Smoking linked to higher risk of dementia, Curtin-led research finds

A major review of more than two million people has found current smokers face a higher risk of dementia, with researchers calling for brain health to feature more prominently in anti-smoking campaigns.

Led by Curtin University researchers, the study examined the link between smoking and three forms of dementia, including all cause dementia, Alzheimer’s disease and vascular dementia, providing the most comprehensive update to the evidence in more than a decade.

The systematic review and meta-analysis examined 61 studies involving about 2.8 million people.

Researchers found people who currently smoke had a 31 per cent higher risk of developing dementia, a 40 per cent higher risk of Alzheimer’s disease and a 52 per cent higher risk of vascular dementia than people who had never smoked.

The study also found the risk of dementia increased with the number of cigarettes smoked.

People smoking 10 cigarettes a day had a 16 per cent higher risk of dementia, while those smoking 20 a day had a 34 per cent higher risk, compared with people who had never smoked.

Lead researcher Professor Mario Siervo, from the Dementia Centre of Excellence at Curtin’s enAble Institute and School of Population Health, said the findings highlighted the importance of looking beyond the well-known links between smoking, cancer and heart disease.

“We know smoking can cause serious harm to our health, but its impact on brain health also deserves attention,” Professor Siervo said.

“Our findings show current smoking is linked to a higher risk of dementia, and that risk increases as people smoke more.”

Senior author of the paper Professor Blossom Stephan, also from the Dementia Centre of Excellence at Curtin’s enAble Institute, said the findings highlight the importance of considering the wider health impacts of smoking.

“Brain health should be part of the conversation when we talk about the dangers of smoking and the benefits of quitting.”

The study also found former smokers had a lower risk of dementia than people who continued to smoke. Overall, former smokers did not have a higher risk of dementia than people who had never smoked.

While the research cannot prove smoking directly causes dementia, the findings add to growing evidence that quitting smoking may be an important part of reducing dementia risk.

Co-author and Dementia Australia Chief Executive Officer Professor Tanya Buchanan said the findings reinforced the importance of helping people understand the modifiable risk factors linked to dementia risk.

“Dementia has a life-changing impact on people, their families and their communities,” Professor Buchanan said.

“Research like this helps build our understanding of the modifiable risk factors linked to dementia and highlights the importance of looking after our brain health.

“It is equally as important to understand that dementia risk reduction is a shared responsibility, which is why we need policies and actions from all levels of government, alongside providing information and research, to make it easier for all Australians to look after their brain health.”

The researchers also highlighted a gap in Australia’s approach to tobacco control.

While smoking has been identified as a risk factor for dementia in three major international reports, dementia and brain health are not directly addressed in Australia’s National Tobacco Strategy 2023–2030.

Cancer Prevention and Research Director at Cancer Council WA, Melissa Ledger, said the findings provided another reason to maintain and refresh public health education campaigns and messages about the dangers of smoking.

“We’re really proud to have delivered what we believe was the first Australian smoking and brain health campaign earlier this year, to start raising awareness of the link between smoking and dementia, but there is more to say about the harm smoking can cause,” Ms Ledger said.

“This research provides an opportunity to talk about the health benefits of quitting smoking in a new way.

“Making sure people understand the full impact of smoking, and the benefits of quitting, is an important part of preventing smoking-related disease.”

The researchers said including brain health in anti-smoking campaigns, cigarette packet warnings and quit-smoking programs could help more people understand the long-term risks of smoking and the benefits of quitting.

They said further research was needed to understand how the age at which a person quits, and how long they have been smoke-free, affect dementia risk.

The paper, ‘Smoking and Dementia Risk: An Updated Systematic Review and Meta-Analysis of 61 Prospective Cohort Studies and Implications for Tobacco Control,’ has been published in eClinicalMedicine.