Smoking, drinking, and incident cognitive impairment: a cohort community based study included in the Gospel Oak project.

OBJECTIVES Recent longitudinal studies have reported that smoking increases risk for cognitive impairment and that moderate alcohol intake could be preventive. The association between both cigarette smoking and alcohol drinking and incident cognitive impairment was studied in a representative population. METHODS This is a 1 year prospective population based cohort study of all residents aged 65 or over in the electoral ward of Gospel Oak in London, UK (n=889). Cognitive impairment was assessed at baseline and 1 year later using the organic brain syndrome (OBS) cognitive impairment scale from the short CARE structured assessment. Subjects who were cognitively impaired at baseline were excluded from this analysis. RESULTS The prevalence of OBS cognitive impairment was 10.4% at index assessment and the 1 year cumulative incidence of cognitive impairment was 5.7%. Cognitive impairment was not associated with use of alcohol, although there was a non-significant association in the direction of a protective effect against onset of cognitive impairment for moderate drinkers compared with non-drinkers and heavy drinkers. Current smoking status predicted cognitive impairment (risk ratio (RR) 3.7; (95% confidence interval (95% CI)=1.1-12.3) independently from sex, age, alcohol, occupational class, education, handicap, depression, and baseline cognitive function. CONCLUSIONS Smoking seems to be a prospective risk factor for incident cognitive impairment; thus encouragement of older people to stop smoking could be considered as part of a strategy to reduce the incidence of cognitive impairment.