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is it generally best to take just one med (e.g antidepressant, adhd, anxiolytic), or is it best to take a mix of many meds, each at a lesser dosage? my intuitions seem to suggest that the latter could be better. in particular, consider the following toy model: your brain has parameters θ0 that should be at some optimal θ∗, and your loss function is a quadratic around θ∗. each dimension in this space represents some aspect of how your brain is configured - they might for instance represent your level of alertness, or impulsivity, or risk averseness, or motivation, etc. each med is some vector vi that you can add to your current state θ0, and the optimal dosage of that med in isolation is whichever quantity gets you closest to θ∗; but unless θ∗−θ0 happens to be exactly colinear with vi, you basically can't do any better just by tuning the dosage of the one med. this seems especially important because most meds don't seem to be exactly monosemantic, and also different people start out with substantially different θ0 and loss landscapes, such that you often get paradoxical reactions to meds.
I think our mental models here might be different enough that it's hard for me to understand what you're saying here. By nonlinearity here I mean that, in addition to nonlinear interactions between drugs, there are interacting systems, equilibration mechanisms, etc., to the point that I think intuitions about ML systems basically shouldn't transfer at all. But then I know your intuitions about ML are better than mine, so it's hard to be sure of that.
Re: interactions specifically, this definitely isn't true in polypharmacy situations. We know most of the ba... (read more)
I would see it more as casual learning with the do operator and so it isn't necessarily about fitting to a MSE but rather doing testing of different combinations?
Something something gears level models
5koanchuk
Changing the dose of a medication does not necessarily result in linear effects. There are nonlinearities introduced by e.g. one receptor type being saturated before another one. This phenomenon also applies to polypharmacy.
I would also like to note that θ∗ is estimated not by some objective standard, but by θ0. There's no guarantee that it remains in place as you start shifting θ.
In practice, we track our level of suffering and respond to it by trying to reduce it to acceptable levels, which is easier than trying to converge onto a hypothetical global optimum. For some, this state is reached with just one medication, for others it takes more, and for some this paradigm doesn't produce any results.