‘Traffic-related’ risk is listed as a leading factor for dementia onset

Key points:

• In 2024, it is estimated that more than 421,000 Australians live with dementia

• The Australian Institute of Health and Welfare estimated almost 29,000 people are living with younger onset dementia, expected to rise to almost 41,000 people by 2054

• More than two-thirds of aged care residents have moderate to severe cognitive impairment

Researchers examined 161 risk factors for dementia and ranked their impact on a ‘weak spot’ in the brain, previously identified as a vulnerable network for the onset of schizophrenia and Alzheimer’s disease.

The study investigated genetic and modifiable influences on these fragile brain regions by looking at the brain scans of 40,000 participants aged over 45 and three modifiable factors stood out.

A modifiable risk factor, as opposed to genetic factors, is something that people can do to prevent their likelihood of developing dementia later in life, based on research.

The three biggest risk factors that stood out to the authors of the study, published in Nature Communications on March 27, were diabetes, alcohol intake and traffic-related air pollution.

These three risks can be further broken down into a list of 15 modifiable factors:

• blood pressure;
• cholesterol;
• diabetes;
• Weight;
• alcohol consumption;
• smoking;
• depressive mood;
• inflammation;
• pollution;
• hearing;
• sleep;
• socialisation;
• diet;
• physical activity and education.

University of Oxford Professor Gwenaëlle Douaud at the Nuffield Department of Clinical Neurosciences, who led the study, said researchers went into the study with the knowledge that there is a certain series of networks in the brain that degenerates as people age.

“[…] in this new study, we have shown that these specific parts of the brain are most vulnerable to diabetes, traffic-related air pollution — increasingly a major player in dementia — and alcohol, of all the common risk factors for dementia,” Professor Douaud said.

“We have found that several variations in the genome influence this brain network and they are implicated in cardiovascular deaths, schizophrenia, Alzheimer’s and Parkinson’s diseases, as well as with the two antigens of a little-known blood group, the elusive XG antigen system, which was an entirely new and unexpected finding.”

Professor Anderson Winkler, a co-author from the National Institutes of Health and The University of Texas Rio Grande Valley, added that the study was ‘special,’ based on the fact that they were able to look at how this brain network breaks down based on each factor.

“It is with this kind of comprehensive, holistic approach — and once we had taken into account the effects of age and sex — that three emerged as the most harmful: diabetes, air pollution and alcohol,” he said.

Previous research found metropolitan traffic may contribute to the development of dementia in other ways, such as closer proximity to road noise being associated with a 27 percent increased likelihood of developing Alzheimer’s disease.

For more information about driving and dementia, including the ‘dos and don’ts,’ please check out BetterHealth Victoria.

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