This study investigates the causal relationships between 18 neurodegenerative and neuropsychiatric disorders and Alzheimer's Disease (AD) using Mendelian randomization (MR) analysis. The authors found that bipolar disorder (BD), migraine, schizophrenia, and Parkinson's disease (PD) are causally associated with an increased risk of AD, while attention-deficit/hyperactivity disorder (ADHD) is associated with a decreased risk. Additionally, there is suggestive evidence of a causal effect of amyotrophic lateral sclerosis (ALS) and Tourette's syndrome on AD. The study suggests that genetic components predisposing to BD, migraine, schizophrenia, and PD may contribute to the development of AD, while ADHD may reduce the risk. The findings highlight the potential for early interventions in neuropsychiatric diseases to influence the risk of AD-related cognitive decline. The study also discusses the complex genetic relationships between neurodegenerative and neuropsychiatric diseases, emphasizing the need for further research to understand the shared underlying mechanisms.This study investigates the causal relationships between 18 neurodegenerative and neuropsychiatric disorders and Alzheimer's Disease (AD) using Mendelian randomization (MR) analysis. The authors found that bipolar disorder (BD), migraine, schizophrenia, and Parkinson's disease (PD) are causally associated with an increased risk of AD, while attention-deficit/hyperactivity disorder (ADHD) is associated with a decreased risk. Additionally, there is suggestive evidence of a causal effect of amyotrophic lateral sclerosis (ALS) and Tourette's syndrome on AD. The study suggests that genetic components predisposing to BD, migraine, schizophrenia, and PD may contribute to the development of AD, while ADHD may reduce the risk. The findings highlight the potential for early interventions in neuropsychiatric diseases to influence the risk of AD-related cognitive decline. The study also discusses the complex genetic relationships between neurodegenerative and neuropsychiatric diseases, emphasizing the need for further research to understand the shared underlying mechanisms.