Chair exercise class at the Louis and Anne Green Memory and Wellness Center at Florida Atlantic University, Boca Raton. Photo courtesy of the Louis and Anne Green Memory and Wellness Center.

Dementia has long been a diagnosis dreaded by patients and families, as there is no cure. Despite decades of effort, scientists have had little success in developing effective treatments or methods to prevent or slow down the characteristic brain deterioration.

Nearly 6 million people in the United States, including about 14% of the population ages 71 years and older, are afflicted. Dementias, including Alzheimer disease, are among the most common causes of disability and dependency in older adults and projections of the actual number of Americans with dementia—as much as 13.8 million by 2060—suggest rapid growth as the population ages.

Some progress, however, has been made in understanding symptoms and progression of dementias. Recent studies have also shed light on potentially modifiable risk factors, identified new methods of diagnosis, and explored ways to slow disease progression and improve patients’ quality of life. Among these emerging insights are the possible influence of air pollution as a causal factor and the importance of social relationships in mitigating symptoms and reducing mortality.

Mitigation.

Researchers at the University of Adelaide in Australia compared dementia mortality rates in people over age 60 from more than 180 countries with each country’s data on household size, gross domestic product, urbanization, and aging. They found a strong positive correlation between large household size and reduced dementia mortality, independent of the other three factors. Lead investigator Wenpeng You told Neuroscience News, “[Our findings show] that human factors—relationships, a sense of connection and purpose, encouragement and praise, meaningful engagement with others—are all quite important in combating the progress of dementia.”

Causal factors.

In investigating possible environmental influences, several new studies indict air pollution as contributing to both higher incidence and greater severity of dementia. In a comparison of air pollution data with Medicare data from more than 24 million urban and nonurban U.S. residents, researchers from the Rollins School of Public Health at Emory University in Atlanta found that long-term exposure to both particulate matter and nitrogen dioxide was associated with increased incidence of dementia and Alzheimer disease. A separate 2022 study linked improvements in air quality to slower cognitive declines in older women, strengthening the case for continued pollution regulatory efforts.

Diagnostic testing.

Diagnosis of Alzheimer disease has long relied on expensive brain imaging scans or studies of cerebrospinal fluid combined with observational tests of cognitive function. Today, blood tests may be able to pinpoint people at higher risk for developing dementia, allowing for earlier intervention. In the Harvard Aging Brain Study, higher blood levels of a fragment of tau protein were associated with an increased risk of cognitive decline and Alzheimer disease. In the AHEAD trial (www.aheadstudy.org), coordinated by Brigham and Women’s Hospital in Boston, researchers at 75 centers across North America are looking at whether the PrecivityAD blood test for the amyloid-β biomarker can identify individuals at high risk for future cognitive changes.

Drug therapy.

Several experimental drugs are in the pipeline for approval by the Food and Drug Administration (FDA), but it’s too soon to celebrate success on the treatment front. In June 2021, the FDA fast-tracked approval of aducanumab (Aduhelm), a $28,000/year drug for IV administration. As the first new drug for Alzheimer disease since 2003, it generated tremendous excitement despite caution from experts about inadequate evidence of efficacy as well as serious side effects, including brain bleeds. Clinical trials only measured reduction of amyloid-β plaque in the brain as a surrogate end point; they did not document actual clinical benefit.

The FDA’s own Peripheral and Central Nervous System Drugs Advisory Committee opposed approval, calling for additional testing. Critics also noted inadequate representation of people from historically excluded racial and ethnic groups. For example, only 0.6% of clinical trial participants identified as Black, even though older Black adults experience Alzheimer disease at rates up to double those of older White adults.

In response to the criticism, the Centers for Medicare and Medicaid Services decided to pay for aducanumab treatment only for patients enrolled in clinical trials. Among the drug’s adverse effects are brain edema and/or hemorrhage (occurring in 40% of trial participants), hypersensitivity reactions, and altered mental status.

Care innovations.

In addition to insights about the value of relationships to slow progression of dementia symptoms, a body of knowledge is emerging on how to interpret the cause of certain patient behaviors. According to Natalie Baker, president of the Gerontological Advanced Practice Nurses Association, “inappropriate behaviors” in people with dementia “are the result of unmet needs.” The person might be hungry, thirsty, constipated, bored, or in pain, and therefore should not simply be labeled as uncooperative or disruptive without consideration of the cause.

Baker offered an array of tasks for cognitively impaired persons to mitigate disruptive behavior such as folding laundry, playing “their” music, dancing, kitchen duties, and gardening. She added that in institutional settings, such individualized care quality requires investment in well-trained RNs, LPNs, and certified nursing assistants and low nurse-to-resident ratios.

Sources: You W, Henneberg M. PLoS One 2022;17(3):e0263309; Shi L, et al. Nat Commun 2021;12(1):6754; Younan D, et al. PLoS Med 2022;19(2):e1003893; Chhatwal JP, et al. Nat Commun 2020;11(1):6024; Manly JJ, Glymour MM. JAMA Neurol 2021;78(11):1305-6.

(Editor’s note: You can find a version of this article and other news stories in our June issue, including articles on maternal morbidity and mortality during COVID-19 and the breast cancer screening debate. And for more on Azheimer’s disease and related dementias, see the June editorial, which provides a personal perspective on these devastating diseases, and On the Cover, which highlights a nurse-led center is a state-designated memory disorder clinic that supports the needs of individuals with Alzheimer disease and other related dementias and their family caregivers.)