Want to Lower Your Risk of Dementia? You Don't Need a Blood Test

Scientists have created blood tests that may one day predict Alzheimer's disease before a person shows any signs of memory loss. But doctors say these tests are not ready for healthy people yet. The good news is that you don't need a test to start protecting your brain. Making healthy choices — especially in middle age — can help keep your mind sharp for years longer.

Alzheimer's disease is the most common form of dementia, a condition that affects memory and thinking. Right now, the U.S. Food and Drug Administration has approved four blood tests to help doctors find out if Alzheimer's is causing someone's memory problems. These tests can help people with early Alzheimer's get medicine that may slow the disease down a little. But they are only meant for people who already have symptoms, not for healthy people who are just worried.

Some people without any symptoms have tried to get these blood tests anyway. Doctors say that is not a good idea right now. Testing expert Nicholas Ashton, from Arizona's Banner Health, said that 'the worried well should not be getting those tests' unless they are part of a research study. He explained that the tests are not approved or recommended for people who feel fine.

So what should healthy people do instead? Experts say the best thing is to focus on habits that protect the brain. One big study found that people who reached middle age without high blood pressure, diabetes, or smoking stayed dementia-free for nearly 13 years longer than people who had all three of those health problems. That is a huge difference, and it shows that healthy choices really matter.

Dr. Josef Coresh of NYU Langone Health led that study. His team looked at health records from more than 12,000 people who were followed for many years, starting when they were around 56 years old. He found that high blood pressure, Type 2 diabetes, and smoking can hurt the blood vessels that feed the brain. Even avoiding just one or two of those problems helped people live with better brain health.

Here is how the blood tests work, and what their limits are. Alzheimer's leaves two unusual proteins in the brain — beta-amyloid, which builds into sticky plaque, and tau, which forms tangles that kill brain cells. Blood tests that measure a type of tau called p-tau217 seem good at detecting amyloid in people who already have symptoms. But a positive result is not a guarantee someone will get Alzheimer's, and sometimes the test is wrong.

One man named Mark Yost, age 60, from Phoenix, joined a Banner Health blood test study even though he has no symptoms. His result came back as 'intermediate,' meaning he might have some amyloid but not a worrying amount. Yost said the uncertainty was 'a little disappointing,' but he is staying active and working on a genealogy hobby to keep his brain busy. He plans to keep watching his results as he gets older.

Experts say everyone should follow brain-healthy habits, with or without a test. A major study last year found that healthier habits slowed mental decline in older adults at risk for dementia. The steps included 30 minutes of moderate exercise four times a week, strength training twice a week, and following the MIND diet, which stresses leafy greens, berries, whole grains, fish, and poultry. Doctors also recommend good sleep, staying socially connected, and keeping your brain active.

Middle age is a key time to make these changes, doctors say. Treating high blood pressure early and keeping it low is especially important for brain health. Even people who carry the APOE4 gene — which raises the risk of Alzheimer's — still benefited from healthier habits during middle age. 'Be very serious with your physician about the value of lowering it as early as possible for as many years as possible,' Dr. Coresh said.

As for the Alzheimer's blood tests, scientists are still working on them. Clinical trials are underway to see if drugs that treat Alzheimer's might also help people before they develop symptoms. Those results could change the advice about who should get tested. For now, the best medicine may simply be the healthy choices you make every day.