The big anti-amyloid drug that doesn’t bring Alzheimer’s? Now there’s proof

A small group of patients with mild cognitive impairment, or MCI, received a single dose of a drug that blocks a known pathway, researchers said. Another group was treated for four years with a placebo, while a third group received a placebo plus sham treatment. Over time, those treated with a drug experienced delays in memory problems.

MCI is a sign of age-related memory decline that can include disorientation, confusion and impaired memory recall, but it is not an indication of Alzheimer’s disease, the most common form of dementia.

But scientists think anti-amyloid treatments, also called beta-amyloid drugs, can slow disease progression.

“A very strong signal for someplace in the brain,” said Frank D. Toben, a neuroscientist at Harvard Medical School. “I think that’s the best way to put it.”

The study, described Wednesday in the journal Lancet, included 135 patients with mild cognitive impairment from hospitals in the U.S., Britain and France.

Those with mild cognitive impairment who were treated with anti-amyloid drugs had more significant reductions in the protein accumulation that is thought to cause dementia later in life, researchers said.

Toben’s team looked for the protein aggregates, or plaque, within a small area of the brain known as the cerebellum, a large area of the brain involved in physical and motor functioning. Those with the highest levels of plaque had the lowest memory and thinking skills two years later.

“You have two clear therapeutic avenues,” Toben said. “You can either delay the onset of memory loss or prevent the disease.”

The study has had some significant challenges. Among other things, researchers had to overcome the challenge of seeing what was happening in small clinical trials. The 3-year placebo groups showed a statistically significant delay in memory deterioration, researchers said. Those with mild cognitive impairment got less bad disease and fewer symptoms.

Many patients in Toben’s study had experienced at least six months of cognitive loss. A kind of natural experiment was to compare the effects of anti-amyloid drugs to when they were given for four years. “Nobody thought for a second we could do that in a limited period of time,” Toben said.

Toben said he hoped that similar effects could be achieved through the studies now under way on longer-term treatment with drugs, and in trials looking for the right dose and other drug combinations.

The grant came from an array of agencies including the National Institute on Aging, the National Institute of Mental Health, and the National Institutes of Health, which funds larger Alzheimer’s research grants.

Scientists hope to eventually use mild cognitive impairment to screen for and diagnose Alzheimer’s disease.

Toben said he didn’t know how much he’d spent on the study. “I will tell you we were really optimistic about it,” he said. “We were fighting very hard.”

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