Microsoft cofounder Bill Gates joined the battle against Alzheimer’s disease on Monday, when he announced a $50 million investment in UK-based Dementia Discovery Fund (DDF), a venture capital fund. The investment is independent of his philanthropic work at the Bill & Melinda Gates Foundation. Gates will follow up his initial investment with an additional $50 million to be doled out to start-up ventures working on Alzheimer’s research, he told Reuters. 

Dementia is something personal to him. “My dad will celebrate his 92nd birthday in a couple weeks, a milestone that was practically unimaginable when he was born,” Gates, wrote in a post on his website, GatesNotes, on Monday. Gates did not say whether his father has dementia or not although he wrote that men in his family “have suffered from Alzheimer’s.” “Your risk of getting arthritis, Parkinson’s, or another non-infectious disease that diminishes your quality of life increases with each year. But of all the disorders that plague us late in life, one stands out as a particularly big threat to society: Alzheimer’s disease,” he added.

Although the number of studies investigating Alzheimer’s disease have grown in number over the past decade, scientists have not yet found a conclusive way to battle the disease, which is one of the top 10 causes of death in the U.S.. Every 66 seconds, someone in the United States develops Alzheimer’s, a rate expected to double by 2050, according to a 2016 study by the Alzheimer’s Association. For those who live into their mid-80s, there is a 50% chance of developing the disease, which causes decline in memory, language, problem-solving and other cognitive skills, the nonprofit says. “That trend will likely continue as baby boomers age, which means that more families will watch their loved ones suffer from cognitive decline and slowly disappear,” Gates wrote in his post.

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In addition to its emotional burden, the disease also results in significant economic costs for families, caregivers and healthcare systems. In 2011, 15.2 million Americans provided unpaid care for their loved ones valued at over $210 billion, an Alzheimer’s Association statement from 2013 concluded. The same statement said that Alzheimer’s expenditure will reach a total of $20 trillion over the next 40 years. Americans will spend $259 billion caring for those with Alzheimer’s and other forms of dementia just in 2017, according to the association.

The DDF, whose board includes the UK government as well as pharmaceutical giants like Biogen, GlaxoSmithKline, Johnson & Johnson, Eli Lilly, and Pfizer, has already invested in 12 ventures fighting Alzheimer’s in both the UK and the U.S. since it was founded in 2015. “We welcome Bill Gates’ involvement as we collaborate to solve one of the biggest issues in global healthcare,” Kate Bingham of healthcare venture capital firm SV Health, which manages DDF, said in a statement.

Along with his wife Melinda Gates and fellow billionaire Warren Buffett, Bill Gates started the Giving Pledge in 2010 and committed to giving away more than half of his net worth in his lifetime. In October, he was unseated by Amazon founder Jeff Bezos as the world’s richest person and will likely drop down the list in the near future, due to his philanthropic efforts.

“This is a frontier where we can dramatically improve human life,” the 62-year-old philanthropist said in a press release on Monday, “It’s a miracle that people are living so much longer, but longer life expectancies alone are not enough. People should be able to enjoy their later years – and we need a breakthrough in Alzheimer’s to fulfill that.” – Written by