For much of the 21st century, one theory has dominated research efforts to cure Alzheimer's disease: the amyloid hypothesis. Beta-amyloid is a protein that builds up in clumps, or plaques, in the brains of people with Alzheimer's disease and is linked to their cognitive decline.

But in recent years, despite the emergence of a couple of new drugs targeting these plaques, some scientists have begun to doubt the amyloid hypothesis. Donald Weaver, a professor of chemistry at the University of Toronto in Canada, is one of them.

Weaver no longer believes there will be one magic bullet found to cure Alzheimer’s disease. Instead, he advocates for a magic shotgun approach that is likely to involve multiple ways of treating the problem, including starting much earlier in a person’s life. He tells us about shifts in the understanding of Alzheimer's during his career of more than 30 years, and the theories now emerging about what might cause the disease and how to treat it.

This episode was written and produced by Katie Flood with assistance from Mend Mariwany. Gemma Ware is the host and executive producer. Sound design and mixing by Eloise Stevens and theme music by Neeta Sarl. Read the full credits for this episode and sign up here for a free daily newsletter from The Conversation.

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