A common Alzheimer’s risk gene may make the brain more vulnerable to a diet heavy in pizza, processed meat, and sweets.
Researchers led by Murdoch University and Alzheimer’s Research Australia followed 185 older adults in Perth for more than seven years. They found that participants who carried the APOE ε4 allele and ate more Western-style foods tended to lose attention skills faster. The same association did not appear among participants without that allele.
“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.
Two Diets, Different Patterns
Using data from the Western Australia Memory Study (WAMS), the team identified two broad eating patterns. The Western diet (unhealthy diet) included foods such as red and processed meat, chips, pizza, sweets, refined grains, and beer. The prudent diet (healthy diet) included fruit, vegetables, leafy greens, garlic, and whole grains.
None of the participants had diagnosed dementia when the study began. Researchers assessed their genetic susceptibility, including apolipoprotein E (APOE), and tested their thinking skills repeatedly over the following years. The tests covered attention, memory, executive function, language, recognition memory, and overall cognitive ability.
APOE ε4 is the strongest common genetic risk factor for Alzheimer’s disease. It gave the researchers a way to examine whether the relationship between diet and cognitive change varied by genetic risk.
The Link Appeared In APOE ε4 Carriers
“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.”
What the Findings Can and Cannot Show
Dr. Blagojevic Castro said the results add to evidence that diet and brain health are connected in ways that may depend on a person’s genetic makeup.
“What we eat may be one part of a much larger picture of healthy brain aging,” Dr. Blagojevic Castro said.
“Our findings highlight why research into individual differences is important—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.”
“However, our study is observational, so further research is needed before these findings can be translated into specific dietary recommendations based on genetic risk.”
Reference: “Dietary Patterns and Cognitive Decline in Older Adults: Findings from the Western Australia Memory Study” by Carolina Blagojevic Castro, Samantha L. Gardener, Farzana Jahan, Juliana Chen, Belinda M. Brown, Ruey L. Loo, Kevin Taddei, Stephanie R. Rainey-Smith, Michael Weinborn, Ana Caroline R. dos Reis, Manohar L. Garg, Ralph N. Martins and Hamid R. Sohrabi, 6 August 2026, Nutrients.
DOI: 10.3390/nu18162592
The study was supported by the University of Western Australia, Macquarie University, Edith Cowan University, the University of Sydney, Brazil’s State University of Bahia, the Department of Jobs, Tourism, Science and Innovation, and the Government of Western Australia through the Premier’s Science Fellowship Program.
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