Adhering to six healthy lifestyle behaviors is linked to slower memory decline in older adults, a large population-based study suggests.
The researchers found that a healthy diet, cognitive activity, regular physical exercise, not smoking, and abstaining from alcohol were significantly associated with slower cognitive decline, regardless of APOE4 status.
After adjusting for health and socioeconomic factors, the researchers found that each individual healthy behavior was associated with slower-than-average memory decline over a decade. A healthy diet emerged as the strongest deterrent, followed by cognitive activity and physical exercise.
“A healthy lifestyle is associated with slower memory decline, even in the presence of the APOE4 allele,” study researchers led by Jianping Jia, MD, PhD, of the Innovation Center for Neurological Disorders and Department of Neurology, Xuan Wu Hospital, Capital Medical University, Beijing, China, write.
“This study could offer important information to protect older adults against memory decline,” they add.
The study was published online January 25 in The BMJ.
Prevention of memory decline
Memory “continuously declines as people age,” but age-related memory decline is not necessarily a prodrome of dementia and may “simply be senescent forgetfulness,” the researchers note. This can be “reversed or [can] stabilize”, rather than progressing to a pathological state.
Factors that affect memory include aging, APOE4 genotype, chronic disease, and lifestyle patterns, with lifestyle “receiving increasing attention as a modifiable behavior.”
However, few studies have focused on the impact of lifestyle on memory; and those that have are mostly cross-sectional and also “did not consider the interaction between a healthy lifestyle and genetic risk,” the researchers noted.
To investigate, the researchers conducted a longitudinal study, known as the China Aging and Cognition Study, which considered genetic risk and lifestyle factors.
The study began in 2009 and concluded in 2019. Participants were evaluated and underwent neuropsychological testing in 2012, 2014, 2016, and at the end of the study.
Participants (n = 29,072; mean [SD] age, 72.23 [6.61] years; 48.54% women; 20.43% carriers of APOE4) had to have a normal cognitive function at the beginning of the study. Data on those whose condition progressed to mild cognitive impairment (MCI) or dementia during the follow-up period were excluded after their diagnosis.
The Mini-Mental State Exam was used to assess global cognitive function. Memory function was assessed using the World Health Organization/University of California-Los Angeles auditory verbal learning test.
The “lifestyle” consisted of six modifiable factors:
Physical exercise (weekly frequency and total time)
Smoking (current, former or never smokers)
Alcohol use (never drank, drank occasionally, drank lightly to excessively, and drank excessively)
Diet (daily intake of 12 foods: fruits, vegetables, fish, meat, dairy products, salt, oil, eggs, cereals, legumes, nuts, tea)
Cognitive activity (writing, reading, playing cards, mahjong, other games)
Social contact (participate in meetings, attend parties, visit friends/family, travel, chat online)
The participants’ lifestyle was rated based on the number of healthy factors they participated in.
Lifestyle Number of healthy factors Number of participants Favorable 4 – 6 5556 Average 2 – 3 16,549 Unfavorable 1 – 2 6967
Participants were also stratified by APOE genotype into APOE4 carriers and non-carriers.
Demographics and other items of health information, including the presence of medical conditions, were used as covariates. The researchers also included the “learning effect of each participant as a covariate, due to repeated cognitive assessments.”
Important for public health
During the 10-year period, 7,164 participants died and 3,567 discontinued.
Participants in the favorable and average groups showed slower memory decline for each year of age (0.007 [0.005 – 0.009], p < 0.001; and 0.002 [0 .000 – 0.003]p = 0.033 points higher, respectively), compared to those in the unfavorable group.
The healthy diet had the greatest protective effect on memory.
Lifestyle factor β (95% CI) p value Healthy diet 0.016 (0.014 – 0.017) < 0.001 Active cognitive activity 0.010 (0.008 – 0.012) < 0.001 Regular physical exercise 0.007 (0.005 – 0.009) < 0.001 Active social contact 0.004 ( 0.002 – 0.006) < 0.001 Never/smoker 0.004 (0.000 – 0.008) = 0.026 Never drink 0.002 (0.000 – 0.004) = 0.048
Memory decline occurred faster in APOE4 operators than in non-APOE4 operators (0.002 points/year). [95% CI, 0.001 – 0.003]; p = 0.007).
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 a 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 limitations of the study, including its observational design and the potential for measurement error, due to self-reported lifestyle factors. In addition, some participants did not return for follow-up assessments, leading to possible selection bias.
Nonetheless, the findings “could offer important public health information to protect older people against memory decline,” they note, especially since the study “provides evidence that these effects also include people with APOE4 allele”.
“Important and encouraging” research
Commenting for Medscape Medical News, Severine Sabia, PhD, a senior researcher at Université Paris Cité, INSERM Institut National de la Santé et de la Recherche Medicalé, France, called the findings “important and encouraging.”
However, said Sabia, who was not involved in the study, “important research questions remain that need to be investigated to identify key behaviors, which combination, the risk threshold, and when to intervene.”
Future prevention research “should examine a broader range of potential risk factors” and should also “identify specific exposures associated with the highest risk, also considering the risk threshold and age of exposure for each.”
In an accompanying editorial, Sabia and co-author Archana Singh-Manoux, PhD, note that the risk of cognitive decline and dementia is likely determined by multiple factors.
They compare it to the “multifactorial risk paradigm introduced by the Framingham study,” which “led to a substantial reduction in cardiovascular disease.” A similar approach could be used with dementia prevention, they suggest.
The study was funded by the National Natural Science Foundation of China Key Project; the National Key Scientific Instruments and Equipment Development Project; the China National Natural Science Foundation Key Project; the Beijing Scholars Program; the Beijing Brain Initiative of the Beijing Municipal Science and Technology Commission; the CHINACANADA Joint Initiative on Alzheimer’s Disease and Related Disorders; the Mission Program of the Beijing Municipal Hospital Administration; National Natural Science Foundation of China; the National Science and Technology Foundation of China; the Beijing Natural Science Foundation; Major Project of the Beijing Municipal Science and Technology Commission; and the Navigation Plan of the Beijing Municipal Hospital Administration. The authors received support from 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. Sabia received a grant from the French National Research Agency. Singh-Manoux received grants from the National Institute on Aging of the National Institutes of Health.
BMJ. Published online January 25, 2023. Full Text, Editorial
Batya Swift Yasgur, MA, LSW, is a freelance writer with a consulting practice in Teaneck, New Jersey. She is a regular contributor to numerous medical journals, including Medscape and WebMD, and is the author of several consumer-oriented health books, as well as Behind the Burqa: Our Lives in Afghanistan and How We Escaped to Freedom (the memoirs of two brave Afghans). . sisters who told him her story).
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