Wednesday, November 14, 2012

Hyperbaric Oxygen Therapy, Hippocampus Shrinkage, and PTSD (Revised)

So my local fish wrapper, the Denver Post, carried this article. http://www.denverpost.com/ci_21960079. The print version had some pretty convincing MRIs showing the vascularization of a previously damaged area of a given veteran's brain. I'll buy that. Extra oxygen lets tissues metabolize faster, and this encourages the increase of vascularity. What struck me at the time was the almost throwaway mention that oh yeah, these veterans also had reduction/elimination of their PTSD symptoms in some cases.

This caught my eye, since somewhat less recently, I read studies like this: http://www.biologicalpsychiatryjournal.com/article/S0006-3223(10)01013-9/abstract and others, which suggest that PTSD has a strong component of hippocampal shrinkage, and that antidepressant therapy with SSRIs can reverse the shrinkage and ultimately cure the PTSD. Wait, whoa, stop. Antidepressants can change your brain structure? Permanently? Yes, they can. According to the wikipedia article, (I know, I know.) SSRIs can cause the formation of new neural pathways and act as an anti-inflammatory in the brain.

My question is, are anti-depressants and HBOC doing the same thing to the PTSD sufferer? Are they revascularizing and/or reducing inflammation in the hippocampus? And if these things are possible, what else can you treat with HBOC and/or antidepressants?

Unlike what we were taught when I was in high school, our brains make new neurons every day. The difference is if we don't use them, they die. Why? I haven't read any theories about why, but I'll speculate. If you can destroy cancer by normalizing the vascularity of a cancerous tumor (http://www.sciencemag.org/content/307/5706/58.full), and if vascularity of muscle increases as the muscle becomes hypertropic, http://www.ncbi.nlm.nih.gov/pubmed/9737744, and if we can effect the vascularity of a human brain by increasing activity levels in existing brain tissue and reap the benefits of better cerebral circulation, then it stands to reason that some neurons are retained and others lost based on usage might be a result of available circulation. If you have neurogenesis in an area of your brain you use continuously, the circulation might be better, and the new neuron might stay. If it occurs where you're not using it, it might not. If that, in turn, is true, then the very act of increasing activity of existing neurons and thus causing them to demand more circulation might be not only improving circulation to existing neurons, but encouraging new neurons to replace the ones that were lost in the original brain damage.

As a mechanism, this is fascinating. How many mental diseases resemble, on their faces, parts of the brain not getting enough circulation? Can you treat, for example, depression with HBOC? Could you cure it?

Medicine is complex. As with all science, there's probably more to it than this. But circulation seems like at least the most basic, brute force tool to make permanent changes to someone's brain short of sticking an ice pick through their eye socket. And what is really fascinating is that the 'mind' changes with these structural changes. Allowing the hippocampus to regenerate relieves some forms of PTSD. Revascularizing damaged brain tissues releaves chronic pain, coordination, and yes, PTSD again in some veterans who've had head trauma. While brain chemistry is excruciatingly complex, circulation comes down to plumbing, and that's something we humans have a pretty good handle on.

Exciting stuff.

-JRS (Revised for clarity. Yesterday's version kind of fell apart at the end.)

1 comment:

Erbo said...

Maybe Michael Jackson was onto something...