There are a million reasons why our brains are important, so I’m glad that Bill Gates added $50 million to efforts to understand one of the ways the brain can be hobbled.

Gates is supporting efforts to understand and treat Alzheimer’s disease. His friend and Microsoft co-founder Paul Allen has already put money into brain research more broadly through the Allen Institute for Brain Sciences, which he founded in 2003. Allen has funded other research specifically targeted at Alzheimer’s, as well.

Seattle is also home to the Institute for Learning and Brain Science at the University of Washington, which focuses on brain development early in life.

People around here are interested in the brain at every stage of life.

Gates and Allen are both baby boomers, a group that has seen parents or other relatives transformed by Alzheimer’s and who fear the same thing might happen to them.

Alzheimer’s is scary and sad because it destroys a person’s memory and ability to think clearly. One in 10 Americans 65 or older have Alzheimer’s, which is the most common form of dementia. Half of people who live into their mid-80s will develop Alzheimer’s. It’s the sixth leading cause of death in the United States.

I worry about getting the disease because members of my family have been affected by it.

My mother is living with it, so I understand why Allen and Gates care so much about finding a way to prevent it, slow its progress or maybe some day cure the disease. She’s 93 now, but she was diagnosed with the disease when she was in her 80s.

It wasn’t obvious in the early stages that anything out of the ordinary was wrong. She had the kinds of memory lapses that are common for older people; no one noticed they were getting worse, though it’s clear looking back that she was changing.

She was a stellar cook, but she began occasionally putting the wrong ingredients in a dish, or letting a pot burn on the stove.

One evening she took a walk and stopped to knock on a neighbor’s door to ask if they could tell her where her house was. The neighbor told my younger brother, who lives a few blocks away.

We’ve been losing her ever since, a little bit each year. Now, she calls my two brothers Jerry. She asks if I’m calling from Long Beach, and I say, no that’s Bill. We have the same conversation every time we speak, and it repeats in a loop.

Allen’s mother died with the disease, and Gates wrote in a blog that he has seen it ravage men in his family.

In his blog last week, Gates wrote: “I know how awful it is to watch people you love struggle as the disease robs them of their mental capacity, and there is nothing you can do about it. It feels a lot like you’re experiencing a gradual death of the person that you knew. My family history isn’t the sole reason behind my interest in Alzheimer’s. But my personal experience has exposed me to how hopeless it feels when you or a loved one gets the disease.”

Gates made his gift to the Dementia Discovery Fund, a public-private partnership based in Britain. The money will help fund research that explores novel approaches to dealing with the disease. The British department of health is an anchor of the Fund, and for it, dementia is a priority, partly because the government funds health care. In the U.S., families are not so fortunate.

Alzheimer’s patients require constant, expensive care that puts a strain on health-care systems and on families.

There are no good options for most families who have to provide care for someone who has the disease. Everything about it is emotionally draining.

Gates believes we are at a point where a breakthrough is possible.

I hope he’s right.