Autism is linked to disruptions in neurotransmitter systems, including those involving glutamate, GABA, serotonin (5-hydroxytryptamine, 5-HT; Pagan et al., 2014), melatonin (Melke et al., 2008), dopamine (DA; Farook et al., 2012) and arginine vasopressin (AVP; Figure 1). Here, AVP is linked to autism.