This book intend to provide therapeutic management of Parkinson disease.Cognitive impairments are commonly present in most of the neurological disorders. Few of them are multiple sclerosis, post stroke cases, Alzheimer's disease, and in geriatric population.To evaluate the diurnal changes in cognitive abilities of patients with PD Over the course of the day.In the present study it can be concluded that, there is diurnal variations present in the subjects with Parkinson's seeing that there were significant variations in the scores of the patient on the cognitive rating scale from morning to afternoon