This study investigates the causal relationship between immune cells and neurodegenerative diseases (NDs) using a two-sample Mendelian randomization (MR) analysis. The researchers analyzed 731 immune cell features and four NDs: Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). The study employed various MR methods to minimize bias and obtain reliable estimates of the causal relationship between immune cells and NDs. The results identified potential causal relationships between specific immune cells and each ND. Specifically, 8 types of immune cells were found to have potential causal relationships with AD, 1 type with PD, 6 types with ALS, and 6 types with MS. The study provides valuable insights into the complex interactions between immune cells and NDs, offering potential targets for future clinical research and treatment strategies. However, the study has limitations, including the restriction to European participants and the need for further validation in other populations.This study investigates the causal relationship between immune cells and neurodegenerative diseases (NDs) using a two-sample Mendelian randomization (MR) analysis. The researchers analyzed 731 immune cell features and four NDs: Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). The study employed various MR methods to minimize bias and obtain reliable estimates of the causal relationship between immune cells and NDs. The results identified potential causal relationships between specific immune cells and each ND. Specifically, 8 types of immune cells were found to have potential causal relationships with AD, 1 type with PD, 6 types with ALS, and 6 types with MS. The study provides valuable insights into the complex interactions between immune cells and NDs, offering potential targets for future clinical research and treatment strategies. However, the study has limitations, including the restriction to European participants and the need for further validation in other populations.