Furthermore, in a small study involving patients with PD, it was found that α-Klotho is decreased in blood serum but increased in cerebrospinal fluid, and in the latter compartment, α-synuclein is inversely related to α-Klotho, suggesting that α-Klotho in cerebrospinal fluid is associated with the neurodegenerative process and α-Klotho in serum is related to peripheral and systemic changes [147]. Here, KL is linked to Parkinson disease.