GDF15 and Parkinson disease: Based on this knowledge about GDF15 and MMP9 in acute and chronic brain conditions with and without dopaminergic loss and neurodegeneration, we set out to measure CSF levels of these two proteins in a large cohort of Lewy body disorders, i.e. Parkinson’s disease without (PD no dementia, PDND), PD with dementia (PDD) and dementia with Lewy bodies (DLB), to determine their associations with demographical, clinical and routine CSF parameters.