SLC6A3 and attention deficit-hyperactivity disorder: The metabolism of these nutrients is crucial for brain structure development and functional maintenance (37); (2) zinc is also essential for the production and regulation of the pineal hormone melatonin which helps to regulate dopamine function and is widely recognized as a key factor in the treatment of TD (38, 39); (3) zinc can also bind to and regulate dopamine transporters, which are targets of psychostimulants for the treatment of ADHD (40).