IGF1 and schizophrenia: In some of them, peripheral IGF‐1 levels were reported to be lower in schizophrenia patients (Chao et al., 2020; Venkatasubramanian et al., 2007; Wu et al., 2008), while other studies either found higher levels (Chen et al., 2021) or no difference (Demirel et al., 2014; Okamoto et al., 2021; Teja, 2018) compared to healthy controls.