Healthy lifestyle choices slowed memory decline in older adults, including those with a genetic predisposition, according to study findings published in BMJ.
Studies have revealed that genetic expression of apolipoprotein E (APOE) ε4 increases the risk for memory decline. However, longitudinal studies have not yet been done to assess the effect of lifestyle modifications on memory decline, particularly in people who are genetically more susceptible to memory decline.
To assess the effect of healthy lifestyle factors on memory decline, researchers in China conducted a 10-year, nationwide, population-based, prospective, cohort study across 12 provinces and 96 sites throughout the country using data from the China Cognition and Aging Study (COAST) on dementia. They included 29,072 participants (48.54% women; mean Standard Deviation [SD] age, 72.23 [6.61] years; 20.43% APOE ε4 carriers) who had undergone APOE genotyping for their study in May 2009.
After enrollment, the researchers followed these participants until death, discontinuation of the study, or December 26, 2019. Four rounds of follow-ups were conducted in 2012, 2014, 2016, and 2019. To assess global cognitive function, the researchers used the Mini-Mental State Examination. For memory function assessment, they relied on the World Health Organization/University of California- Los Angeles Auditory Verbal Learning Test (AVLT).
Six categories of lifestyle factors were evaluated, including diet, physical activity, social contact, cognitive activity, smoking status, and consumption of alcohol. Healthy diet involved adherence to recommended intake of at least 7 of 12 eligible food items, including fruit, vegetables, fish, meat, dairy products, salt, oil, eggs, cereal, legumes, nuts, and tea. Healthy physical activity consisted of 150 or more minutes of moderate intensity exercise or 75 or more minutes of vigorous intensity exercise per week. Healthy social contact required connection with other people twice or more per week. Healthy cognitive activity involved reading, writing, and playing cards or other games twice or more per week. The researchers classified current abstinence from both smoking and alcohol as healthy behavior.
Based on these 6 categories, the researchers separated the participants into either favorable/healthy, average, or unfavorable/unhealthy lifestyle groups.
Over time, according to AVLT results, people in the favorable group demonstrated significantly slower memory decline than those in the unfavorable group (difference in AVLT points per year: 0.028; 95% CI, 0.023-0.032; P <.001).
When analyzing lifestyle choices strictly among APOE ε4 carriers, the researchers observed that carriers with favorable or average lifestyles demonstrated slower memory decline compared with carriers with unfavorable lifestyles (difference in points per year- favorable vs. unfavorable: 0.027; 95% CI, 0.023-0.031; P <.001; average vs. unfavorable: 0.014; 95% CI, 0.010-0.019).
This trend of slower memory decline in the favorable and average lifestyle groups compared with the unfavorable group manifested similarly in non-APOE carriers (favorable vs. unfavorable: 0.029; 95% CI, 0.019-0.039; average vs. unfavorable: 0.019; 95% CI, 0.011-0.027).
Healthy and average lifestyles were found to reduce risk for mild cognitive decline and dementia compared with unhealthy lifestyles (hazard ratio [HR] for healthy vs unhealthy lifestyles, 0.11; 95% CI, 0.10-0.12; HR for average vs unhealthy lifestyles: 0.71; 95% CI, 0.68-0.73).
“Importantly, our study provides evidence that these effects also include individuals with the APOE ε4 allele,” the researchers noted. They concluded, “These results might offer important information for public health initiatives to protect older adults against memory decline.”
Study limitations included participant-reported outcome measures prone to recall bias and measurement errors, missing data and participant drop-out rate leading to selection bias, possibility of decreased participation of unhealthy people in the study, and lack of assessment of the influence of healthy lifestyle on cognition prior to study initiation. Additional limitations included use of a single neuropsychological test to determine memory decline and the possibility of the learning effect due to repeated testing influencing results.
Jia J, Zhao T, Liu Z, et al. Association between healthy lifestyle and memory decline in older adults: 10 year, population based, prospective cohort study. BMJ. Published online January 25, 2023. doi:10.1136/bmj-2022-072691