Healthy lifestyle keeps memory decline at bay in older adults

Older adults who follow a healthy lifestyle tend to have better memory retention, even in the presence of the apolipoprotein E (APOE) ε4 allele, a study has found.

“The results of this study provide strong evidence that adherence to a healthy lifestyle with a combination of positive behaviours, such as never or former smoking, never drinking, a healthy diet, regular physical exercise, and active cognitive activity and social contact, is associated with a slower rate of memory decline,” the researchers said.

“Importantly, our study provides evidence that these effects also include individuals with the APOE ε4 allele,” they added.

The researchers conducted this population-based, prospective cohort study in China and included 29,072 individuals (mean age of 72.23 years, 48.54 percent were women, and 20.43 percent were APOE ε4 carriers) who had normal cognition and underwent APOE genotyping at baseline in 2009. They followed the participants until death, discontinuation, or 26 December 2019.

The following healthy lifestyle factors were evaluated: a healthy diet (adherence to the recommended intake of at least 7 of 12 eligible food items), regular physical exercise (≥150 min of moderate intensity or ≥75 min of vigorous intensity, per week), active social contact (≥twice per week), active cognitive activity (≥twice per week), never or previously smoked, and never drinking alcohol.

The researchers categorized participants into the favourable group if they met four to six healthy lifestyle factors, into the average group for two to three factors, and into the unfavourable group for zero to one factor.

The World Health Organization/University of California-Los Angeles Auditory Verbal Learning Test and the Mini-Mental State Examination were used to assess memory function and global cognition, respectively. Finally, the researchers explored the impact of lifestyle factors on memory using linear mixed models.

Memory decline was slower among participants in the favourable group than those in the unfavourable group (0.028 points/year, 95 percent confidence interval [CI], 0.023‒0.032; p<0.001) over 10 years of follow-up (2009‒2019). [BMJ 2023;380:e072691]

APOE ε4 carriers in the favourable (0.027 points/year, 95 percent CI, 0.023‒0.031) and average (0.014 points/year, 95 percent CI, 0.010 to 0.019) lifestyle groups also displayed a slower memory decline compared to those in the unfavourable group. Results were similar among noncarriers of APOE ε4 (favourable vs unfavourable group: 0.029 points/year, 95 percent CI, 0.019‒0.039; average vs unfavourable group: 0.019 points/year, 95 percent CI, 0.011‒0.027).

Notably, APOE ε4 status and lifestyle profiles showed no significant interaction impact on memory decline (p=0.52).

The mechanisms responsible for the beneficial effect of a healthy lifestyle on memory were not explored in this study but might include reduced cerebrovascular risk, enhancement of cognitive reserve, inhibition of oxidative stress and inflammation, and promotion of neurotrophic factors. [Prev Med 2009;48:86-90; Neuroepidemiology 2008;31:39-47; Neurology 2020;95:e374-383; PLoS Med 2017;14:e1002259]

“These results might offer important information for public health initiatives to protect older adults against memory decline,” the researchers said.