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A Vaccine for Dementia?

Suddenly, a laboratory glimpse of hope that Alzheimer’s could be reversed.

Crawford Kilian 15 Jan 2020TheTyee.ca

Tyee contributing editor Crawford Kilian blogs at The Politics of Dementia.

[Editor’s note: Over the past year, Tyee contributing editor Crawford Kilian has explored the public health issue of dementia from many angles. As he nears the end of his inquiry, he asks readers to help by sharing insights, experiences, research and resources.]

It was like an unexpected Christmas present, wrapped in medical-research terminology: a December 2019 article that seemed to offer hope of truly preventing Alzheimer’s and other dementias, rather than simply reducing the odds of developing them.

We usually think of vaccines as ways to train our immune systems to fight off infectious diseases like measles and flu; dementia seems to develop from a buildup of neurological garbage in our brains, with no bacteria or viruses involved. But we can train our immune systems to pick up garbage as well as attack invaders, and the report from the University of California at Irvine suggests a way to do just that.

The garbage in question is two kinds of proteins: beta-amyloid, or Aβ, plaques; and neurofibrillary tangles called tau. They seem to interfere with transmission of signals from one nerve cell to the next, thereby harming brain functions. Alois Alzheimer found them in the brain of Auguste Deter, a woman suffering from what we now call early-onset Alzheimer’s. Researchers have found plaques and tangles in dementia cases for over a century now, but haven’t found a way to clear out the trash that seems to cause neurodegeneration and cognitive decline.

The U.C. Irvine researchers used mice specially bred to produce Aβ and tau, and injected them with a mix of two vaccines. They wanted to see if the mice would develop antibodies to those plaques and tangles, as if they were invading bacteria. The experiment succeeded; the antibodies reduced the levels of tau and Aβ in the mice. What’s more, the antibodies “recognized senile plaques and neurofibrillary tangles/neuropil threads in human AD [Alzheimer’s disease] brain sections.”

The researchers noted that previous trials with monoclonal antibodies had failed to slow or reverse failing cognition. In effect, by the time symptoms turn up, it may be too late to reverse the damage. Prevention, not therapy, would be needed.

But the Irvine researchers had seen recent research showing that Aβ and tau strengthen each other in damaging nerve cells, and a simultaneous attack on both might have real benefits: “we hypothesize that vaccines targeting both pathological molecules simultaneously might be the most effective therapeutic approach.”

In other words, dementia might be reversed and patients could regain their memories.

That breathtaking optimism does not extend to a cure available next month. The Irvine researchers say only that “we anticipate that a simultaneous reduction of both pathological molecules may lead to a better improvement in cognitive functions, although future studies will need to carefully test this question in appropriate mouse models.” So years of further research would be needed, and likely years more of human trials, before a reliable human vaccine against dementia would be available.

As disappointing as this may be, we at least have time to work out the political implications of such a vaccine becoming real. Some are encouraging: more of us will die suddenly, of heart attack or stroke, than from dementia, after additional years of independent living. Our friends and children will be spared the burden of caring for us. Health-care costs for the elderly will be reduced.

On the other hand, those who avoid or escape from dementia will live longer, and require care for other ailments of great old age. The burden on the Canada Pension Plan will be intense when the average life expectancy soars into the 90s. The demand for housing will increase for many decades.

Those decades, of course, will also be full of other problems: climate change, mass migration, economic and political upheavals. It will be tempting to ignore Canadians with dementia and their caregivers.

We are more likely to see public health dollars aimed at climate-driven diseases and health conditions (like air pollution). Funding an expensive dementia vaccine might seem like a costly indulgence, a sentimental favour to the old folks while their grandchildren are struggling to survive.

In the meantime, while we wait for a reliable dementia vaccine, we need to research prevention as well. Maybe it will be a vaccine, but it may simply require us to eat sensibly, hit the sack and get some exercise.

For example, a recent article in Inverse magazine finds that just getting enough sleep — especially when we’re young — helps clear the brain of tau proteins. So even if you win all those all-night poker sessions and ace those last-minute overnight term papers, you’ll lose in the long term: the garbage will build up in your brain like garbage bags on the street during a collectors’ strike. And the long term, as we elders know, arrives long before we expect it to.

Similarly, people who take good care of themselves when young and middle-aged seem to be diagnosed with dementia far less often than those who abuse alcohol, smoke, get little exercise and eat food with little nutritional value. It also helps to have a lively social life, use hearing aids if needed, and avoid gum disease. Even if we still get dementia, it will likely arrive later; living well is not just the best revenge, it’s the best guarantee of a happy life.

It’s estimated that 40 per cent of dementia cases are genetic in origin. But if the Irvine vaccine could reduce plaques and tangles in mice bred to produce them, a vaccine (or vaccines) might even reverse or prevent genetically driven human cases — as well as those caused by lifestyle, concussions and other hazards.

That prospect will motivate countless researchers to explore the potential of dementia vaccines. But it will take them years if not decades to achieve true effectiveness — or to find that they’ve gone down yet another blind alley.

In the meantime, we must deal with the present cases with the resources we have, and push our governments to provide still more resources for dementia patients’ last, long journey.

This series is made possible by a grant from Bruce and Gail Macdonald. Find the rest of its pieces here.  [Tyee]

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