Western diet linked to faster brain decline

A new study of 185 older adults found that people carrying the APOE ε4 gene, the strongest common genetic risk factor for Alzheimer's, showed faster decline in attention when following a Western-style diet.

What counts as a Western diet

The Western dietary pattern includes processed foods, refined grains, red and processed meats, fried foods and sugary products. The healthier Prudent pattern emphasizes fruits, vegetables, fish and whole grains.

The study tracked 57 APOE ε4 carriers

Among 185 participants followed for up to 7.5 years, 57 carried the APOE ε4 gene. Those who followed a Western diet showed faster attention decline, but the link weakened when researchers excluded people who may have had early cognitive problems.

No effect for people without the gene

The Western diet showed no significant link to cognitive decline in people who did not carry the APOE ε4 gene, and the healthier Prudent pattern showed no significant effects in any group.

Study cannot prove cause and effect

The research was observational, meaning it can identify associations but not establish whether diet actually caused the cognitive decline. Researchers also could not determine if changing diet later in life would help slow decline.

“The findings should therefore be considered hypothesis-generating, rather than evidence that diet modifies genetic risk for Alzheimer's disease.”

Experts caution against genetic testing

Lead researcher Dr. Carolina Blagojevic Castro said the findings do not provide enough evidence to support APOE genetic testing or personalized dietary recommendations. Anyone considering testing should consult with medical and genetic counselors.

“APOE ε4 is an important genetic risk factor for Alzheimer's disease, but it is not deterministic.”

Brain health requires multiple approaches

Research like the FINGER trial suggests protecting brain health requires a combination of dietary guidance, physical activity, cognitive training and management of vascular and metabolic risk factors, not just diet alone.

“Taken together, the evidence supports a multidomain view of cognitive aging rather than attributing risk or protection to a single food or behavior.”

This study is a starting point, not a prescription

Independent expert Caghan Kizil noted the study had limitations including only 57 APOE ε4 carriers, diet measured once at the start, and participant dropout. He said the findings should prompt further research, not individual dietary changes.

“These findings give researchers a lead, not families a prescription.”