Why have at least two pilots gone mad?
One of the symptoms of hypoxia is euphoria, another is belligerence. If what we have been told to believe is true, we have had two or more airbus pilots go mental within a year. That is pretty odd.
Take this incident a little further back. Why did the captain leave the cockpit? Was it a normal biology break or was he feeling sick? An older person will feel the effects of hypoxia much earlier than a younger one. In this era of personal responsiblity we tend to discount the effects of external agents on our thoughts and behaviors but such things are quite powerful.
I had an involuntary experience with an unknown drug once and one of the effects was that it made me think it would be screamingly funny to drive at high speeds down the wrong side of the road. I had a tiny sliver of rationality left and it got me home safely where I proceeded to stand on my head for awhile.
Is the air supply to the cockpit the same as that to the rest of the aircraft?