I don't know much about Spice but I know a little. Probably the greatest room for issues is that there isn't a singular Spice; there are hundreds of synthetic cannabinoids. IIRC, the first synthetic cannabinoid which made its way into drugs was actually made by Pfizer. Most Spice comes from China or India, mostly China. There are zero quality regulations and it's reasonable to assume an amount of outside contamination.
The major synthetic cannabinoids are frankenstein amalgamations of aromatic compounds, amines, and whatever else. The result is that for most synthetic cannabinoids(save for the most common ones) have no toxicological assessment and their metabolites are unknown.
As to recovering the brain- progesterone, pregnenolone, thyroid, K2, D3, Vit A, niacinamide.