Certain CSF biomarkers may help differentiate Parkinson’s disease from other causes of parkinsonism and predict which patients will later develop Parkinson’s disease-related dementia, according to research published online ahead of print August 10 in JAMA Neurology.
In a prospective, population-based, longitudinal study, David C. Bäckström, MD, of Umeå University in Sweden, and his coinvestigators examined several biomarkers in CSF samples from 128 patients with new-onset, treatment-naïve parkinsonism who resided in Sweden. These patients agreed to CSF collection by lumbar puncture at baseline, and some agreed to serial sampling. Patients were followed yearly for five to nine years and underwent periodic comprehensive neuropsychologic testing. At their most recent follow-up visit, 104 of these participants had been diagnosed with Parkinson’s disease, 11 with multiple system atrophy (MSA), and 13 with progressive supranuclear palsy (PSP). For reference, researchers obtained CSF samples from 30 healthy control subjects.
High levels of neurofilament light chain protein (NFL) together with low levels of amyloid-beta1-42 distinguished PSP from Parkinson’s disease at baseline as well as one year later, after patients had been receiving dopaminergic therapy for months. Even elevated NFL alone was useful for differentiating PSP from Parkinson’s disease: a baseline NFL exceeding 2,020 ng/L had a sensitivity of 75% and a specificity of 83% in distinguishing the two disorders. The tendency of NFL to gradually increase in PSP was even more indicative of the disease. At one year, NFL levels exceeding 2,916 ng/L had a sensitivity of 89% and a specificity of 93% for identifying PSP. CSF samples at baseline could not distinguish MSA from Parkinson’s disease, however.
In addition, an early pattern of high NFL, low amyloid-beta1-42, and high heart fatty-acid-binding protein (HFABP) predicted Parkinson’s disease-related dementia with 90% sensitivity and 71% specificity. Patients whose baseline NFL exceeded 1,100 ng/L, whose amyloid-beta1-42 was less than 626 ng/L, and whose HFABP exceeded 500 ng/L were at 2.6, 2.8, and 2.8 times higher risk of future Parkinson’s disease-related dementia, respectively, than other patients with parkinsonism.
—Mary Ann Moon