A randomized controlled trial of laughter intervention on patients with schizophrenia has found differential regulation of brain-derived neurotrophic factor (BNDF) and cortisol, when significantly higher serum levels of BDNF were recorded following 8-week of simulated laughter therapy, the level of BNDF dropped following discontinuation of laughter intervention (Cheng et al., 2020). Here, BDNF is linked to schizophrenia.