An unhealthy Western diet accelerates cognitive decline among older adults carrying a specific genetic risk factor for Alzheimer’s disease, according to new Australian-led research tracking 185 participants over seven years. The study, titled Dietary Patterns and Cognitive Decline in Older Adults: Findings from the Western Australia Memory Study and published in the journal Nutrients, reveals that gene-diet interactions significantly impact brain health during aging.
As the world grapples with the growing public health challenge of dementia, there has been increasing academic interest in identifying lifestyle factors which may help maintain people’s brain health as they age. Scientists tracking older adults in Perth for more than seven years have found that an unhealthy Western-style diet is linked to faster cognitive deterioration, but only for individuals carrying a specific genetic predisposition to Alzheimer’s disease. The research, drawn from data in the Western Australia Memory Study, highlights the complex interplay between daily food choices and inherited biological risks.
Tracking Diet and Cognition in Perth Over Seven Years
Researchers followed 185 older adults living in Perth, the capital of Western Australia, examining whether regular eating habits influenced changes across various domains of thinking. Throughout the study, participants completed a series of cognitive tests to assess their attention, memory, executive function, language, recognition memory, and general cognitive ability. None of the participants had diagnosed dementia when they entered the study, which was led by Murdoch University and Alzheimer’s Research Australia.
To analyze dietary habits, investigators grouped the participant’s diets into two main groups. The unhealthy Western diet consisted of food such as red and processed meat, chips, pizza, sweets, refined grains, and beer. Conversely, the healthier Prudent diet consisted of things like fruit, vegetables, leafy greens, garlic, and whole grains.
Participants also underwent testing for genetic susceptibility factors, specifically identifying the apolipoprotein E (APOE) variant, which is the strongest common genetic risk factor for Alzheimer’s disease.
How the APOE ε4 Allele Changes Dietary Impact
The investigation uncovered that the negative impact of food patterns was not universal across all participants. Instead, vulnerability depended heavily on genetic profile.
Diet is particularly interesting because it is often easily modifiable, but people may not respond to dietary patterns in the same way,
said lead author Dr Carolina Blagojevic Castro, from Murdoch University’s Centre for Healthy Ageing.
In this study we investigated whether the types of food people regularly eat are associated with how their thinking abilities change as they get older, Dr Blagojevic Castro said
The study also revealed that these associations did not appear across the entire cohort. Researchers noted that the accelerated mental decline emerged specifically among carriers of the APOE ε4 variant.
Our main finding was that among people carrying the APOE ε4 allele, greater adherence to a Western dietary pattern was associated with a faster decline in attention over time,
Dr Blagojevic Castro said. One of the most interesting findings was that the association with cognitive decline was not seen across the whole group but emerged specifically among APOE ε4 carriers.
We did not find significant associations between the healthier Prudent dietary pattern and cognitive decline, or between the Western dietary pattern and cognitive decline among people who did not carry APOE ε4,
said Dr Carolina Blagojevic Castro from Murdoch University’s Center for Healthy Ageing.
Broader Implications for Personalized Brain Health
Dr Blagojevic Castro said the findings reinforced growing evidence that the relationship between diet and brain health was complex and not the same for everyone.
What we eat may be one part of a much larger picture of healthy brain ageing,
she said.
The study emphasizes why research into individual differences is important. Dr Blagojevic Castro stated that approaches to protecting brain health may ultimately need to consider both lifestyle and biological factors rather than assuming that one approach will work equally well for everyone.
Investigators caution that because the study is observational, further research is needed before these findings can be translated into specific dietary recommendations based on genetic risk.
The project was supported by The University of Western Australia, Macquarie University, Edith Cowan University, the University of Sydney, and Brazil’s State University of Bahia.
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