Abstract: This disclosure provides methods of treating or, reversing, and/or eliminating obsessive-compulsive disorder (OCD) in a subject by administering to the subject a dose of a 5-HT receptor agonist such as psilocybin. The method can significantly reduce or eliminate the symptoms of OCD with a single dose of a 5-HT receptor agonist, an effect that can last at least 12 weeks.

Abstract: One aspect of the invention provides a method of treating a subject diagnosed with one or more mental disorders selected from the group consisting of: anxiety disorders, mood disorders, trauma-associated disorders, psychotic disorders, and obsessive-compulsive disorder and related disorders. The method includes: performing near-infrared spectroscopy (NIRS) imaging of one or more regions of interest in the subject's brain; presenting a representation of the NIRS imaging to the subject; and while continuing to perform the performing and presenting steps: presenting a stimulus of anxiety or other symptomatology to the subject; instructing the subject to increase activity in the one or more regions of interest; and instructing the subject to decrease activity in the one or more regions of interest.