Abstract
In 1948, the World Health Organization defined health not as the absence of illness but as the presence of physical, mental, and social well-being. 1 However, it was not until the 1980’s that the primary focus of research and policy efforts related to aging shifted from disease and decline to health and growth. The term successful aging was made popular in the late 1980s with the seminal work from the MacArthur study, in which successful aging was defined as involving 3 main factors (1) being free of disability or disease, (2) having high cognitive and physical abilities, and (3) interacting with others in meaningful ways. 2 Since then, numerous definitions and models of successful aging have been introduced with some estimating only 1% of the population achieve successful aging, whereas others estimate closer to 90% of people experience it.3,4 When asked, older individuals typically describe successful aging as being productive, mentally sharp, and able to do what is important to them for as long as they can.
Given the substantial increase in the 65-and-older population, which grew by over one-third since 2010, it is important to understand how we can help the aging population continue to live a meaningful life. Maintaining cognitive function is an important component to determining successful aging. Brain health has a significant impact on activities of daily living and the ability to live independently, as well as contributes to our physical health. 5
In light of its critical role, we have seen an increased attention to brain health from medical and scientific communities, as well as businesses over the last decade. The global neuroscience market was estimated at US$42.5 billion in 2022 and is expected to grow at a compound annual growth rate of 5.56% from 2023 to 2030. 6 In 2013, the U.S. announced the launch of the Brain Project, which aims to accelerate the development and application of new technologies to reveal the dynamic changes of the brain structure and function with aging. Shortly after, US$177 million was donated to establish the Global Brain Health Institute, which is the largest program grant ever made by the Atlantic Philanthropies. The Global Brain Health Institute is dedicated to protecting the world’s aging populations from threats to brain health through training, research, dissemination of knowledge, and advocacy. 7
Research has increased our understanding of prevention and intervention mechanisms to promote a healthy brain. Today we know that the aging brain retains a considerable functional plasticity, and that this plasticity is positively promoted by genes activated by different lifestyle factors. 8 Research suggests that lifestyle behavior carries more influence on brain health than genetics. In fact, several of the key modifiable risk factors linked to cardiovascular disease are also closely associated with brain health. The American Heart Association (AHA)/American Stroke Association Presidential Advisory identified 7 metrics to define optimal brain health in adults that originated from AHA’s Life’s Simple 7. Specifically, they recommended not smoking, physical activity, a healthy diet, a normal body mass index (<25 kg/m2), age-appropriate blood pressure (<120/<80 mm Hg), total cholesterol (<200 mg/dL), and fasting blood glucose (<100 mg/dL). 9 This aligns with a 2019 systematic review showing obesity, type 2 diabetes, hypertension, and smoking were each associated with a 41%–78% increased risk of dementia. 10
How Does Lifestyle Play a Role?
Our lifestyle choices can change both how our genes are expressed and how our brain functions. Additionally, lifestyle behaviors such as physical activity, a healthy diet, not smoking or smoking cessation, prioritizing sleep, social engagement, etc. can impact the development of other risk factors of cardiovascular disease and cognitive decline.11,12 Let’s look at hypertension and diabetes, both diseases that can be influenced by lifestyle. Hypertension is known to accelerate the process of atherosclerosis. If arteries to the neck and brain are impacted, blood flow can slow, decreasing the supply of oxygen and nutrients to parts of the brain, as well as decreasing the removal of waste products. Further, high blood pressure has been shown to damage the tiny blood vessels in the parts of your brain responsible for cognition and memory. These negative effects on the brain have been linked to high blood pressure even in middle-aged adults.13,14 Therefore, blood pressure control is needed through prevention and better treatment of hypertension to reduce the risk of neurodegenerative diseases.
The presence of type 2 diabetes also predicts cognitive decline 15 and dementia. A meta-analysis of 28 observational studies showed that diabetes increased the risk of all types of dementia by 73%, vascular dementia by 127%, and Alzheimer’s disease by 56%. 16 The duration of type 2 diabetes is related to the degree of brain shrinkage, 17 which is associated with cognitive decline. In fact, in 2021 research looked at over 10 000 individuals over a 32-year follow-up and found that those who had been living with diabetes for more than 10 years had 2 times the risk of dementia compared to those without diabetes. Additionally, there was a 24% increased risk of dementia in those over the age of 70 with every 5-year increase in diabetes diagnosis. 18
Protective Behaviors
In this issue, Whitsel and colleagues discuss the significant role physical activity plays in promoting brain health– through promotion of neuroplasticity and neurogenesis–and reducing the risk of neurodegenerative diseases. 19
In addition to physical activity, smoking has been identified as the third most important modifiable risk factor for dementia. The oxidative stress caused by smoking that leads to vascular, inflammatory, and neurodegenerative processes are thought to influence the link between smoking and poor brain health. 20 However, a recent review by Zhong et al suggests that smoking cessation decreases risk for Alzheimer’s, Vascular dementia, or all-cause dementia similar to non-smokers. 21
A healthy diet has been shown to improve cognitive function in middle aged and older adults, partly due to its positive impact on reducing the risk of chronic diseases, such as cardiovascular disease, hypertension, type 2 diabetes. Evidence also suggests consuming a diet high in sugar and refined grains increases neuronal damage and dementia risk, even in the absence of chronic disease. 22 Results from numerous observational studies support that following cardio-protective diets, such as the Mediterranean or DASH (Dietary Approach to Stop Hypertension) diets that emphasize high consumption of fruits and vegetables, is also associated with slower cognitive decline with aging 23 and reductions in mental health disorders. 24 Specifically, research has shown that higher adherence to the Mediterranean Diet is associated with less brain atrophy, 25 whereas lower adherence to the Mediterranean Diet was associated with greater 3-year reduction in total brain volume. 26 These results may have something to do with the benefits of extra-virgin olive oil, a staple in the Mediterranean Diet. Millman et al showed that diets high in extra virgin olive oil were related to less dementia risk. 27 Further, moderate evidence exists on the benefits caffeine has on brain health. In a systematic review, 100 to 400 mg of caffeine/day was associated with less dementia and cognitive decline. 28
In terms of diet, excessive alcohol intake and alcohol dependence are major risk factors for dementia, particularly with prolonged use. Historically, it has been hypothesized that light to moderate alcohol intake (defined as no more than 1 drink a day for women and 2 for men) is protective against cognitive decline. An analysis from the Health and Retirement Study Cohort showed that low to moderate alcohol drinking was associated with better global cognition scores, although there were racial/ethnic differences observed. 29 That being said, other research has found that even moderate alcohol intake is linked to pathological changes in the brain. Results from the Whitehall study showed a dose-response relationship between amount of alcohol consumed and brain shrinkage. Individuals who consumed 4 or more drinks a day were 6 times more likely to experience hippocampal shrinkage as nondrinkers, while moderate drinkers had 3 times the risk. However, cognitive function was only negatively impacted in heavy drinkers. 30 As a result of these contradictory results, more research is needed in this area to determine the impact of low to moderate alcohol consumption on brain health.
