(Bloomberg) — Just days after Biogen Inc. revealed promising early data from an experimental Alzheimer’s treatment, new research from the Mayo Clinic may revive a long-running debate over whether the drug industry is focusing on the right target in developing therapies to treat the disease.
The study, published Tuesday in the journal Brain, found that the accumulation of dysfunctional tau protein is the real source of cognitive decline and memory loss seen in Alzheimer’s. Tau destabilizes tracks used by cells to transport food and messages throughout the brain, the research found.
Biogen’s drug BIIB037, and several others in advanced development, focus instead on the buildup of different set of protein fragments, called beta amyloid.
“Amyloid has a relationship with cognitive decline, but if you’re looking at both of them together, tau is the bad guy,” Melissa Murray, a neuroscientist at the Mayo Clinic campus in Jacksonville, Florida, said in a telephone interview. The majority of research into the disease has focused on beta amyloid over the past 25 years, she said.
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The researchers examined more than 3,600 brains from patients who died at different stages of dementia, with Alzheimer’s confirmed in almost 1,400. Measuring amyloid and tau in the brains at various stages of disease progression allowed them to conclude that it was the level of tau that predicted how quickly a person’s mental faculties had deteriorated.
Cognitive decline typically begins when abnormal tau accumulates in the memory center of the brain –-the hippocampus. Ultimately, toxic tau accumulates in the cortex, the part of the brain involved in higher levels of thinking, planning, behavior and attention, Murray said.