There is evidence that variations in thyroid indices or resistance to thyroid hormone may be associated with ADHD-like behavior in humans (Alvarez-Pedrerol et al. 2007; Hauser et al. 1993; Matochik et al. 1996; Stein et al. 1995), but this association has not been consistently demonstrated (Stein and Weiss 2003; Toren et al. 1997). Here, TG is linked to attention deficit-hyperactivity disorder.