Movement disorders are a heterogeneous group of conditions that are related by signs and symptoms involving voluntary and involuntary motor actions. Diseases included are well-known disorders such as Parkinson’s disease (PD), Huntington’s disease, and Gilles de la Tourette syndrome and also many other uncommon conditions. Movement disorders are generally divided into two broad clinical groups, the akinetic-rigid syndromes and the hyperkinetic syndromes. Patients with movement disorders unite the practice of neurology and psychiatry because of their overlap of symptoms. Affective, behavioral, cognitive, and perceptual problems may occur in many different movement disorders. The chapter addresses mesolimbic dopamine system that by virtue of its unique connections with portions of the cerebral cortex, basal ganglia, and other subcortical nuclei, is an important circuit uniting different types of symptoms and disorders. Depression is the most common nonmotor symptom in PD.