Dementia, Alzheimer's not an inevitable part of aging: Study

Dementia and Alzheimer's disease may not be an inevitable part of aging, according to a recent Dutch study, which identified 100-year-olds with high cognitive performance despite risk factors for decline.

This six-year study of centenarians -- people who are over 100 years old -- found that despite high levels of a brain marker associated with cognitive decline, called amyloid beta, these centenarians were still sharp and performed well on cognitive tests. The researchers concluded these elderly subjects may have resilience mechanisms protecting them from memory loss.

In fact, they said the risk of dementia may not necessarily increase once you pass your 100th birthday.

"A person between 70 and 95 years old is exposed to the same dementia risk as a person who lives between age 100 and 102," said Henne Holstege, Ph.D., of Amsterdam University Medical College in the Netherlands, who was involved in the study.

These results provide a hopeful glimmer to some that although dementia and Alzheimer's is more likely to occur with an increase in age, it won't be everyone's fate.

"Age is the No. 1 risk factor for Alzheimer's, but these findings show us that it's possible for centenarians to thrive despite their advanced age," said Dr. Richard Isaacson, director of the Alzheimer's Prevention Clinic at Weill Cornell Medicine and New York-Presbyterian Hospital, who headed the study.

Although these findings shed light on aging and cognitive function, it still remains a complex phenomenon that needs more exploration, according to some experts.

"Dementia and Alzheimer's tend to be multifactorial conditions, meaning that a mix of genetics, age, environment, lifestyle behaviors and medical conditions that coexist together and can lead a person toward or away from cognitive decline," said Isaacson.

Researchers still aren't sure exactly why some people are protected from cognitive decline, while others are spared. The researchers in the study proposed some of these protective factors associated with cognitive performance could be education, frequent cognitive activity and even IQ. But there can be more at play.

"There could be protective immunologic and cardiovascular risk factors that help keep their brains resilient and cognitively functional even in old age," said Dr. Gayatri Devi, a neurologist and psychiatrist at Lenox Hill Hospital in New York City.

The role the brain markers analyzed in the study play on memory, including a sticky plaque called amyloid beta typically found in the brains of people with Alzheimer's, is now hotly debated among experts. The varying presence of these markers in this study further contribute to this complicated process.

"It's important to understand that the presence of amyloid in the brain does not definitively mean a person will develop dementia," said Isaacson. "There are other factors and lifestyle behaviors that can make us resilient and resistant to cognitive decline."

Importantly, there are some caveats to this study. For instance, the brain markers were only analyzed in 44 of the participants, so the findings may not apply to everyone, and more research needs to be done to learn about the complexity of aging.

Other studies have investigated prevention of cognitive decline. According to the 2020 Lancet Commission Report, 40% of dementia cases may be preventable based on modifiable risk factors. Some of these previous studies have had success in improving cognitive function and reducing risk.

A study by Isaacson's team at the Alzheimer's Prevention Clinic found it was possible to improve cognitive function and reduce risk, especially in those who followed suggestions on lifestyle modification, such as exercise, nutrition, vascular risk and medications.

Even though more is being discovered and debated, experts still recommend maintaining a healthy lifestyle, including balanced eating, exercising and doctor visits, to maintain cognition during aging.

"It's essential for people at risk to see their doctors on a regular basis and consider cognitive screening tests," said Isaacson.

Alexis E. Carrington, M.D., is a dermatology research fellow at the University of California, Davis and a contributor to the ABC News Medical Unit.