The brain was previously believed to be an “immune privileged” organ without an immune system. However, recent discoveries have shown a connection between the peripheral lymphatic system and the brain. This review article provides an overview of the three distinct lymphatic systems within the brain - the glymphatic, meningeal, and parenchymal systems - with a focus on the recently discovered deep brain parenchymal lymphatic vessels. The article also discusses how these lymphatic systems are regulated by various pathological conditions, including Alzheimer’s disease, Parkinson’s disease, and other neurological disorders. By shedding light on the link between these diseases and the brain lymphatic systems, the article emphasizes the importance of understanding these systems for potential therapeutic interventions to treat neurodegenerative and psychiatric disorders.