It Is Never Too Late: A Systematic Review of Lifestyle Interventions for Cognitive Preservation in the Oldest-Old
By Ellen Feldman, MD
Altru Health System, Grand Forks, ND
SYNOPSIS: This systematic review reveals the importance of a healthy diet rich in fruits and vegetables, along with regular leisure and physical activities, to maintain cognitive functioning in the oldest-old, individuals older than 80 years of age.
SOURCE: Xinhong Ye K, Sun L, Wang L, et al. The role of lifestyle factors in cognitive health and dementia in oldest-old: A systematic review. Neurosci Biobehav Rev 2023;152:105286.
While there is no known cure for dementia, research strongly suggests that maintaining a healthy lifestyle during middle age can help prevent or slow cognitive decline in later years.1 Expanding on this, Xinhong Ye et al conducted a comprehensive review of studies focusing on modifiable lifestyle factors among the oldest-old, defined for this study as individuals aged 80 years or older at baseline. This research aims to identify effective interventions for preventing cognitive impairment in this rapidly growing age group.
The review included a total of 27 studies. Most of these studies (17) were conducted in Asia, with eight from Europe and two from the United States. The majority of these were longitudinal studies; none were randomized controlled trials. Some studies examined multiple lifestyle factors simultaneously, while others focused on individual factors. Methodology and outcome measures varied across the group.
Eleven studies focused on nutrition and diet, with most finding that a diet high in fruits and vegetables and a diverse diet both were associated with a lower risk of cognitive impairment and/or decline. Interestingly, even switching to a more varied diet later in life seems to offer some protection. Among individual food groups, only legume and bean consumption were consistently associated with reduced cognitive decline.
Ten studies examined physical exercise. Seven of these studies found a link between higher levels of physical activity and reduced odds of cognitive impairment. One study identified this association only in men, another only in women, and a third found no association between physical activity and dementia.
Eight studies examined leisure activities. All but one of these studies found an association between greater involvement in social or mentally stimulating activities (such as playing cards, reading, tending to domestic animals, socializing, and travel) and a lower risk of cognitive impairment.
Five studies explored the effect of smoking. Two of these studies found an association between smoking and greater odds of cognitive impairment, while three of the studies did not show any association between smoking and cognitive impairment.
Four studies looked at alcohol consumption. One study connected minimal alcohol use with lower scores on a mini-mental status examination, while the remainder found no connection between alcohol use and cognitive status.
Two studies found that respondents with overall healthier lifestyles had reduced odds of cognitive impairment and more years without cognitive impairment compared with peers with unhealthy lifestyles.
One study found that being a carrier of the APOE ε4 allele (a known risk factor for Alzheimer’s dementia) did not affect the association between lifestyle factors and cognitive impairment.
Who are the oldest-old? According to the World Health Organization and the American Geriatrics Society, old age can be divided into three distinct groups, the young-old, the middle-old, and the oldest-old.2 The cutoff age for the oldest-old can vary slightly depending on the region, but it generally refers to individuals older than 80 years of age. This demographic is expanding rapidly and is projected to triple, reaching approximately 446 million people worldwide over the next 30 years. Proactively addressing the medical needs of this age group is crucial, as it can lead to public health benefits, such as improved quality of life, reduced healthcare costs, and enhanced overall well-being for this growing segment of the population.2,3
Commentary
Xinhong Ye et al bring much-needed rigor to this field by conducting a systematic review of lifestyle factors affecting cognitive functioning in the oldest-old. The fact that they identified only 27 eligible studies highlights the urgent need for more research in this area.
A major challenge in comparing and drawing conclusions from these studies was the diversity in methodology and outcome measures. For example, some studies measured cognitive decline using self-administered tools, others conducted clinical interviews, while some relied on electronic medical records. Large-scale investigations of this age group, with globally standardized outcome measures and tools, would enhance confidence in the conclusions drawn.
The reviewed articles studied five major lifestyle interventions: nutrition and diet, physical activity, leisure pursuits, smoking, and alcohol use.
