There is no cure for Alzheimer's, which destroys memory and other mental processes, and so Gates said he is investing his own money into the Dementia Discovery Fund, a private-public partnership to search for a solution.
"In the first example of its kind in dementia, the DDF has now brought together funding from the private sector, charity and industry, and we're especially pleased to get so much interest from the U.S. in a British fund", said Kate Bingham, Managing Partner of SV.
Humans have a almost 50 percent chance of developing Alzheimer's if they live into their 80s, and scientists have yet to find the cause of the disease, Gates wrote on his blog.
Asked how long he believes it will take to develop an effective treatment, Gates told Reuters: "It'll take probably 10 years before new theories are tried enough times to give them a high chance of success".
At least 5 million people in the USA are living with Alzheimer's and that number could grow to 16 million by 2050, according to the Alzheimer's Association.
DDF is backed by the government, charity Alzheimer's Research UK and several of the big pharmaceutical firms, including GSK, Pfizer and Johnson & Johnson, with the goal of finding an ambitious cure for dementia by 2025. He also plans to invest another $50 million in start-up ventures working in Alzheimer's research. That's, in part, because it's personal. This is something I know a lot about, because men in my family have suffered from Alzheimer's.
In a statement and video, the philanthropist highlights the urgency to make progress in our understanding of the causes of dementia, as numbers of people affected globally are on the rise.
"People should be able to enjoy their later years - and we need a breakthrough in Alzheimer's to fulfill that", Gates said.
Although Alzheimer's now has no cure, Gates expressed hope that the course of Alzheimer's can be substantially altered if progress is made in five key areas.
Alzheimer's is the most common type of dementia.
"My personal experience has exposed me to how hopeless it feels when you or a loved one gets the disease", he writes. "It's like a gradual death in terms of the person that you knew". This would make it easier for researchers to look for patterns and identify new pathways for treatment, he said.