Social engagement and belongingness also protect our brains, whereas social isolation and loneliness are risk factors for cognitive decline and dementia. The Betula study asked over 1900 participants, “Do you feel lonely?” and then followed them for an average of 20 years to assess outcomes. Those who expressed feeling lonely had a 51% increased risk of all-cause dementia compared to participants who did not feel lonely. 31 Researchers are still trying to understand this association but believe it may be linked to the relationship between loneliness and depression, and/or the effects of loneliness on the cardiovascular system.
Further, with social engagement comes social support, which enhances our sense of purpose. Having a clear sense of purpose in life is associated with reduced pathological brain changes associated with all-cause dementia and Alzheimer’s disease.32,33 In this issue, authors Patty Purpur DeVries, Jack Groppel, and Diana Thomas discuss neuro-literacy as a process that helps us learn to know ourselves and to better understand and align our lives with our sense of purpose. A higher sense of purpose in life is strongly associated with lower levels of depression, another risk factor of cognitive decline and dementia. 34 Depression has been linked to changes in both brain structure and function, as it can result in the loss of brain cells in several brain regions, including the hippocampus, which is involved in memory and learning.35,36
While these protective factors have all been shown to be favorable to brain health, it is important to consider social determinants of health to fully understand how likely one is to engage in these behaviors. Poor socioeconomic status is strongly linked to unhealthy behavioral environments, including smoking, poor nutrition, and substance use disorders. 37 Physical activity participation is largely influenced by social circumstances including access, availability, affordability, safety, and social norms of physical activity. Data from the Leipzig Research Centre for Civilization Diseases (LIFE) Adult Study showed that all social determinants (living situation, social isolation, education, net equivalence income, occupational status, social economic status, and employment) with the exception of marital status were significantly associated with lifestyle behaviors that promote brain health. Therefore, taking a social-ecological approach to health may maximize risk reduction. 38
The Workplaces Role in Brain Health
Results from a recent 2022 survey show that 8 out of ten Americans believe their work life plays a major role in their brain health. The survey results also revealed that nearly half of Americans are feeling burned-out (43%), and over 70% report feeling unappreciated and unsatisfied. 39 These findings indicate a common lack of brain health promotion in the workplace. However, there has been an increased attention on brain health in the workplace over the last few years, as research is pointing to the role brain health plays on job performance and engagement.
In this issue, Kelly O’Brien underscores how workplaces can and should leverage valuable insights from neuroscience when developing policies, programs, and their built environment to foster a healthier and more productive work environment. This aligns with research from the Center for Brain Health at the University of Texas at Dallas that suggests workplace design is a key factor in whether the workplace acts as a protective or risk factor to one’s brain health. In 2021, the Center for Brain Health at the University of Texas at Dallas partnered with HKS Inc. to conduct a longitudinal study to assess the impact of workspace design on brain health. Findings show that offering workers access to a range of physical and digital spaces that meet their various needs better supports their brain health. 40 For example, offering focused spaces that allow for deep concentration with little to no interruption, as well as collaboration environments, such as shared spaces or the available technology that allows easy connection to co-workers can reduce stress and boost cognitive functioning. Data support this investment, as job stress is estimated to cost American companies more than US$300 billion a year in health costs, absenteeism and poor performance. Further, 40% of job turnover, a large business expense, is due to stress.41,42
A group of industry experts have worked to develop an Organizational Brain Health Best Practice Score using existing practices listed in the HERO Health and Well-being Best Practices Scorecard in Collaboration with Mercer© (HERO Scorecard). 43 The goal of this Brain Health score is to help organizations assess their workforce brain health initiatives and set goals for improvement. The score includes practices related to policies, programs, and the built environment that research shows are related to improved brain health. Therefore, this score includes HERO Scorecard items related to lifestyle behaviors, social well-being, and built environments that reduce stress as outlined above. Research will be done to link this organizational score to business outcomes (productivity, engagement, retention, etc.) to further understand the impact brain health plays in our workforce. So stay tuned!
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.