In last month’s issue of the British Journal of Community Nursing, we delved into the impact of diet on cognitive decline (Mendes, 2023). Nutrition is a severely underrated factor in disease; however, it is not the only factor and a generally healthy lifestyle, including and beyond nutrition, is essential to strive for in both the prevention and treatment of illness and, in this case, cognitive decline.
A recent study carried out by Jia et al (2023) and published in the British Medical Journal (BMJ) looked at an overall healthy lifestyle (including nutrition) and how this might be associated with memory decline in older adults. The aim of the study was to identify the optimal lifestyle profile associated with retaining good cognition into older age. This prospective cohort study examined Chinese participants aged 60 years or over, who started the study with normal cognition and also had undergone apolipoprotein E (APOE) genotyping at baseline in 2009. Participants were then followed up regularly until they died, discontinued the study, or when the study came to an end on 26 December 2019.
Healthy lifestyle factors
Jia et al (2023) assessed the below six healthy lifestyle factors:
- Healthy diet (adherence to the recommended intake of at least seven of eligible food items)
- Regular physical exercise (≥150 minutes of moderate intensity or ≥75 minutes of vigorous intensity, per week)
- Active social contact (≥twice per week)
- Active cognitive activity (≥twice per week)
- Never or previously smoked
- Never drinking alcohol.
If clients had four to six of the healthy lifestyle factors, they were part of the ‘favourable’ group. If they had two to three of these factors, they were considered part of the ‘average’ group, and if none or only one of the above factors was present in their life, they were part of the ‘unfavourable’ group. Memory function was assessed using the World Health Organization/University of California-Los Angeles AuditoryVerbal Learning Test, and global cognition was assessed via the Mini-Mental State Examination.
Diet
A person’s diet was deemed healthy if they consumed the recommended amounts of at least seven of the following food groups: fruits, vegetables, fish, meat, dairy, salt, oil, eggs, cereals, legumes, nuts and tea based on dietary guidelines produced by the Chinese Nutrition Society (2016). The main messages of these guidelines are as follows (2016):
- Eat a variety of foods
- Balance eating and exercise to maintain a healthy body weight
- Consume plenty of vegetables, milk and soybeans
- Consume an appropriate amount of fish, poultry, eggs and lean meat
- Reduce oil and salt, and limit alcohol and sugar
- Eliminate waste and develop a new ethos of diet civilisation.
Pointing again to the important role of diet, another relatively recent prospective cohort study concluded that eating behaviours can delay the onset of dementia by as much as several years (Jennings et al, 2020).
Exercise
The American guidelines for physical activity in adults were used as a benchmark for physical activity in this study, with both weekly frequency and total exercise time recorded. These guidelines recommend for adults to engage in at least 150–300 minutes every week of moderate-intensity aerobic physical activity, or 75–150 minutes per week of vigorous-intensity aerobic physical activity (or an equivalent combination) (Piercy et al, 2018). They also recommend strength training activities for the muscles on 2 or more days per week. Importantly, for older adults, the guidelines recommend what they call ‘multicomponent’ physical activity that includes balance training, as well as aerobic and musclestrengthening. In this study, at least 150 of moderate-intensity or 75 minutes of vigorous activity was considered a healthy factor (Piercy et al, 2018).
Social contact and cognitive activity
Social contact and cognitive activity, each twice a week, were considered favourable in this study. Social contact included participating in meetings, attending parties, visiting friends and relatives, whether in person or chatting online, and travelling. Activities classified as cognitive were writing, reading, and playing cards and other games.
Smoking and drinking
Never smoking or former smoking, and never drinking were both considered healthy lifestyle factors in this study. Participants were categorised according to whether they smoked currently, never smoked (which was defined as <100 cigarettes in their lifetime), or used to smoke (had quit smoking at least 3 years prior to the study). For alcohol consumption, participants were divided according to whether they never drank (or drank occasionally), low to excess drinking (daily consumption 1–60 grams), and heavy drinking (daily alcohol consumption of more than 60 grams).
Conclusions
Nearly 30000 people were included and the ratios of men to women were almost equal. The results showed significant impacts of the noted lifestyle factors. As might be expected, those in the favourable group achieved the best scores, and those in the unfavourable group achieved the worst scores.
It is worth noting that global and national dietary macronutrient (such as fat and carbohydrate) and food guidelines (eating fruits and vegetables and reducing salt intake) are aimed at managing cardiometabolic risk. However, cognitive function is linked to good heart health. Jennings et al (2020) therefore noted that good adherence to the current guidelines may still help the brain’s cognition but that it would be ideal to create new guidelines that consider reducing risk of dementia or improving mild cognitive decline. However, further research would be required to establish which strategies are best.
Nonetheless, it was clear from the results of Jia et al (2023) that a healthy lifestyle was associated with a slower rate of memory decline, even when in the presence of the allele responsible for higher chance of cognitive issues (APOE G4 allele).