A healthy lifestyle is associated with slower memory decline, even in the presence of the APOE ε4 allele. This study might offer important information to protect older adults against memory decline.
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"Lifestyle" consisted of six modifiable factors:
Physical exercise (weekly frequency and total time)
Smoking (current, former, or never-smokers)
Alcohol consumption (never drank, drank occasionally, low to excess drinking, and heavy drinking)
Diet (daily intake of 12 food items: fruits, vegetables, fish, meat, dairy products, salt, oil, eggs, cereals, legumes, nuts, tea)
Cognitive activity (writing, reading, playing cards, mahjong, other games)
Social contact (participating in meetings, attending parties, visiting friends/relatives, traveling, chatting online)
Participants' lifestyle was scored on the basis of the number of healthy factors they engaged in.
Participants were also stratified by APOE genotype into APOE4 carriers and noncarriers.
Demographic and other items of health information, including the presence of medical illness, were used as covariates. The researchers also included the "learning effect of each participant as a covariate, due to repeated cognitive assessments."
During the 10-year period, 7164 participants died, and 3567 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 to those in the unfavorable group.
Healthy diet had the strongest protective effect on memory.
Memory decline occurred faster in APOE4 vs non-APOE4 carriers (0.002 points/year [95% CI, 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 to 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 to 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 against memory decline," they note — especially since the study "provides evidence that these effects also include individuals with the APOE4 allele."