Could the Alzheimer’s riddle be solved in Cambridge?

Biogen Inc. has emerged as a front-runner in the global race to make the first drug to treat the memory-ravaging neurodegenerative disease. Already a public health challenge afflicting millions of Americans, Alzheimer’s diagnoses are expected to jump, and costs are projected to reach tens of trillions of dollars in the coming decades.

Clinical findings released in December confirmed that Biogen’s experimental drug aducanumab was reducing the amyloid plaque buildup around neurons that many scientists have pegged as an Alzheimer’s trigger. Drug candidates from Eli Lilly & Co. and other rivals have faltered. “To my knowledge, it was the first time anyone has been able to remove amyloid plaque in humans in a substantial way,” says Biogen chief medical officer Alfred Sandrock. “We think we’re seeing a slowing of disease progression.”


But the company is still a long way from developing a cure for Alzheimer’s, and it is hedging its bets. Biogen researchers are exploring at least two other approaches, including one that targets neurofibrillary tangles made up of tau protein deposits in the brain. And they’re seeking to understand the connection between amyloid and tau in the development of Alzheimer’s.

“That’s the $50,000 question,” says Michael Ehlers, Biogen’s executive vice president for research and development. “For society, it could be the $50 trillion question.”

Robert Weisman is a Globe staff writer. Send comments to magazine@globe.com. Follow us on Twitter @BostonGlobeMag.