Professor Kaarin Anstey
We conducted what we call a “meta-analysis” of the smoking literature. We collated all of the published studies that observed smoking, and then followed people to see whether or not they developed cognitive decline, Alzheimer's disease, vascular dementia or all-cause dementia. And we found that smoking in older adults increased their risk of dementia by 70%. And it was pretty much the same for all types of dementia.
Now, unfortunately, we didn’t have the data from middle age to be able to see if that was true of midlife smokers and what happens if people give up. There is one very interesting study that was conducted in Western Australia, on a group of people who entered a smoking cessation program. They took brain scans of these people at the beginning of the program and at the end, and they also tested their cognition. What they found was that the people who gave up smoking had less brain atrophy than the people who continued to smoke. And they also found that people who gave up smoking had less cognitive decline. So that study is really important in showing there are actually benefits for the brain, even giving up smoking in older age.
Smoking impacts on the brain through multiple pathways. We know that smoking increases the rate of ageing on all of the biomarkers that we can measure. Smoking increases the risk of vascular events, so small strokes and stroke. It increases the rate of brain atrophy. It’s a neurotoxin, and of course it increases the risk of a lot of other diseases such as cancer, which can also ultimately impact on the brain. So it’s a pretty general negative risk factor, a negative behaviour to undertake for brain ageing.