DRD1 and attention deficit-hyperactivity disorder: PPI networks and topological property functions identified possible core targets for LMQXM treatment of ADHD, mainly involving the dopaminergic system (such as DRD1, DRD2, SLC6A3, MAOA, and MAOB), noradrenergic system (such as SLC6A2), and serotonergic system (such as SLC6A4, HTR1B, HTR1A, HTR2A, HTR3A, and HTR2C), whose mechanisms of action are closely related to the transmission of monoamine neurotransmitters, most of which have been classified as risk genes for ADHD (Lasky-Su et al., 2008; Banaschewski et al., 2010).