U.S. dementia cases expected to surge with aging population

A new study finds that the risk of developing dementia at any time after age 55 among Americans is 42%, more than double the risk reported in older studies.

That risk of dementia translates into an estimated half a million cases this year, rising to 1 million new cases per year by 2060, according to the new work. Dementia involves a progressive decline in memory, concentration and judgment. The increasing number of cases is directly related to the aging of the US population. In addition to aging, a high risk of dementia is linked to genetic factors, as well as high blood pressure and diabetes, obesity, unhealthy diet, lack of exercise and poor mental health.

The study authors attribute the previous underestimates of dementia risk to unreliable documentation of the disease in medical records and on death certificates, minimal surveillance of early-stage dementia cases, and the underreporting of cases among racial minority groups, which are disproportionately be vulnerable.

This large study is a collaboration funded by the National Institutes of Health with NYU Langone Health and includes authors from Johns Hopkins University and other US institutions. The new study is based on information gathered from the ongoing Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS), which since 1987 has closely monitored the vascular health and cognitive function of nearly 16,000 participants as they age. ARIC-NCS is also the longest-followed cohort of African Americans in cognition and heart health, according to the researchers.

Publication in the magazine Naturopathy online on January 13, the study concludes that between 1987 and 2020, there were 3,252 study participants documented as having developed dementia. This translates to an overall risk of dementia among middle-aged Americans of 42%, which is an average of the 35% risk in men and the 48% risk in women. The additional risk in women was largely due to their lower mortality rates.

The new results also showed a higher risk in black adults and in those who carried a variant of the APOE4 gene (between 45% and 60%), which codes for a protein that transports cholesterol and other lipids in the bloodstream. It is thought that having a certain version of APOE4 is the biggest genetic risk factor for developing Alzheimer’s disease later in life.

“Our study results predict a dramatic increase in the burden of dementia in the United States in the coming decades, with one in two Americans expected to experience cognitive problems after age 55,” said senior investigator and epidemiologist Josef Coresh, MD , PhD, who serves as founding director of the Optimal Aging Institute at NYU Langone.

Coresh, the Terry and Mel Karmazin Professor in the Department of Population Health and professor in the Department of Medicine at NYU Grossman School of Medicine, says the projected increase in dementia cases is partly related to the fact that a progressive decline of brain function is often observed beginning in middle age, that women generally live longer on average than men, and that approximately 58 million Americans are now over the age of 65. One of the other key findings of the study was that the lifetime risk of dementia increases to more than 50% among those who reach age 75.

However, previous findings from this and other studies indicate that policies designed to prevent heart disease, such as blood pressure control and diabetes prevention, should also slow cognitive decline and prevent dementia.

The upcoming population growth in dementia cases poses a significant challenge for healthcare policy makers in particular, who should refocus their efforts on strategies to minimize the severity of dementia cases, as well as on plans to provide more healthcare services to people with dementia.”

Josef Coresh, MD, PhD, senior investigator and epidemiologist

Hearing loss in older adults has also been linked to an increased risk of dementia. However, only one-third of Americans with hearing loss use hearing aids. To address this, Coresh recommends more monitoring and testing, and possibly even government assistance programs to support healthy hearing among the elderly, including making hearing aids more widely available and affordable.

Coresh also argues that many more resources are needed to address racial disparities in health care, noting that while rates of dementia among white individuals are expected to double over the next forty years, rates among black individuals are expected to triple . Health policy should increase efforts in Black communities to improve education and nutrition for children, which he says previous research has shown is beneficial in preventing cognitive decline later in life.

For the latest analysis, researchers used data from the ARIC-NCS study and then modeled their lifetime risk projections using information from the US Census Bureau.

Funding support for the studies was provided by grants from the National Institutes of Health K24HL152440, K01DK138273, R01AG054787, 75N92022D00001, 75N92022D00002, 75N92022D00003, 75N92022D00004, 75N92022D00005, U01HL096812, U01HL096814, U01HL096899, U01HL096902 and U01HL096917.

In addition to Coresh, another NYU Langone researcher involved in this study is co-investigator Jordan Weiss, PhD.

Michael Fang, PhD, at Johns Hopkins University in Baltimore, Maryland, is the lead author of the study.

Other co-investigators and authors include Jiaqi Hu, MS; Marilyn Albert, PhD; A. Richey Sharrett, MD, DrPH; and Elizabeth Selvin, MPH, PhD, at Johns Hopkins; David Knopman, MD, at the Mayo Clinic in Rochester, Minnesota; B. Gwen Windham, MHS, MD, and Thomas Mosley, PhD, at the University of Mississippi at Oxford; Keenan Walker, PhD, at the National Institute on Aging in Baltimore; Rebecca Gottesman, MD, PhD, at the National Institute of Neurological Disorders and Stroke in Bethesda, Maryland; and Pamela Lutsey, PhD, MPH, at the University of Minnesota in Minneapolis.