Do you lose brain cells when you hit your head?

March 21, 2008 6:36 PM

When you hit your head, do you lose brain cells? If so, how many? Also can you get them back? If yes, how?

Sorry if this is an elementary question but I've never found out whether this is just a myth or not. Do you really lose 10,000 brain cells everytime you hit your head? Can, and how do you regenerate these brain cells?

posted by meta.mark to health & fitness (8 comments total)

Yes, you can regenerate brain cells.
posted by mpls2 at 6:54 PM on March 21, 2008

Generally, no you don't lose any.

It depends on the type of injury and how severe. When you suffer a concussion, it's believed that there is a massive depolarization of neurons leading to unconsciousness. So a full recovery is expected. Contusions are more serious, involving some swelling and some cellular loss. Usually more serious injuries will have components of acceleration/deceleration injuries, and then there is shearing of axons as well.

There are only a couple of places in the brain with stem cells, and they aren't really able to migrate. So when you lose cells you don't get them back. But the brain is able to adapt quite well. That's a pretty watered version, but hey, it's late and I'm tired. Hope that answers your question.
posted by sero_venientibus_ossa at 6:55 PM on March 21, 2008

I'm going to go with,yes you lose brain cells. You also lose skin cells while typing, and stomach cells while digesting. But... you regenerate all of those. Individual cells are relatively delicate, and it would be silly to think an impact wouldn't harm at least some to the point they are "destroyed". In the larger scale of the human, it doesn't matter in the least. You have so many, and such a tiny portion get destroyed, that nothing notices. We are wonderfully redundant.
posted by cschneid at 7:24 PM on March 21, 2008

Hitting your head hard enough can cause permanent brain damage. The "10,000" figure is meaningless because I assume it would vary based on how hard one is hit. But yeah, watch out.
posted by 1 at 8:33 PM on March 21, 2008

IANAN, but my understanding is that with minor/moderate concussive jolts to the head interfere with neural connections rather than the cells themselves. So, if one has redundant connections to information (many associations leading to the same thing) then one won't notice if a few get disrupted and if a memory is accessed it generally reforms new associations in relation to the thing it is referencing.
posted by Burhanistan at 8:34 PM on March 21, 2008

I am an epically clumsy bicyclist and motorcyclist. In the past twenty years I've had amnesia (and for those who don't know, amnesia is WEIRD) twice and have been knocked unconscious twice. I don't believe I've suffered permanent damage in terms of memory or cognition.
posted by sourwookie at 12:17 AM on March 22, 2008

Every day you lose brain cells just by the process of aging. Growing new brain cells may or not help you. New brain cells don't help old memories although they help to foster pathways for new memories. As I understand it the problem is not in brain cells themselves but in the synapses. If you are not "exercising" the brain to create new synapses then you could grow two brains for all the good it will do you.

A quick search on Google seems to indicate that head trauma can directly affects the axons and synapses. The axon is part of the brain cells. I didn't quite catch if those were able to be regenerated. Synapses can be regrown but they require thought....
posted by JJ86 at 5:37 AM on March 22, 2008

Notwithstanding the wikipedia examples (olfactory and hippocampal) the general belief right now is that CNS neurons don't regenerate -- (although there's obviously a ton of research into whether/how we might see better outcomes). The way I understand it, the combination of greater distances, changed repellant/attractant and morphogenic signals, and lack of embryonic growth factors mean that the regenerating axon wouldn't be able to find the appropriate endpoint in the adult CNS..

As for the damage caused by whacking your head, I'm not really sure.. anything that caused enough swelling or vascular leakage could lead to occlusion of blood flow to an area and secondarily lead to ischemia and neuronal death? But honestly, I think that's got to be a really decent blow to the head.
posted by BundleOfHers at 10:08 AM on March 22, 2008