The number of people around the world with dementia is staggering and growing. The mind-robbing disease has no cure, but recent research is beginning to show how you may best be able lower your chances of getting it.

“It’s not yet definitive, but in the past 5 years, we’ve made progress on identifying modifiable risk factors for which the evidence is pretty strong,” says Kristine Yaffe, MD, professor of psychiatry, neurology and epidemiology at the University of California San Francisco and director of the Memory Disorders Clinic at the San Francisco Veterans Affairs Medical Center.

“Research from the past 2 to 3 years suggests that risk factors need to be focused on in midlife,” says Keith Fargo, PhD, director of scientific programs and outreach at the Alzheimer’s Association.

Consider high blood pressure. In a study published last August, researchers followed nearly 16,000 adults ages 44 to 66 for 24 years. They found that people with high blood pressure in midlife had a nearly 40% higher risk of dementia.

Millions more, but why?

It’s estimated that 82 million people worldwide will have dementia by 2030, according to the World Health Organization. Dementia causes a slow decline in thinking skills. It affects memory, mood, language, and other functions of the brain.

People with dementia eventually become unable to live independently and require around-the-clock care and attention.

Alzheimer’s is the leading cause, followed by stroke and other conditions that damage blood vessels can cause what’s known as vascular dementia. In addition to maintaining a healthy blood pressure, evidence has been building that keeping other heart health factors, such as cholesterol and diabetes in check, may lower your risk.

In a December study, for example, researchers reported that type 2 diabetes appears to cause brain changes that could harm memory and other brain functions. Another from earlier this month found that cholesterol seems to encourage the buildup of proteins in the brain that are believed to play a major role in the development of Alzheimer’s disease.

“Managing your blood pressure, your cholesterol, and, if you have it, your diabetes, will likely lower your risk of dementia later in life,” says Jagan Pillai, MD, PhD, a neurologist with the Cleveland Clinic Lou Ruvo Center for Brain Health.

Recent research also has pointed to other things that may contribute to brain health, including:

• Getting proper sleep

• Using hearing aids if necessary

• Safeguarding your head from injury

• Regular social interaction and other types of mental stimulation

The Link to Sleep

During sleep, the brain cleans house, flushing out toxic buildups of beta-amyloid, a protein that has been linked to Alzheimer’s disease. Poor sleep hampers the brain’s ability to perform this janitorial work.Over time, the buildup of toxins may lead to dementia.

A study published in March, which included 283 adults whose average age was 77, revealed a link between daytime sleepiness and higher amounts of beta-amyloid. And in a study published last July, researchers reported similar findings in 101 adults whose average age was 63.

“We don’t know exactly what explains the link between sleep and dementia, but it does seem that there is something about sleep and the clearing of beta-amyloid,” Yaffe says.

There likely are other explanations as well. For example, Pillai says uncontrolled sleep apnea may cause numerous small strokes that lead to memory and thinking problems later in life.

But recent research raises more questions than it answers. “A lot of the details are unclear regarding how sleep impacts Alzheimer’s disease and dementia in general,” Pillai says. And, says Yaffe, “We still don’t know whether treating your sleep problems would decrease your risk of dementia.”

Hearing and Social Stimulation

Last June, a major report on dementia added hearing loss to the list of significant modifiable risk factors.

Right now, though, experts don’t know what links hearing loss to dementia. The authors of the report suggest that hearing problems force the brain to work harder to understand what’s being said. Over time, that extra burden may cause harm. Or the dementia may come from social isolation.

If your poor hearing does not allow you to participate fully in conversations, you may lose the brain benefits that come from that type of mental stimulation.

Scharre agrees: “Most hearing loss occurs outside the brain and is not related to the brain, but if you’re not getting input or socialization, that may affect the brain indirectly.”

Protect Your Head

Head injuries also have been tied to dementia. In a study published in January, for example, researchers studied the health records of more than 164,000 people who’d had a traumatic brain injury (TBI).

Serious injuries doubled the risk of dementia, while repeated injuries nearly tripled it. Even after more than 30 years, the risk remained 25% higher than normal.

Recent research also suggests that even mild head injuries make dementia more likely. Yaffe and her colleagues studied veterans who had had mild concussions but did not lose consciousness.

In a study published earlier this month, she and her colleagues report that such injuries more than double the risk of dementia. More severe injuries boost the risk even higher.

Pillai points out that we can’t say if Yaffe’s results would apply to others besides veterans, but, he says, “it opens up a new area of concern.” The relationship between head injuries and dementia makes sense. As Scharre puts it, “Head injuries can’t possibly be helpful for the brain.” Nevertheless, the link is complicated and not well understood.

“Injury takes its toll, but we don’t know all of the mechanisms,” Yaffe says.

Not Just From Injuries

Genetics may play a role. One gene known to increase the risk of Alzheimer’s disease, ApoE4, may also contribute to a heightened risk of dementia following a traumatic brain injury, according to a study published in September. “I truly believe that there’s a huge impact from genetics,” Scharre says. “Certain genetics likely make you much more prone to the effects of concussion such that your brain is less able to heal or the inflammatory condition that arises maybe goes overboard and causes more damage.”

Eventually, tests might be able to identify individuals whose genes make it more dangerous for them to play football, where head injuries commonly happen. Scharre says that by that point we may also know how to modify those genes to reduce risk before the first hit occurs. In the meantime, though, avoiding injury is your best protection.

Minimizing Your Risks

Experts agree that to reduce your risk of dementia, focus on three targets: exercise, mental stimulation, and heart health. “There’s a very clear scientific consensus that physical exercise and activity lowers your risk of dementia later in life,” Pillai says.

Fargo says your goal should be to get sweaty a few times a week, but walking also may provide some benefits, if that’s all that you’re able to do. Scharre says mental stimulation can take many helpful forms, like solving crossword puzzles and playing strategic games like bridge, but he recommends activities that engage as many parts of your brain as possible.

One example: conversation, in which you listen, pick up on non-verbal cues like mood, all while considering what you’re going to say and then saying it. Finally, maintaining your heart health will help keep blood flowing to your brain, delivering needed oxygen and nutrients. Obesity, high blood pressure, high cholesterol, and other factors can make it harder for your heart to do its job.