The onset of Alzheimer’s disease may share the plot of Captain America: Civil War. (No spoiler).
Stay with me on this: A study, done at Harvard, proposed a startling hypothesis – the plaques of beta amyloid that are the hallmark of dementia may actually be an immune response. The idea is that beta amyloid proteins are released by the brain during an infection and form around invading bacteria, capturing them in a web of goo that looks strikingly similar to the way Spiderman captures a bad guy.
To test this, the scientists injected bacteria directly into the brains of mice. The mice formed Alzheimer’s plaques as a response, and at the center of each plaque was a single bacteria, trapped in its sticky web. The plaques had saved the brain from the bad guys, but – as with a crisis averted by Spiderman or another Avenger – not without leaving the area riddled with collateral damage.
So what happens if your brain doesn’t have a superhero to protect it? The scientists ran the same test on “knock-out” mice, genetically engineered to produce no amyloid protein. The brains of the mice were exposed to bacteria, yet contained no plaques. But these mice were far more likely to die of infection, defenseless against the marauding villains.
If Alzheimer’s is actually produced on purpose, as a defense mechanism against bacteria, then doctors would be left with the conundrum from the plot Captain America Civil War — treating the condition might involve getting rid of the superheros, leaving patients vulnerable to attack. We are damaged either way.
Yet there is hope, as the hypothesis opens up new avenues for prevention – if we can tighten up the blood-brain barrier in the elderly, we may prevent the infections that cause release of amyloid in the first place. Prevention is better than treatment, hands down.
But if we can’t prevent it, we need to train Spiderman to clean up his act. It happens in the movies; maybe we can pull it off in real life too.