Scientists are focusing on the APOE E44 gene and how much it raises the risk of developing dementia.

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People at high risk for dementia can be identified before they have any symptoms.

In fact, they can be diagnosed early enough to make lifestyle changes that could lower their odds of developing diseases like Alzheimer’s.

That’s the conclusions from researchers in a new study.

Danish researchers who studied decades’ worth of data on more than 100,000 people — including those with a genetic predisposition for dementia — say they were able to predict the 10-year risk of developing the disease.

Among those carrying the APOE E44 gene, the risk of dementia among women ages 60 to 69 was 10 percent. For men, it was 8 percent.

From ages 70 to 79, the risk rose to 22 percent for women and 19 percent for men. By age 80 or older, the risk rises to 38 percent and 33 percent, respectively, the researchers estimated.

For Alzheimer’s disease specifically, the risk was 7 percent for women and 6 percent for men ages 60 to 69. For ages 70 to 79, it was 16 percent for women and 12 percent for men. By age 80 and older, it was 24 percent for women and 19 percent for men.

“Age, sex and APOE genotype robustly identify high-risk groups for Alzheimer disease and all dementia,” researchers led by Dr. Ruth Frikke-Schmidt, a professor at the University of Copenhagen, concluded in the study published in the Canadian Medical Association Journal. “These groups can potentially be targeted for preventive interventions.”

“Despite important preventive efforts over the last decades — resulting in decreased smoking, lower blood pressure and lower cholesterol levels in the general population — physical inactivity, overweight, and diabetes remain threats for our health care system, and in particular for cardiovascular disease and dementia,” the researchers added. “Intensifying preventive efforts in general is thus of crucial importance, and especially for those patients at highest risk who most likely will benefit the most from early and targeted prevention.”

Frikke-Schmidt told Healthline that the findings could aid researchers who are testing preventative programs with specific high-risk groups, such as the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER).

“We still don’t know whether a targeted intervention would benefit high-risk groups the most,” she said. “While we wait for the results of such trials, there is sufficient evidence to say that what is good for the heart is good for the brain.”

Dr. David A. Merrill, a neurologist and geriatric psychiatrist at Providence Saint John’s Health Center in Santa Monica, California, told Healthline that taking preventative steps “may be more realistic than hoping or waiting for a cure” for dementia.

“While we have known that age is the greatest single non-modifiable risk factor for development of Alzheimer’s disease, we have not known until now how much risk age itself adds to the absolute risk of developing the disease,” he added. “Similarly, we now can confidently say that women are at higher risk than men for developing Alzheimer’s disease. Most importantly, this study offers support to the idea that clinical testing and discussion of the APOE genotype can add valuable information to care.”

Age 45 isn’t too early to get tested for risk of dementia, notes John Walker, PhD, co-founder of uMETHOD, which provides data-driven patient risk assessments to physicians.

“Because you have a known genetic risk doesn’t mean you’re going to get Alzheimer’s, but it does add to the sense of urgency about what you do to prevent it,” Walker told Healthline.

In fact, Walker argues that a risk assessment in childhood could help some people reduce their risk of getting dementia in their later years.

For example, he says that people with the APOE gene are known to be more susceptible to head trauma, another risk factor for dementia.

Walker added, “There are probably some sports you should not be playing” if you carry this gene.

Experts note that a major limitation of the study is that it looked at a mostly white, Nordic population in a limited geographic area.

“To me, the estimates seem a little low,” said Walker. “I think we in the U.S. are more obese than the people in Denmark — I think we’re in worse shape than them.”

The World Health Organization estimates that more than 50 million people worldwide have some form of dementia. Alzheimer’s is the most common form of the disease.