CYP46A1 and neurodegenerative disease: Parkinson's disease (PD): when measured as the total metabolite (sum of non-esterified and esterified), 24-HC is found to be elevated in CSF from patients with different neurodegenerative diseases [54], possibly as a result of release from dying neuronal cells, or alternatively as a consequence of CYP46A1 metabolism of released cholesterol from these cells.