Trichotillomania is a chronic mental disorder characterized by recurrent hair-pulling. Hoarding, excoriation and trichotillomania are classified as obsessive-compulsive related disorders in DSM-5, which share similar clinical presentations, characterized by inappropriate and excessive repetitive behaviors and dysregulation of inhibitory control processes. Research evidence suggests that abnormalities in the cortico-striato-thalamic-cortical circuits are one of the key factors underlying the pathophysiology of obsessivecompulsive related disorders, including trichotillomania. Glutamate is the primary neurotransmitter within the cortico-striato-thalamiccortical circuits. Therefore, the use of glutamate-modulating agents is subject to interest for obsessive-compulsive related disorders. N-acetylcysteine, a derivate of the amino acid L-cysteine, has been explored as potential therapy for obsessive-compulsive related disorders, including trichotillomania. Pharmacotherapies that target the prefrontal glutamatergic system, such as N-acetylcysteine, may correct the underlying pathophysiologic abnormalities and symptoms of trichotillomania. Even a limited number of studies are suggesting that N-acetylcysteine is a promising treatment option, these studies did not assess treatment effects exceeding 3-4 months treatment period. Longer term effects of N-acetylcysteine therapy in trichotillomania require further evaluation.

In this article, has been discussed the characteristics that make knowledge unforgettable. The attention has been attracted to the role of the involvement of multiple brain layers, locations and connections, in learning and performing process. It is sustained that “learning and performing are systemic issues” and proposed that “a successful learning and performance is directly proportional to the sum of created appropriate personal ties – created personal functional connectomes - in the entirety of the central nervous system” and the “strength or weakness of a learned material is directly proportional to the quantity, quality and intensity of the ties made within the entire Central Nervous System Network”. In other terms; the more brain parts are involved the better is learned and performed. And, it has been outlined that “the same fact is the explanation of why in different subjects, the memory storages are relatively in different localities, and in vague concentrations.”