Globally, communities are burdened with significant medical and public health costs due to degenerative illnesses of the neurological system. The three main neurodegenerative disorders are amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), Huntington’s disease (HD), and Alzheimer's disease (AD). Since these illnesses are more common and more severe as people age, more instances are anticipated in the near future as life expectancy continues to climb in many nations. With few exceptions, the relative contributions of genetic and environmental variables to causation remain poorly understood. However, molecular epidemiology methods have shown promise in enhancing disease diagnosis, defining disease prognostic factors, pinpointing genes at high risk for familial neurodegenerative diseases, examining shared genetic variants that could indicate susceptibility to the non-familial forms of these illnesses, and measuring exposure to the environment. The epidemiologic characteristics of PD, AD, HD, and ALS are introduced in this literature, along with the pathophysiology of the underlying disease processes and risk factors that may eventually result in better medical therapy and disease prevention. A few suggestions for the pharmaceutical and non-pharmacological treatment of NDs are included in the chapter's conclusion.