree of atherosclerosis (as measured using the ankle brachial pressure index), suggesting alternative underlying mechanisms for the association between smoking and human adult cognitive function.