Billions of dollars have been spent in pursuit of a pharmaceutical treatment for Alzheimer’s and other forms of dementia. Their fail rate through the 21st century is stuck at 100%.
The dominant story promoted by Alzheimer’s advocacy organizations, pharmaceutical companies, and academic experts has been that, without a cure, aging societies will face a demographic tidal wave of dementia—a “silver tsunami” unleashing devastating socioeconomic consequences.
Yet dementia rates have actually fallen in the United States, Canada, the United Kingdom, France, Sweden and the Netherlands over the past decade even though biotechnology continues to come up short. A 2020 study compiling data from those six countries from 1988 to 2015 calculated that, while the overall number of people affected by dementia is incrementally rising — as would be expected given the growing population of aging individuals — the incidence rate of dementia has consistently declined by 13% per decade and by 16% for Alzheimer’s, the most common form of dementia.
How can the dementia “tsunami” be losing momentum without effective drugs to prevent and treat the illness? And how can countries continue this somewhat paradoxical brain health trend?
We believe that looking at dementia through a population health lens provides some answers.
Older adults in the countries with decreasing dementia risk have cognitively benefited from two types of societal changes linked to overall public health improvements in the 20th century:
- Better prevention and treatment of cardiovascular disease
- Increased access to education
Healthier societies mean healthier hearts and heads
The human brain contains an intricate network of blood vessels, so its health is deeply intertwined with that of the heart and circulatory system. Nearly 20% of the heart’s output delivers oxygen and glucose to the brain. High blood pressure, high cholesterol, diabetes, obesity and associated metabolic syndrome, heart disease, sleep apnea, and other conditions can impair the heart and the extensive network of blood vessels in the vascular system, leading to heart attack, stroke, amputation, and more. When these conditions disrupt the flow of oxygen and nutrients to the brain, it can degrade the health and functioning of the organ and affect the mind.
Marked improvements in health care systems in high-income countries over the course of the 20th century have helped drive down the risk for cardiovascular disease, benefiting millions of aging brains.
These improvements don’t exist in a vacuum. They are the result of specific political and economic decisions that have improved population health.
Since the devastation of the two world wars and the Great Depression in between them, every country in which dementia rates are falling — excluding the United States — has legally obligated the state to extend health care coverage to all citizens. Elders in those countries have enjoyed lifespan access to clinical care, which has been instrumental in managing and preventing vascular illnesses.
Smoking cessation programs, like the Federal Cigarette Labeling and Advertising Act of 1966 and the Public Health Cigarette Smoking Act of 1969 in the U.S., have also been major contributors to better health. In the 1960s, 42% of U.S. adults smoked compared to only 14% in 2019. The success of these public health efforts in the U.S., Canada, and Western Europe has corresponded with decreased risk of the vascular diseases that can elevate dementia risk.
Lowering lead levels in the air and water has also been good for the heart and the brain. The U.S. was a global leader in this effort in the mid-20th century. Under the Clean Air Act, first enacted in 1963, lead was gradually phased out of gasoline sold in the country, reducing the environmental burden of this heavy metal — a known neurotoxin and risk factor for dementia — from vehicle exhaust and dropping collective lead levels in the blood of Americans by more than 80% between the 1970s and 1990s. In addition to damaging neurons and synapses at the molecular level, lowering IQ, creating emotional disturbances, and reducing academic achievement, lead exposure is also a major risk-factor for cardiovascular disease. Success reducing lead from the environment has benefited brains and vascular systems of countless citizens across the last 50 years.
Learning to reduce dementia risk
The other major societal pattern that has helped lower dementia rates — increased access to education — is also a population health success story.
One observation in nearly all of the multi-country studies showing reductions in dementia risk is a consistent rise in total years of education among older adults. In the U.S., for example, the percentage of adults ages 65 and older with a high school diploma increased from 40% in 1960 to 90% in 2020, and those with college degrees increased from 8% to nearly 37%. These cumulative years of education appear to now be conferring a strong protective effect on dementia risk for millions of people.
This finding is consistent with what is known as the cognitive reserve hypothesis — the notion that intellectual stimulation across the lifespan can, through mechanisms that aren’t yet fully-understood, render the brain more resilient to neuropathologies that accumulate with age.
In the U.S., rising education rates for current elders are directly linked to governmental interventions like the GI Bill, which provided subsidies for returning veterans to attend colleges and universities. More than 10 million World War II veterans took advantage of this opportunity, though this benefit was not equitably distributed, as Black veterans were barred from attending many public universities in the segregationist 1940s and 1950s. Veterans of subsequent wars continued benefiting from the GI Bill, while the Cold War intensified the expansion and subsidization of colleges. The introduction of Pell Grants in the 1970s expanded enrollment for students in financial need.
Thanks to these state interventions, between 1945 and 1975, the number of undergraduate students in U.S. colleges and universities increased five-fold and graduate students nine-fold.
A tangled road ahead
These positive brain health trends may soon begin reversing due to the reorganization of Western societies over the last several decades around radical free-market principles. This bipartisan shift, which is commonly referred to as neoliberalism or market fundamentalism, began in the 1970s in response to the crisis of stagflation and international oil shocks. It has transitioned the government’s role from capital control, redistribution, and public investment, as was generally the commitment of Western states during the post-Depression and post-World War II period in the mid-20th century, to facilitating global capital mobility, market expansion and deregulation, decreased taxation of the wealthy, deunionization, and cutting and privatizing public goods and services.
As Western states have gradually placed greater faith in the efficiency of markets while reducing public commitments to citizens, the societal conditions of the mid-20th century that had produced a robust middle class, improved public health, and ultimately engineered progress on dementia have deteriorated. Whereas cardiovascular disease declined in the post-war period, the U.S. is now experiencing a resurgence of chronic disease, with 6 in 10 Americans living with at least one chronic condition. Eighty million Americans are either uninsured or underinsured. And millions are coping, or trying to cope, with rising rates of depression, anxiety, and day-to-day financial worry in a deeply unequal, debt-burdened country characterized by declining population health, rising deaths of despair (from suicide, overdose, and alcoholism), and falling lifespans.
None of this bodes well for brain health.
Nor does the fact that trends toward increasing years of education are expected to level off for future aging Americans who have faced the barrier of soaring tuition costs in marketized higher education (underwritten by Wall Street) during a 40-year stretch of wage stagnation for the working class. And as has been tragically observed in cities like Flint, Michigan, and in Cleveland, Ohio, which we have both called home, the U.S. is dealing with a widespread lead crisis stemming from its aging water pipe infrastructure and the neoliberal austerity policies that have gutted regulatory oversight and cut spending on public goods and public health.
Alzheimer’s, a heterogeneous syndrome entangled with aging, is not likely curable via single-drug approaches. That will probably be the case for other age-related dementias as well. That’s why it is critical that we again reorder population-level structures, institutions, and social processes so they benefit the bodies and brains of future generations. A healthier society in which everyone is guaranteed nutritious food, safe drinking water, living-wage jobs, safe neighborhoods, quality health care, safe and affordable housing, higher education, and adult learning opportunities — in essence, a renewed 21st century commitment to broader prosperity, public health, and prevention — will be the best way to promote brain health and keep the dementia “tsunami” under control.
Daniel R. George is associate professor of Humanities and Public Health Sciences at Penn State College of Medicine. Peter J. Whitehouse is professor of Neurology at Case Western Reserve University. They are the authors of “American Dementia: Brain Health in an Unhealthy Society” (Johns Hopkins University Press, 2021).
https://www.statnews.com/2021/09/23/the-brain-health-paradox-dementia-rates-have-fallen-even-as-drugs-have-failed/
