This eBook is the premier volume of our "Mental Illness/Central Nervous System" series, focussing specifically on "OBSESSIVE-COMPULSIVE AND RELATED DISORDERS". This eBook release encompasses diagnoses such as obsessive-compulsive disorder (OCD), body dysmorphic disorder (BDD), hoarding disorder, trichotillomania (hair-pulling disorder), excoriation (skin-picking) disorder, substance / medication-induced obsessive-compulsive and related disorders, and obsessive-compulsive and related disorder due to others. The content comprises a total of 154 "MCQs with Guiding Answers" and 198 "Linked References". This eBook also contains numerous "Study Highlights or Summary Keypoints" alongside the "CLINICAL PRACTICE INSIGHTS" section. Our primary clients include medical professionals, clinical pharmacists or PharmDs, nurses, and various other individuals in the healthcare sector, such as mentors, residents, and students. We adhere to conventional design principles for all our sequential eBook publications to circumvent the trend of "hypercoloremia mania" in eBook design. This predominantly employs the official black and white colour scheme. This publication resulted from a collaborative effort with my skilled and dedicated coauthors, namely PharmDs Najd Alyasjeen, Leen Albishawi, Eman Awwad, Dana AlTaweel, Arwa Alashqar, Kariman Hatem, Marah Hussein, Farah Qaryouti, Alia' Saidan, Duaa Alqhaiwi, and, Areej Al-Manasyeh.

Corresponding author; Clinical Pharmacy Specialty "MOH'D NOUR" BANI-YOUNES", MSc Clinical Pharmacy, BCPS, BCCCP, BCNSP, BCACP, BCIDP