Right, but lithium is perhaps one of the more well-studied psychiatric medications, and the drug with the best evidence for its effects at mood stabilization.

The question, then is different. We know that lithium has certain theraputic effects at 0.6-1.2 mmol/L blood concentrations. In this range, it is a powerful and effective mood stabilizer. What, then, are the effects of lithium at lower concentrations?

More importantly, we dont live in a one-variable world.

I don't think this is even a dumb C vs. C scenario. My interpretation of this (and the stated "needs controlled studies in future") is that there isn't meaningful controls on the comparison - so the basic correlation seems suspect to me.

You know, as a super intelligent internet commenter :D