Elderly people with a genetic risk for Alzheimer’s disease did not experience the expected increase in cognitive decline and dementia risk if they ate relatively large amounts of meat. This is shown in a new study from the Karolinska Institutet published in JAMA Network Open. The results may contribute to the development of more personalized nutritional advice.
APOE is a gene that affects the risk of Alzheimer’s disease. In Sweden, about 30 percent of the population are carriers of the APOE 3/4 or APOE 4/4 gene combinations. Among people with Alzheimer’s disease, people with these genotypes account for nearly 70 percent.
When the Swedish Food Agency presented an overview of research on the link between diet and dementia last year, more research was called for to assess a possible link between meat consumption and the development of dementia.
This study tested the hypothesis that people with APOE 3/4 and 4/4 would have a reduced risk of cognitive decline and dementia with higher meat intake, based on the fact that APOE4 is the evolutionarily oldest variant of the APOE gene and may have arisen at a time when our evolutionary ancestors followed a more sedentary diet.
Jakob Norgren, first author, researcher, Department of Neurobiology, Care and Social Sciences, Karolinska Institutet
The study followed more than 2,100 participants in the Swedish National Study on Aging and Care, Kungsholmen (SNAC-K) for up to 15 years. All were aged 60 years or older and did not have a diagnosis of dementia at the start of the study. The association between self-reported diet and measures of cognitive health was analyzed, adjusting for age, sex, education and lifestyle factors.
At lower meat intake, the group with APOE 3/4 and 4/4 had more than twice the risk of dementia than people without these gene variants. However, the increased risk of cognitive decline and dementia in the risk groups was not seen in the fifth of participants who ate the most meat. Their average consumption is estimated at around 870 grams of meat per week, standardized to a daily energy intake of 2,000 calories.
“Those who ate more meat overall had significantly slower cognitive decline and a lower risk of dementia, but only if they had the APOE gene variants 3/4 or 4/4,” says Jakob Norgren. He continues:
“There is a dearth of nutritional research on brain health, and our findings suggest that conventional dietary advice may be unfavorable to a genetically determined subgroup of the population. For those who know they are in this genetic risk group, the findings offer hope. the risk may be modifiable through lifestyle changes. ‘
The study also shows that the type of meat is important.
“A lower proportion of processed meat in total meat consumption was associated with a lower risk of dementia regardless of APOE genotype,” says Sara Garcia-Ptacek, an assistant professor in the same department who, along with senior lecturer Erika J Laukka, is the final author of the study.
The findings also extend beyond brain health. In a follow-up analysis, researchers observed a significant reduction in all-cause mortality in APOE 3/4 and 4/4 carriers with higher unprocessed meat consumption.
However, the study is observational and needs to be followed up with intervention studies that can better demonstrate causal relationships.
“Clinical trials are now needed to develop nutritional recommendations tailored to the APOE genotype,” says Jakob Norgren. He continues:
“Given that the prevalence of APOE4 is approximately twice as high in Nordic countries as in Mediterranean countries, we are particularly well-suited to conduct research on tailored dietary recommendations for this risk group.”
The research was funded by, among others, the Swedish Alzheimer Foundation, the Swedish Dementia Foundation, the Emil and Wera Cornell Foundation, the Leif Lundblad family and other philanthropists, the Swedish Research Council and FORTE.
