The purpose of this study was to investigate whether cerebrospinal fluid (CSF) levels of tau, phosphorylated tau, β‐amyloid42, α‐synuclein, neurofilament light, and YKL‐40 change over time and if changes correlate with motor progression and/or cognitive decline in patients with PD and controls. This evidence concerns the gene CHI3L1 and Parkinson disease.