Plasma (S)24‐OH‐cholesterol (possibly reflecting brain cholesterol metabolism) is inversely linked to Parkinson disease (PD), is relatively stable over time, and may serve as a new biomarker for PD, according to a recent study. 60 PD patients and 64 controls were recruited from an academic movement disorder clinic (2009–2012). 35 PD patients and 33 controls returned approximately 36 months later. Fasting plasma (S)24‐OH‐cholesterol (brain‐derived cholesterol metabolite) and 27‐OH‐cholesterol (peripheral cholesterol metabolite) were quantified. Researchers found:

• Mean age of PD subjects was 63.8 ± 8.3 years and disease duration was 5.0 ± 5.4 years.
• Plasma (S)24‐OH‐cholesterol levels were inversely associated with the odds of having PD, with an odds ratio of 0.92 for each 1‐ng/mL increase.
• Compared to the lowest tertile, the odds ratio was 0.34 for the second tertile and 0.08 for the highest tertile.
• Higher (S)24‐OH‐cholesterol levels also were correlated with better sense of smell (r=0.35).
• No significant associations were found between clinical measures and 27‐OH‐cholesterol, a peripheral cholesterol metabolite.
• Furthermore, (S)24‐OH‐cholesterol levels were stable over time, whereas 27‐OH‐cholesterol decreased with time in both cases and controls.