Correlatively, decreased MR expression has been observed in several psychiatric disorders.17 Functionally, both pharmacological intervention studies and a genetic gain-of-function variant of MR seem to have protective effects.18–20 Therefore, we hypothesise that increasing MR activity with physiological doses of cortisol (=hydrocortisone) may prevent or substantially diminish the disrupting neuropsychiatric effects in patients with a brain tumour who receive high doses of perioperative dexamethasone, see figure 1. Here, NR3C2 is linked to psychiatric disorder.