THE risk of developing dementia could be much higher than previously thought, according to a study published Monday in the journal Natural medicine found.
Older studies estimated that about 14% of men and 23% of women will develop dementia during their lifetime. The new study puts that estimate higher, at around 42% for both men and women.
“I think this will be a very important study, and I think it will change the way we look at dementia,” said Dr. Ted Huey, director of the Memory and Aging Program at Butler Hospital in Rhode Island, who was not involved in the research.
More than anything, the increase in the risk and number of people with dementia – which researchers predict will double by 2060 — is the result of people living longer than previous generations, said Dr. Josef Coresh, study leader and director of the Optimal Aging Institute at NYU Grossman School of Medicine.
“Just the fact that the the population will age this means that the number of dementia cases will double overall,” Coresh said. Among Black Americans, for whom the risk is greater, the number of cases is expected to triple, he said.
About 10% of Americans over 65 have been diagnosed with dementia, according to the Centers for Disease Control and Prevention. Nearly 7 million people in the United States suffer from Alzheimer’s disease, the most common type of dementia.
The study involved more than 15,000 people in the United States who were followed for more than two decades. About a quarter of the participants were black and more than half were women – two groups known to be at high risk.
According to the study, the average lifetime risk of dementia at age 55 is 42%, but the risk is not the same at each age. The bulk of this occurred after a person’s 85th birthday. Between ages 55 and 75, the average risk of developing dementia was 4%, according to the study. By the time a person reached age 85, their risk was about 20%. The risk did not reach 42% until a person’s 95th birthday.
For Black Americans and women, the risk was higher, but the trend was similar.
Black Americans had a 7% risk at age 75, nearly double the average. At age 85 the risk increased to 28% and at age 95 it was 42%. For women, this risk was 3% at age 75, 21% at age 85, and 48% at age 95.
“We need to think about what causes this risk and how to prevent it,” Coresh said.
Previous research has shown that elevated risk may be caused by higher rates of diabetes and hypertension among Black Americans, largely due to inequalities in access to careand the structural racism that can cause stresswhich puts people at higher risk of dementia.
Much of the elevated risk seen in women can be attributed to the fact that, on average, women live longer than men – but that’s not all. A genetic variant called APOE-4, which increases the risk of developing Alzheimer’s disease, may further increase risk for women only for men of certain age groups. Research into whether pregnancy plays a role in dementia risk yields results mixed results.
Why is the risk of dementia higher than before?
Previous studies suggested that around 14% of men and 23% of women will develop dementia in their lifetime. The 42% risk found by these researchers is much higher, which can be explained by several factors, according to experts.
Previous studies, including Framingham Heart Study and the Rotterdam Studyboth published in the late 1990s, included a less diverse group of participants, all of whom lived in the same city. Experts say it’s a pervasive problem in dementia research.
Dr. Monica Parker, associate professor of neurology at Emory University’s Goizueta Alzheimer’s Disease Research Center, considers patients a primary care provider at the Good Samaritan Health Clinic in Atlanta. Many of his patients are immigrants and don’t speak English.
“Most of our academic health centers are not designed to accommodate non-English speaking people,” meaning that part of the population is often excluded from research, said Parker, who is also president of the American Foundation for Alzheimer’s disease. medical, scientific and memory screening advisory board and has served as a paid educational consultant for Eli Lilly, Biogen and Eisai, three companies that make Alzheimer’s disease drugs.
Other studies may have struggled to stay in touch with participants who developed dementia, Huey said.
The researchers in this study, however, “did a really good job of following people,” he said.
Finally, much available data on dementia targets only one type: Alzheimer’s disease.
“Saying dementia is like saying cancer. There are many subtypes,” said Michelle Mielke, professor and chair of epidemiology and prevention at Wake Forest University School of Medicine in North Carolina.
Alzheimer’s disease is the most common type of dementia, accounting for up to 80% of cases, according to CDC data. However, research that tracks only Alzheimer’s disease excludes dementia caused by other diseases such as cardiovascular and neurological diseases, Mielke said.
“All the diseases related to aging are increasing with this aging population, we’re seeing an increase in strokes, and that’s going to be a risk factor for vascular dementia,” she said. “Sometimes we are victims of our own success. People are living longer with many more comorbidities.
These comorbidities, including stroke, high blood pressure and type 2 diabetes, increase a person’s risk of dementia. It is also likely that more cases would have previously unknown are being diagnosed, said Dr. Peter Whitehouse, professor of neurology at Case Western Reserve University in Ohio.
In 2011, under the Affordable Care Act, Medicare started reimbursing providers for annual wellness visits including screening for cognitive decline.
“If more people go to a doctor’s office, they might do more testing and more cases will show up,” Whitehouse said.
Although the new data is striking compared to previous numbers, Dr. Andrea Bozoki, division chief of cognitive and behavioral neurology at the University of North Carolina School of Medicine, said people should remember that all the world will not develop dementia in old age.
“Less than half of people who reach 95 will have dementia,” she said. “Dementia is not an inevitable consequence of aging, no matter how old you are. »
Although some factors that increase the risk of dementia, such as genetics or exposure to air pollutioncan be beyond the person’s control, but the good news is that there are many ways to reduce the risk of dementia.
“Making sure that hypertension and diabetes are controlled will definitely help with cognition,” said Mielke, of Wake Forest University.
Get quality sleepwhich includes treating problems such as sleep apnea, can also reduce the risk of dementia, as can eat healthy. As a general rule, what is good for the heart is also good for the brain, and vice versa.
“We know that changes in vascular risk factors that help your heart also help your brain,” Coresh said.
