[gleeaikin]

Could that be one reason for the Berserkers(sp?)

[ApplegateRanch]

The henbane and wormwood (artemisia/mugwort) might go a long way in that direction. The one is a psychedelic & poison; the other is first cousin to absinthe, with some of the same properties.

And the lactic acid rancid yoghurt taste (I first misread acetic acid) would be enough to drive anyone mad.

Then, at the end of the article:

Perhaps they’ll find out whether Roman emperor Julian, in a 1,600-year-old poem, correctly described Celtic beer as smelling “like a billy goat.”

My guess is it tasted worse than a billy goat, and the main reason the Vikings raided so savagely was in revenge for being served the stuff at their first meeting with the Celts.