A week or so ago, I found myself in a conversation about the nature of mental health diagnosis. I've always found it interesting how no one is "hysterical" any more -- if you read books on psychology from a few decades ago, there's a great deal of discussion about that condition, where as it seems that now it's almost never discussed. I've always taken that as an indicator of how at least part of the concept of "mental illness" is a social construction.
However, I stumbled across this abstract of a paper in the journal Social Science & Medicine, which notes "Experimental and clinical studies of nonhumans and humans reveal somatic and behavioral effects of hypervitaminosis A which closely parallel many of the symptoms reported for Western patients diagnosed as hysterical and Inuit sufferers of pibloktoq ['arctic hysteria']. Eskimo nutrition provides abundant sources of vitamin A and lays the probable basis in some individuals for hypervitaminosis A through ingestion of livers, kidneys, and fat of arctic fish and mammals, where the vitamin often is stored in poisonous quantities." [emphasis added. -tms]
Excessive vitamin A is well known to be toxic, and can result in birth defects, liver abnormalities, and CNS disorders. There's also some evidence linking excessive intake with osteoporosis, but the picture is not clear.