Causality Versus Connection
Commenting on the findings, Rebecca M. Edelmayer, PhD, senior director of scientific engagement for the Alzheimer’s Association, cautioned that the study was designed to show correlation, not causation.
Other notable limitations include measuring prevalence or incidence of dementia from death records because dementia and Alzheimer’s disease are often underreported as a cause of death.
Moreover, people in the highest olive oil consumption group also had better diet quality, higher alcohol intake, were more physically active, and less likely to smoke, Dr. Edelmayer said.
“All of these factors may have an impact on risk of cognitive decline and dementia, separately from or in addition to olive oil consumption,” said Dr. Edelmayer, who was not involved with the study.
She echoed the authors’ concerns that the study was conducted in predominantly non-Hispanic White people and noted that the protective benefits of olive oil were no longer statistically significant for men after adjusting for potential confounders.
It “would be wonderful if a particular food could delay or prevent Alzheimer’s disease, but we do not have scientific evidence that these claims are true,” Dr. Edelmayer said. “We need randomized controlled clinical trials to evaluate whether any foods have a scientifically proven beneficial effect.”
This study is supported by a research grant from the National Institutes of Health to the senior author. The NHS, NHSII, and HPFS are supported by grants from the National Institutes of Health. Tessier is supported by the Canadian Institutes of Health Research Postdoctoral Fellowship Award. Senior author Guasch-Ferré is supported by a Novo Nordisk Foundation grant. Dr. Tessier reported no other relevant financial relationships. The other authors’ disclosures are listed on the original paper. Dr. Edelmayer reported no relevant financial relationships.
A version of this article appeared on Medscape.com.