growing elderly population is increasing the number of persons with late-onset diseases such as Parkinson’s disease (PD) and Alzheimer disease (AD) throughout the world. These two diseases are not related but they do have some similarities. Both are neurodegenerative diseases and typically begin late in life. Both are characterized clinically by slow and progressive disease course and pathologically by neuronal degeneration with intra neuronal inclusions. Although initial symptoms differ, both diseases lead to dementia.
Apart from these apparent similarities, two diseases are completely different. PD is primarily a movement disorder that can eventually develop cognitive impairment and dementia characterized by visuospatial impairment and fluctuations in mental state. However, many individuals with PD never develop cognitive impairment during the course of their illness.