The neurochemical and behavioural abnormalities expressed by NK1R-/- mice have led us to propose that a functional deficit of NK1R could contribute to ADHD in patients with polymorphism of the TACR1 gene (the human equivalent of Nk1r in rodents) (e.g. Yan et al., 2011; see also Sharp et al., 2014). This evidence concerns the gene TACR1 and attention deficit-hyperactivity disorder.