Hi, I'd like to help you with your question.
There is still a debate as to whether or not people can grow brain cells back. One study, done in Chapel Hill, North Carolina in 2004 and published in Science Daily noted that alcoholics, after using alcohol in excess and to the point of brain cell loss, were shown to have an increase in neuron activity after they stopped using. Their brains began to recover and normal neuron activity was noted.
There are many other studies that are geared toward understanding if brain cells can regenerate, particularly after a brain injury.
More studies are needed to understand the circumstances in which brain cells would grow back and how this would affect neuron activity. Also, since this is a new area of study, the impact on psychological disorders is not known yet.
Let me know if you have more questions or want clarification.
I hope this has helped you,