Smoking and cognitive change from age 11 to 66 years: a confirmatory investigation.

Previously we reported that smoking is associated with a small relative decline in cognition from childhood to old age. In this study we perform confirmatory analyses on a further wave of data collected from 298 of the participants, all with age 11 IQ scores, at age 66years, 2years after the original observations. Non-smokers scored a mean 4.9 memory test and 2.6 information processing speed test points and ex-smokers 3.5 memory test and 1.9 information processing speed test points higher than current smokers respectively over the two waves of testing, equivalent to 4-8% of mean test scores, adjusted for the effects of childhood IQ. Across tests a 100l/min higher Peak Expiratory Flow Rate was associated with a 3-4% higher test score at ages 64 and 66years. These data confirm the adverse effect of smoking on information processing speed, and provide new evidence for a similar adverse effect on memory for people in their mid-sixties.