A decade-long research of senior citizens in China, which was published today in The BMJ, shows that living a healthy lifestyle, especially eating a nutritious diet, is linked to a slower rate of memory loss.
A healthy lifestyle was found to reduce memory loss even in people who had the apolipoprotein E (APOE) gene, the strongest known risk factor for Alzheimer’s disease and related dementias.
Although evidence from past studies is insufficient to determine the impact of a healthy lifestyle on memory in later life, memory degrades steadily as people age. Given the wide range of potential reasons of memory loss, a combination of healthy behaviours might be required for the best results.
Researchers examined data from 29,000 persons with normal cognitive function who were enrolled in the China Cognition and Aging Study and were at least 60 years old (average age: 72; 49% women).
The Auditory Verbal Learning Test (AVLT) was used to assess participants’ memory performance at the beginning of the study in 2009, and 20% of individuals were found to be APOE gene carriers. The following decade saw follow-up evaluations in 2012, 2014, 2016, and 2019.
The results were then used to calculate a score for a healthy lifestyle that took into account six different factors: a balanced diet, regular exercise, active social contact (such as seeing friends and family), cognitive activity (such as writing, reading, or playing mahjong), not smoking, and never drinking alcohol.
Participants were divided into favourable (4 to 6 healthy factors), ordinary (2 to 3 healthy factors), or unfavourable (0 to 1 healthy factors) lifestyle groups as well as into APOE carrier and non-carrier groups based on their score, which ranged from 0 to 6.
After taking into account a variety of additional physiological, social, and economic variables, the researchers discovered that each individual healthy behaviour was connected to a slower than average deterioration in memory over the course of ten years.
The three factors that had the biggest impact on memory deterioration were a good diet, cognitive activity, and physical exercise.
Based on a standardised score (z score) of the AVLT, memory deterioration in the group with a favourable lifestyle was 0.28 points slower over 10 years compared to the group with an unfavourable lifestyle, while memory decline in the group with an average lifestyle was 0.16 points slower.
Additionally, persons with the APOE gene who led healthy, balanced lives had slower rates of memory loss than those who had unhealthy lives (0.027 and 0.014 points per year slower, respectively).
Additionally, compared to individuals who led unfavourable lives, those with favourable or normal lifestyles were respectively 90% and 30% less likely to get dementia or mild cognitive impairment. The APOE group also experienced similar outcomes.
Since this is an observational study, there is no way to determine the exact cause. The researchers are aware of some limitations, including the potential for measurement errors due to self-reporting of lifestyle factors and the potential for bias in selection because some participants did not return for further assessments.
However, due to the size of the study and the length of the follow-up period, it was possible to assess the long-term effects of various lifestyle factors on memory function. Additionally, results remained significant following several studies, indicating that they are reliable.
As a result, even for those who are genetically predisposed to memory decline, the researchers claim that their findings give compelling evidence that maintaining a healthy lifestyle with a variety of good behaviours is connected with a slower rate of memory deterioration.
In light of the fact that memory issues can also impact younger people, who were not included in this study, they propose that future research concentrate on the implications of a healthy lifestyle on memory deterioration across the lifetime. They write in their conclusion, “These results might provide valuable information for public health programmes to safeguard older persons from memory deterioration.”
Researchers state in a related editorial that “prevention is vital, considering the lack of viable treatments for Alzheimer’s disease and associated dementias.”
They do, however, draw attention to the fact that these findings are not helpful in identifying which of the six health behaviours included in the score (or particular combination) is the best target for preventing dementia or the optimal time in the life course to concentrate preventative efforts. They continue by saying that further knowledge is required to decide whether the variations in memory impairment seen in this study have clinical significance.
They propose that dementia prevention should follow a similar strategy that significantly reduced cardiovascular disease by “finding not only the characteristics that matter most but also the threshold at which they matter, and the age when intervention is expected to be most successful.”