DRD1 and Huntington disease: In this scenario, and given the well-known role of both dopamine and histamine in synaptic plasticity and memory (Cahill et al., 2014; Ellender et al., 2011; Haas et al., 2008; Komater et al., 2005; López de Maturana and Sánchez-Pernaute, 2010; Mohsen et al., 2014; Orsetti et al., 2002; Pascoli et al., 2009; Wiescholleck and Manahan-Vaughan, 2014), it is possible that the therapeutic potential of H3R ligands as modulators of D1R-H3R heteromers could also be extended to improve learning impairments and cognitive decline in HD.