A large study provides 10-year absolute estimates for dementia risk. The scientists hope that by identifying people at high risk, specialists might be able to put in place early strategies for prevention.

According to the World Health Organization (WHO), every 3 seconds a new case of dementia is diagnosed.

It is characterized by cognitive impairment, such as having trouble recalling memories, solving problems, and reasoning logically.

Some of the main dementia risk factors include aging, stroke, and high blood pressure.

Recent studies have also found that biological sex and a particular variation in the APOE gene—the e4 allele—both affect a person's overall risk.

The APOE gene encodes apolipoprotein E, a protein that plays a vital role in regulating cholesterol levels, and which may also be key in reducing the levels of the protein beta-amyloid, which can form toxic plaques in the brain.

A team at the Copenhagen University Hospital in Denmark believes that if we can identify people at the highest risk for dementia early on and understand what places them at such a high risk, we may also be able to implement appropriate preventive measures.

The researchers conducted a large population study in order to calculate the 10-year absolute risk estimates for dementia based on age, sex, and the existence of the e4 allele of the APOE gene.

Study coauthor Professor Ruth Frikke-Schmidt and colleagues published their results in the Canadian Medical Association Journal.

The three factors that determine high risk

The researchers analyzed the medical data of 104,537 people from Copenhagen in Denmark. They obtained this information through the Copenhagen General Population Study (conducted in 2003–2014) and the Copenhagen City Heart Study (1991–1994 and 2001–2003).

"Recently," explains Professor Frikke-Schmidt, "it was estimated that one-third of dementia [cases] most likely can be prevented. According to the Lancet Commission, early intervention for hypertension, smoking, diabetes, obesity, depression, and hearing loss may slow or prevent disease development."

"If those individuals at highest risk can be identified," she goes on, "a targeted prevention with risk-factor reduction can be initiated early before disease has developed, thus delaying onset of dementia or preventing it."

Following their analysis, Professor Frikke-Schmidt and her colleagues revealed that a combination of three factors—biological sex, advancing age, and the APOE gene variation—appear to mark groups that are at high risk of developing dementia.

In terms of age and sex, the scientists determined a 7% risk for women in their 60s and a 6% risk for men at the same age, while women in their 70s have a 16% risk and men experience a 12% risk at that point.

When people reach age 80 or older, risk increases even more for both women and men, arriving at 24% and 19%, respectively.

In their paper, the researchers conclude that:

"The present absolute 10-year risk estimates of dementia by age, sex, and common variation in the APOE gene have the potential to identify high-risk individuals for early targeted preventive interventions."

However, they also warn that the estimates provided in the recent study are only for individuals of white European descent and therefore may not apply to other populations.