Nutrition: The finding that diets high in fruits and vegetables are associated with reduced cognitive decline aligns with previous meta-analysis.4 This correlation may be partly explained by recent imaging studies suggesting that higher vegetable consumption is linked to favorable structural changes in the brain.5
Dietary diversity, a significant concern for the older adults because of problems such as swallowing difficulties and financial constraints, also appeared beneficial, possibly because less-varied diets increase the risk of nutritional deficiencies.6 Finally, the finding that legumes and beans may be protective against cognitive decline could have to do with the high protein content of these items as well as other factors.
Physical Activity: It is not surprising that increasing levels of physical activity in the oldest-old are associated with decreased cognitive impairment. Research has shown that physical activity leads to favorable structural and neurochemical changes in the brain and protects against cardiovascular and other illnesses that can predispose individuals to decreased cognitive functioning.7
The finding in a few studies that limited the benefits to either men or women (or found no benefit) may be related to small sample size, highlighting the need to continue to refine research in this area.
Leisure Activity: Most studies indicated an association between pleasurable activities and reduced cognitive impairment. Ongoing research suggests that this may be because of the reduction of stress hormones during positive emotional states.8
Smoking and Alcohol Consumption: The findings in this area were among the more surprising from this review. While both smoking and alcohol consumption are considered risk factors for the development of dementia, in the oldest-old, they did not seem to correlate with a higher risk of cognitive impairment in most studies.9 More investigations focusing on this age group are warranted before providing recommendations.
There is growing evidence that a healthy lifestyle in general may protect against cognitive decline. Unfortunately, only two studies in this review looked at a combination of lifestyle factors, making it difficult to generalize findings. One study examined the impact of APOE status and found that a healthy lifestyle was associated with less cognitive decline regardless of APOE status, consistent with some findings in younger populations.1 However, more studies are necessary to draw definitive conclusions.
This systematic review underscores the importance of lifestyle factors in the cognitive health of the oldest-old. For the internal medicine provider, these findings highlight the potential benefits of promoting a healthy diet, encouraging physical activity, and encouraging engaging in enjoyable activities to help maintain cognitive functioning in older adult patients.
While the relationship between smoking and alcohol consumption and cognitive health in the oldest-old remains inconclusive, these findings highlight the need for continued research to develop targeted interventions for this age group.
References
- Jia J, Zhao T, Liu Z, et al. Association between healthy lifestyle and memory decline in older adults: 10 year, population based, prospective cohort study. BMJ 2023;380:e072691.
- Escourrou E, Laurent S, Leroux J, et al. The shift from old age to very old age: An analysis of the perception of aging. BMC Prim Care 2022;23:3.
- World Health Organization. Ageing and health. Oct. 1, 2022. https://www.who.int/news-room/fact-sheets/detail/ageing-and-health
- Smyth A, Dehghan M, O’Donnell M, et al; ONTARGET and TRANSCEND Investigators. Healthy eating and reduced risk of cognitive decline: A cohort from 40 countries. Neurology 2015;84:2258-2265.
- Townsend RF, Woodside JV, Prinelli F, et al. Associations between dietary patterns and neuroimaging markers: A systematic review. Front Nutr 2022;9:806006.
- Otsuka R, Tange C, Nishita Y, et al. Dietary diversity and all-cause and cause-specific mortality in Japanese community-dwelling older adults. Nutrients 2020;12:1052.
- Vecchio LM, Meng Y, Xhima K, et al. The neuroprotective effects of exercise: Maintaining a healthy brain throughout aging. Brain Plast 2018;4:17-52.
- Su S, Shi L, Zheng Y, et al. Leisure activities and the risk of dementia: A systematic review and meta-analysis. Neurology 2022;99:e1651-1663.
- Zhou S, Zhou R, Zhong T, et al. Association of smoking and alcohol drinking with dementia risk among elderly men in China. Curr Alzheimer Res 2014;11:899-907.
This systematic review reveals the importance of a healthy diet rich in fruits and vegetables, along with regular leisure and physical activities, to maintain cognitive functioning in the oldest-old, individuals older than 80 years of age.
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