(CNN) Besides a cure, what do those afraid of Alzheimer's disease need most? According to entrepreneur and philanthropist Bill Gates, a key need is a "reliable, affordable, and accessible" diagnostic test. To jump-start that research, Gates announced today that he has joined a coalition of philanthropists who are investing $30 million to create a venture fund called Diagnostics Accelerator.
"We need a better way of diagnosing Alzheimer's -- like a simple blood test or eye exam -- before we're able to slow the progression of the disease," Gates wrote in a statement announcing the investment. "Imagine a world where diagnosing Alzheimer's disease is as simple as getting your blood tested during your annual physical."
An accurate test is critical, Gates says, because science shows that Alzheimer's can begin more than a decade before the first outward signs of decline. Yet people today are cognitively tested only when symptoms have progressed to the point at which the disease is affecting daily life. By then, much of the damage is done.
The next steps are spinal taps or imaging tests such as PET scans to identify markers for changes in the brain. Both are extremely expensive, and most insurance plans in the US will not reimburse patients, Gates said.
"Spinal taps can be scary and uncomfortable, and PET scans require the patient to stay perfectly still for up to 40 minutes," Gates said. "That's difficult for anyone to do -- but especially someone with Alzheimer's."
Alzheimer's is a progressive mental deterioration of the brain that destroys memory and thinking skills until the person is unable to do even the simplest of tasks. Irreversible after it begins, it's thought to be caused by a buildup in the brain of beta amyloid plaques and neurofibrillary tangles called tau. The Alzheimer's Association says the disease is the sixth leading cause of death in the US, killing more than breast and prostate cancer combined. Estimates show nearly 6 million Americans are currently living with Alzheimer's; that number is projected to rise to nearly 14 million by the year 2050.
Identifying those with Alzheimer's is also critical to the success of clinical trials on potential medications or treatments. According to Gates, scientists are stymied in moving forward with research because "it's currently so difficult to find enough eligible patients for a clinical trial that it can take longer to enroll participants than to conduct the study."
Studies have shown one of the reasons for that shortage is the inability of primary care physicians to identify the signs of Alzheimer's in their elderly patients in the short time allocated to patient visits. Compounding that problem is the likelihood an elderly patient might already have diabetes, heart disease or other chronic illnesses that can mimic or cause those symptoms.
Gates hopes to solve those problems using a venture philanthropy fund to marry the best of cutting-edge research with the incentive of a money-making product for "real patients." If any of the ideas succeed, said Gates, "our share of the financial windfall goes right back into the fund."
In addition to Gates, the fund is supported by the Alzheimer's Drug Discovery Foundation, created by Estée Lauder billionaires Leonard and Ronald Lauder; the Charles and Helen Schwab Foundation; and the Dolby Family, among others.
Gates began another fund dedicated to Alzheimer's research, the Dementia Discovery Fund, in November. In an exclusive interview with CNN Chief Medical Correspondent Dr. Sanjay Gupta, Gates said he was investing $50 million of his own money partly because of his personal experience with Alzheimer's.
"Several of the men in my family have this disease," he told Gupta. "And so, you know, I've seen how tough it is. That's not my sole motivation, but it certainly drew me in.
"Anything where my mind would deteriorate" is, he said, one of his greatest fears. He's seen the hardship it has caused in his own family. "I hope I can live a long time without those limitations," he told Gupta.
The Dementia Discovery Fund is a private-public research partnership focused on some of the more novel ideas about what drives the brain disease, such as looking at a brain cell's immune system. It was the first time Gates made a commitment to a noncommunicable disease; prior work done through his foundation had mostly focused on infectious diseases such as HIV, malaria and polio.