Indeed, we have found some evidence to support our speculation in a few previous studies on several neuropsychological diseases: in depressed patients with normal levels of thyroid hormones, the addition of T3 to antidepressant drugs had some benefit in the treatment of both manic and depressed phases of mood disorders (31); application of T3 orally improved performance on a verbal fluency task in healthy subjects (32); and partial substitution of T3 for T4 led to improved neuropsychological performance and mood in patients with hypothyroidism (33). The gene discussed is TG; the disease is hypothyroidism.