Memory Decline Tied to Lifestyle Factors

Memory decline was slower for older adults who had a healthy lifestyle, even for people with high genetic risk for Alzheimer’s disease, data from a Chinese study showed.

People 60 and older who had at least four of six favorable lifestyle factors — healthy diet, exercise, social contact, cognitive activity, and no smoking or drinking — had slower memory decline than those who had no more than one healthy factor, according to Jianping Jia, MD, PhD, of Xuanwu Hospital of Capital Medical University in Beijing, and co-authors.

Over 10 years, memory decline was 0.28 points less on the Auditory Verbal Learning Test (AVLT) in the favorable lifestyle group compared with the unfavorable group (0.028 points/year, 95% CI 0.023-0.032, P<0.001), Jia and co-authors reported in The BMJ.

People who carried the apolipoprotein E ε4 (APOE4) allele also had slower memory decline with a favorable lifestyle (0.027 points/year, 95% CI 0.023-0.031) or an average lifestyle with two or three healthy factors (0.014 points/year, 95% CI 0.010-0.019), compared with an unfavorable one. Similar results were seen for non-APOE4 carriers.

“APOE4 is the strongest known risk factor for Alzheimer’s disease and related dementias, and within the context of ongoing and future targeted prevention trials, this outcome is particularly important,” noted Séverine Sabia, PhD, of Université de Paris, and Archana Singh-Manoux, PhD, of University College London, in an accompanying editorial.

“These results support the notion that lifestyle change might counteract the deleterious effect of APOE4 on cognitive decline and dementia,” Sabia and Singh-Manoux added.

Previous research has shown that APOE4 affects cognitive decline, but it does not negate all the benefits of a healthy lifestyle. In the U.S., healthy lifestyle scores in midlife have been associated with better cognition in later years, even among APOE4 carriers. And in the FINGER trial, APOE4 carriers who participated in an intervention comprising diet, exercise, cognitive training, and vascular risk management performed better than controls on annual cognitive tests.

Jia and co-authors analyzed data for 29,072 adults in the COAST study who initially tested normal for cognitive function. Mean age was about 72; 48.5% in the cohort were women, and 20.4% were APOE4 carriers.

At baseline in 2009, participants completed the AVLT; they had assessments again in 2012, 2014, 2016, and 2019. Lifestyle scores and health-related covariates also were determined at baseline and each follow-up visit.

The AVLT measured immediate recall, short-delay and long-delay recall, and long-delay recognition. Scores of immediate recall range from 0-60, while scores of all other tests range from 0-15. The researchers constructed a composite z score for memory function by averaging z scores for each part of the AVLT.

Of the six healthy lifestyle components, diet had the strongest association with memory (β 0.016, 95% CI 0.014-0.017, P<0.001), followed by cognitive activity, physical exercise, and social contact.

“Although each lifestyle factor contributed differentially to slowing memory decline, our results showed that participants who maintained more healthy lifestyle factors had a significantly slower memory decline than those with fewer healthy lifestyle factors,” Jia and co-authors wrote. “This information could be useful in making personal choices that can help to protect against memory decline, and our results provide further evidence that memory loss is potentially modifiable.”

Cognitive decline is likely influenced by several variables, Sabia and Singh-Manoux observed.

“The multifactorial risk paradigm introduced by the Framingham study has led to a substantial reduction in cardiovascular disease,” they pointed out. “A similar approach should be taken with dementia prevention, identifying not only the factors that matter most but also the threshold at which they matter, and the age when intervention is likely to be most effective, as the World Health Organization underlined in its recent report on brain health.”

The study has several limitations, Jia and colleagues acknowledged. Lifestyle factors were based on self-reported data. In addition, memory was assessed with one test only — a test that doesn’t comprehensively reflect overall memory function, the researchers noted.

“However, the Auditory Verbal Learning Test is an effective instrument for memory assessment, and we used a composite score based on four Auditory Verbal Learning Test subscales to represent memory conditions to the greatest extent possible,” they wrote.