A comprehensive, systematic, and advanced review of the scientific, preclinical, and clinical aspects of several major mental illnesses. The illnesses covered range from neurological disorders including Alzheimer's disease, Huntington's disease, and Parkinson's disease, to psychiatric disorders including schizophrenia, autism spectrum disorders, Tourette's syndrome and tic disorders, obsessive-compulsive disorder, unipolar depression, bipolar disorder, and attention deficit hyperactivity disorder. For each disorder, the authors uniformly discuss its incidence and prevalence, etiology, molecular targets and mechanisms of action, brain structures and pathways, animal models, signs and symptoms, genetics, treatments, and related medical terminology.