[CtEkM8Vq]

Well it is said that breathing gradually stops as meditation goes deeper. You can even experience your breathing becoming shorter and smoother as you meditate. However, I have never heard this causing any brain damage whatsoever. If it causes such then I am not sure how people who have been meditating for long hours still wake up in perfect shape or in better shape So chances are high that you have been misinformed.

As for going crazy and all that, meditation in general is not only Buddhist meditation as Aloka-D pointed out. Not sure why correct practice of Buddhist meditation will make a person crazy. Never heard of it.

In case if you haven't done so already, I suggest you read these; written by two Thai Forest monks based on their own personal experiences

1) The Ajhan Brahm's book : Mindfulness, Bliss and Beyond
2) Anapanasati: Mindfulness of Breathing by Buddhadasa Bhikku : http://www.what-buddha-taught.net/