Well thankfully I'm not, but even if I were I think that's a bit of a stretch. A materialist acknowledging an effect he cannot quantify or directly observe is not much of a materialist.
My point was that if there's only matter, then mental / psychological harm must be in some sense physical harm.
(FWIW I lean not-materialist myself, but it's a common perspective around here so I thought it was worth pointing out)