Important for public health
During the 10-year period, 7,164 participants died, and 3,567 stopped participating.
Participants in the favorable and average groups showed slower memory decline per increased year of age (0.007 [0.005-0.009], P < .001; and 0.002 [0 .000-0.003], P = .033 points higher, respectively), compared with those in the unfavorable group.
Healthy diet had the strongest protective effect on memory.
Memory decline occurred faster in APOE4 vesus non-APOE4 carriers (0.002 points/year [95% confidence interval, 0.001-0.003]; P = .007).
But APOE4 carriers with favorable and average lifestyles showed slower memory decline (0.027 [0.023-0.031] and 0.014 [0.010-0.019], respectively), compared with those with unfavorable lifestyles. Similar findings were obtained in non-APOE4 carriers.
Those with favorable or average lifestyle were respectively almost 90% and 30% less likely to develop dementia or MCI, compared with those with an unfavorable lifestyle.
The authors acknowledge the study’s limitations, including its observational design and the potential for measurement errors, owing to self-reporting of lifestyle factors. Additionally, some participants did not return for follow-up evaluations, leading to potential selection bias.
Nevertheless, the findings “might offer important information for public health to protect older [people] against memory decline,” they note – especially since the study “provides evidence that these effects also include individuals with the APOE4 allele.”
‘Important, encouraging’ research
In a comment, Severine Sabia, PhD, a senior researcher at the Université Paris Cité, INSERM Institut National de la Santé et de la Recherche Medicalé, France, called the findings “important and encouraging.”
However, said Dr. Sabia, who was not involved with the study, “there remain important research questions that need to be investigated in order to identify key behaviors: which combination, the cutoff of risk, and when to intervene.”
Future research on prevention “should examine a wider range of possible risk factors” and should also “identify specific exposures associated with the greatest risk, while also considering the risk threshold and age at exposure for each one.”
In an accompanying editorial, Dr. Sabia and co-author Archana Singh-Manoux, PhD, note that the risk of cognitive decline and dementia are probably determined by multiple factors.
They liken it to the “multifactorial risk paradigm introduced by the Framingham study,” which has “led to a substantial reduction in cardiovascular disease.” A similar approach could be used with dementia prevention, they suggest.
The authors received support from the Xuanwu Hospital of Capital Medical University for the submitted work. One of the authors received a grant from the French National Research Agency. The other authors have disclosed no relevant financial relationships. Dr. Sabia received grant funding from the French National Research Agency. Dr. Singh-Manoux received grants from the National Institute on Aging of the National Institutes of Health.
A version of this article first appeared on Medscape.com.