Your hair follicles might slow down the growth if the hair is coming out but I'm not brain damaged and my brothers pulled my hair a lot as a child. On the flip side if the hair however is yanked really, really hard you could end up with a neck injury.
Of course you can't get braindamage. How? It won't rip your bones off and get your brains out. Or do you mean by shaking the head while pulling the hair. I don't think that's really damaging either.. To small children it might. It could damage you skin when yanked really hard and like tamsw said get a neck injury.
On rare occasions, where persistent & continual manual or mechanical extraction of healthy growing individual hair strains occurs, those of the blonde persuasion especially noted, had been successful removed thus creating a minute opening both through the scalp covering skin matter and the bony skull structure, two distinct and disturbing conditions occurred on an ongoing basis and with strikingly similar negative consequences as described below: 1.) The so-called gray matter, aka the brains, slowly but surely do 'leak'/escape by means of that tiny little hole in the skull region, to the point where normal conversation became endless & without good grammar. It is tragic! I CAN NOT GO ON WITH THIS HORRIBLE, HORRIBLE EXAMPLE ANY FURTHER, FORGIVE ME BUT YOU UNDER- STAND THE CONSQUENCES, DON'T YOU?
2.) Also documented profusely were the eleven cases, where in the real time the individual hair strand was so tightly entwined with functioning live brain cell contexts that instaneously IQ points were literary observed leaving the cranium. No, I will not either offend you with the details or release the very names of each of your in-laws to which this has occurred most recently. Maybe a hint, it maybe someone close to and/or connected to your wife, maybe through her mother and just maybe be a male offspring. I am not saying that that is the actual case but his wife does not talk to her sister in law, could be your wife, well not since that time they got drunk and wissed on the petunias, yes right to the left of the front door!
