Investigators found that a healthy diet, cognitive activity, regular physical exercise, not smoking, and abstaining from alcohol were significantly linked to slowed cognitive decline irrespective of APOE4 status.
After adjusting for health and socioeconomic factors, investigators found that each individual healthy behavior was associated with a slower-than-average decline in memory 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 investigators led by Jianping Jia, MD, PhD, of the Innovation Center for Neurological Disorders and the department of neurology, Xuan Wu Hospital, Capital Medical University, Beijing, write.
“This study might offer important information to protect older adults against memory decline,” they add.
The study was published online in the BMJ.
Preventing memory decline
Memory “continuously declines as people age,” but age-related memory decline is not necessarily a prodrome of dementia and can “merely be senescent forgetfulness,” the investigators note. This can be “reversed or [can] become stable,” instead of progressing to a pathologic state.
Factors affecting memory include aging, APOE4 genotype, chronic diseases, and lifestyle patterns, with lifestyle “receiving increasing attention as a modifiable behavior.”
Nevertheless, 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 note.
To investigate, the researchers conducted a longitudinal study, known as the China Cognition and Aging Study, that considered genetic risk as well as 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 study’s conclusion.
Participants (n = 29,072; mean [SD] age, 72.23 [6.61] years; 48.54% women; 20.43% APOE4 carriers) were required to have normal cognitive function at baseline. 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 Examination 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.
“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), and social contact (participating in meetings, attending parties, visiting friends/relatives, traveling, chatting online).
Participants’ lifestyles were 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.”