Note On Psychiatric Symptoms From Vitamin A and Related Compounds

I was going to mention that, in reference to my last two postings, that an excess of vitamin A and some retinoic acid derivatives could, in my opinion and in the opinions of others, produce psychiatric symptoms without elevating the intracranial pressure. But using lumbar punctures to test the CSF pressure is a crude and, from a clinical or "diagnostic" standpoint, relatively insensitive approach to discerning the phenotypic state of the choroid plexus epithelial cells that constitute the blood-CSF barrier. The mechanisms underlying the apparent psychiatric side effects of retinoids (and, in my opinion, there is clearly a link) are almost totally unknown, totally mysterious. There's evidence that an excess of vitamin A can antagonize and derange the actions of vitamin D, but I don't know that that effect could account for the extreme qualities of some of these case reports with vitamin A or related compounds. They're absolutely appalling, in my opinion, and I think there's a danger of thinking of these things in excessively rigid terms. It's necessary to remember the whole "normal-pressure hydrocephalus" spectrum of neurological symptoms. As nebulous as some of those types of diagnostic categories are, there's a multitude of mechanisms that could conceivably account for the symptoms and manifestations, psychiatric or other, that characterize those "categories."