One of society’s greatest achievements has been growing global life expectancies. Over the last 100 years, the average global life expectancy has more than doubled, with a 25-year gain in longevity in the United States. Our global longevity is a triumph of public health and medical advances.
But longevity also has caused concerns. Increasing age is the single greatest non-modifiable risk factor for dementia. Dementia incidence is set to skyrocket as our population ages, rising from about 6 million people in the United States in 2020 living with dementia to 14 million in 2050.
The World Health Organization estimates that 55 million people have dementia across the globe, with more than 60 percent of those people living in low- and middle-income countries. “As the proportion of older people in the population is increasing in nearly every country, this number is expected to rise to 78 million in 2030 and 139 million in 2050.” While the prevalence, attendant challenges and costs of caring for loved ones with dementia are going up, the number of potential caregivers and resources available to help are declining due to lower birth rates. If, as some say, demography is destiny, then it would appear we are heading for a brain health crisis.
Almost 100 percent of adults said that maintaining and improving brain health was critical, but only about half were doing what is required.
In a 2015 nationally representative survey of adults ages 40 and older, 98 percent of adults said that maintaining and improving brain health was important, but only about half were participating in activities known to protect cognitive health.
People reported they rarely engaged in sustained brain-healthy behaviors, the biggest barrier being not knowing what would actually benefit their brain. Consequently, AARP launched the Global Council on Brain Health (GCBH) to identify whether there were modifiable lifestyle factors that might reduce risks of cognitive decline and dementia as adults aged.
Cognitive Decline Not Inevitable
Six years later, we can confidently say cognitive decline is not inevitable as we age and that we can reduce risks to brain health through modifiable lifestyle interventions. Even though our 2021 AARP brain health survey found that 6 out of 10 adults older than age 40 in the United States believe cognitive decline inevitably occurs with aging, the vast majority of adults will never experience cognitive decline significant enough to interfere with their lives.
According to a review by the American Academy of Neurology (AAN), the prevalence of mild cognitive impairment (MCI) by age is:
- 6.7 percent—ages 60 to 64
- 8.4 percent—ages 65 to 69
- 10.1 percent—ages 70 to 74
- 14.8 percent—ages 75 to 79
- 25.2 percent—ages 80 to 84.
Dementia incidence was 14.9 percent in individuals with MCI who were older than age 65. Of course, all of us want to be in the majority of adults who reach a very old age without significant cognitive impairment or dementia. What makes those people so cognitively resilient? Some who even have accumulations of amyloid in their brains, one of the proteins thought to be responsible for Alzheimer’s Disease, the most common form of dementia.
Social Determinants Play a Large Role
In the past 10 years, neuroscience has made giant leaps forward in understanding what can help people build cognitive resilience. During that same period, we have come to better understand that the social determinants of health control the likelihood of healthy aging and maintaining brain health as much—if not more so—than do genetics.
The science demonstrates that there are modifiable lifestyle factors (quitting smoking, correcting hearing loss, maintaining low blood pressure, exercising, maintaining a healthy weight, getting enough sleep, remaining engaged, managing blood sugar) that can reduce risks for cognitive decline at the population level by up to 40 percent, and there are strategies to help people reduce risks to their brain health at any age.
The GCBH has now issued 10 reports on modifiable lifestyle factors providing scores of recommendations and practical tips on how to reduce risks to brain health as one ages. But maintaining brain health is not simply a matter of personal choice. The GCBH’s eleventh and latest report on COVID-19 vividly demonstrates how society influences personal health states.
These same social determinants of health are responsible for the health disparities in dementia rates we see in the United States.
The social determinants of health often can limit people’s ability to adopt and maintain healthy habits. The geographic, economic and cultural environments in which we live can make healthy lifestyle choices difficult to make or sometimes even impossible.
These same social determinants of health are responsible for the health disparities in dementia rates we see in the United States, where Black Americans have dementia at two times and Latino Americans have dementia at one and a half times the rate of White Americans.
We have been able to achieve declines in the rates of dementia for some groups of people in Europe and North America. We should seize opportunities to support policies such as expanded educational attainment, and reduction in cardiovascular disease burdens due to healthy eating, greater exercise and statin use that can reduce the incidence of cognitive decline and/or delay onset of dementia for all groups.
Delaying dementia onset by five years can cut the expected incidence rate in half. Knowing and sharing that cognitive decline is not an inevitable part of aging are first steps toward achieving healthier brains. We should use our collective power as ASA members to collaborate and champion these policies to prevent demography from becoming our destiny for dementia.
Sarah Lenz Lock is senior vice president of policy at AARP and executive director of the Global Council on Brain Health, in Washington, DC.