Quote Originally Posted by bman420
it kills them but they are always regrowing so if you stop smoking theyll grow back theres billions of them and we dont use 90 % of them so its cool
When a brain cell is dead, its dead. Nerve cells do not continually reproduce. We have a finite number of brain cells(neurons). However, if a brain cell is damaged, it may be able to repair itself. Brain cells are not like skin cells which continually undergo cell division.

Because brain cells are continually dying, other neighboring cells compensate by forming more cell connections. The mother nerve connections, the better. An adult is more intelligent than a 12 year old not because he has more brain cells, but because through reading, experience and other forms of learning he has formed more neural connections.

Even if marijuana actually does kill brain cells, the effect is really minor if you think about it. As long as we continually keep our mind sharp by reading, learning new instruments, languages and any other activity that forms more "bridges" in our brain, then we wont become "stupid" no matter how much we smoke.