A 10-year study of Chinese adults over the age of 60, showed that a healthy lifestyle, in particular a nutritious diet, is associated with the slowing of memory decline in older people.
The major new research published in The BMJ, showed that the benefits of healthy living were even seen in those with a gene making them genetically susceptible to Alzheimer’s disease.
Carriers of the apolipoprotein E (APOE) gene—the strongest known risk factor for Alzheimer’s and related dementia—saw a slowing in memory loss associated with healthy habits, such as refraining from alcohol.
The Chinese research team said that memory continuously declines as people age, but evidence from existing studies was insufficient to assess the effect of a healthy lifestyle on memory in later life.
Given the many possible causes of memory decline, they explained that a combination of healthy behaviors might be needed for the best effect.
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The researchers analyzed data from 29,000 adults over 60 with normal cognitive function. The group had an average age of 72 and almost half were women.
At the start of the study in 2009, memory function was measured using an Auditory Verbal Learning test (AVLT) and participants were tested for the APOE gene; 20 percent were found to be carriers. Follow-up assessments were then conducted in 2012, 2014, 2016, and 2019.
A healthy lifestyle score combining six factors—diet, regular exercise, active social contact, cognitive activity (such as reading and writing), non-smoking, and never drinking alcohol—was then calculated.
Based on their score, ranging from zero to six, participants were put into favorable (four to six healthy factors), average (two or three), or unfavorable (one or zero) lifestyle groups—and separated into APOE carrier and non-carrier groups.
After taking into account other health, economic and social factors, the researchers found that each individual healthy behavior was associated with a slower than average decline in memory over 10 years.
“A healthy diet had the strongest effect on slowing memory decline, followed by cognitive activity and then physical exercise,” said study lead author Professor Jianping Jia.
“Compared with the group that had unfavorable lifestyles, memory decline in the favorable lifestyle group was 0.28 points slower over 10 years based on a standardized score of the AVLT, and memory decline in the average lifestyle group was 0.16 points slower.
“Participants with the APOE gene with favorable and average lifestyles also experienced a slower rate of memory decline than those with an unfavorable lifestyle.
“What’s more, those with favorable and average lifestyles were almost 90 percent and almost 30 percent less likely to develop dementia or mild cognitive impairment relative to those with an unfavorable lifestyle—and the APOE group had similar results.”
He said the research was observational so can’t establish cause, but it was a large study with a long follow-up period, allowing for evaluation of individual lifestyle factors on memory function over time.
The researchers say their results provide “strong evidence” that sticking to a healthy lifestyle with a combination of positive behaviors is associated with a slower rate of memory decline, even for people who are genetically susceptible to memory decline.