Elderly current smokers are at increased risk of dementia and cognitive decline compared with those who have never smoked and those who have given up, according to a new study by ANU researchers. They recommend that public health information about smoking include warnings about dementia risk.

Current older-aged smokers had an up to 80 per cent higher risk of Alzheimer’s disease and vascular dementia than their never smoked peers, according to study leader Associate Professor Kaarin Anstey, from the Centre for Mental Health Research. The results are published in the latest edition of the American Journal of Epidemiology.

The study looked at smoking as a risk factor for dementia by analysing the data 19 high quality longitudinal studies from around the world. It compared current smokers, ever smokers, former smokers and non-smokers, and their cognitive ability. The mean age of those studied was 74 years.

The analysis did not reveal an increased risk of dementia or cognitive decline for ever smoking compared with never smoking. However when former smokers were compared with never smokers, they were did show an increased risk of yearly decline in cognitive ability.

“Smoking cessation is associated with reduced risk of lung cancer, cardiovascular risk, and cancer. It’s therefore possible that the effects of smoking on cognition are not evident in a proportion of former smokers who may have ‘recovered’ from the detrimental effects of smoking on the brain and cognitive function.

“Ever smokers were at significantly lower risk than current smokers of Alzheimer’s disease and yearly cognitive decline, but were no different from current smokers regarding their risk of vascular dementia and any dementia,” Associate Professor Anstey said.

“Further research is required on the differences between ever-smoker and former smoker to determine the time period after which risk begins to decline. It’s possible that consistent differences between ever smokers and never smokers were not found because the category of ever smoker included such a broad range of possible smoking duration.

“But overall, the results of this study clearly show that, when compared with people who have never smoked, current smokers have an increased risk of dementia and cognitive decline ranging from 40 percent to 80 percent, depending on the type of dementia or cognitive outcome examined.

“Based on this research, public health information should be updated for smokers to include a warning that smoking may increase the risk of dementia,” Associate Professor Anstey said.

More information: Amanda Morgan, ANU Media Office, 02 6125 5575 / 0416 249 245