FROM JAMA NEUROLOGY

Certain cerebrospinal fluid biomarkers may help differentiate Parkinson's disease from other causes of parkinsonism and also predict which patients will later develop Parkinson's-related dementia, a report shows.

In a prospective, population-based, longitudinal study, Dr. David C. Backstrom of Umea (Sweden) University and his coinvestigators examined several biomarkers in cerebrospinal fluid (CSF) samples from 128 patients with new-onset, treatment-naive parkinsonism who resided in a defined geographic area of Sweden.

These patients agreed to CSF collection by lumbar puncture at baseline, and some agreed to serial sampling. All were followed yearly for 5-9 years, undergoing periodic comprehensive neuropsychological testing.

At their most recent follow-up visit, 104 of these participants had been diagnosed as having Parkinson's disease (PD), 11 as having multiple system atrophy, and 13 as having progressive supranuclear palsy. For reference, CSF samples were also obtained from 30 demographically similar but neurologically healthy control subjects.

High levels of neurofilament light chain protein (NFL) together with low levels of amyloid-beta 1-42 distinguished progressive supranuclear palsy from PD at baseline as well as 1 year later, after patients had been receiving dopaminergic therapy for months. Even elevated NFL alone was useful for differentiating progressive supranuclear palsy from PD: A baseline NFL exceeding 2,020 ng/L had a sensitivity of 75% and a specificity of 83% in distinguishing the two disorders. …