Thanks for posting this excellent article . I understand that too much dopamine excitation causes serious illness.
According to Primal Therapy's originator, Arthur Janov,(http://en.wikipedia.org/wiki/The_Primal_Scream), Dopamine is used to suppress and hide "unbearable" and unexpressed childhood (primal) pain. Illness result from this "over use" and excessive need for dopamine.
I certainly think that My PD has roots in this