Wednesday, February 23, 2005

Alzheimers, inflammation and the endocannabinoids

BBC NEWS | Health | Marijuana may block Alzheimer's

Or not. I read recently that headline writing is a low prestige, low paying job, in journalism. I can believe it.

Some background. The current fashion in Alzheimer's research is that local inflammation plays some role. We don't know why there's inflammation (though some think it's a response to malformed protein -- amyloid), we don't know if it's an isolated or secondary phenomena, we don't know whether (if it's secondary) it's ever an appropriate response, we don't know if stopping the inflammation will help or hurt, etc. Some of the lesions of Alzheimer's dementia or now thought to be part of the brain's appropriate response to injury; so stopping inflammation may help in the short term but be very bad in the longer term.

The microglia seem to play a role in activating this inflammation. Researchers found activating the CR2 receptor seemed to protect against the microglia-initiated inflammation triggered by amyloid protein in rats. The CR1 receptor wasn't protective. Marijuana contains a wide variety of cannabinoids; some of them activate CR1, some activate CR2, some do both, etc. CR1 mediates most of the recreational/toxic effects of marijuana.

So the headline is fun but of course quite misleading. Something in marijuana may play some role someday in something do with Alzheimer's disease. In rats, anyway.

On the other hand there are some things that we can't forget.

1. The Alzheimer's process is a condition that seems to begin quite early in life -- perhaps before age 5. It attacks almost everyone to some extent but has its greatest impact on persons with low IQs (it's very severe in people with Down's syndrome). If we can slow or remediate the onset of Alzheimer's the social impact will be vast. Our 75 yr projections for medicare and social security will look quite a bit better.

2. The discovery of the endocannabinoids and the medications that will act on them may bring a new revolution in psychiatry. Some things we'll learn will have bad effects, but I'm optimistic.

3. The role of inflammatory processes, including infectious processes, in what where thought to be "age-related" degenerative conditions of the stomach, brain and heart is quite startling. I'm quite ready now to believe we'll uncover an infections component to rheumatoid arthritis (a longstanding hypothesis that's been often investigated without success).

So this is exciting stuff, despite my kvetching on the headline.

No comments: