CNTRL and major depressive disorder: Although we found reduced respiration and altered Ca2+ levels in MDD NPCs, the cellular ATP content was not different between the two groups ([nM/μg/ml] Cntrl 19.15 ± 4.11, MDD 18.62 ± 4.22, mean ± SEM, p = 0.69, paired t-test, two-tailed) (Fig. 2E).