December 6, 2025

@michaelokun

Could serum p-tau217 signal early cognitive trouble in REM sleep behavior disorder? Phosphorylated tau is a brain protein that becomes elevated when nerve cells are stressed or degenerating. Shijun Yan and colleagues describe in a new paper in Annals of Neurology how serum p tau217 may help predict which folks w/ idiopathic REM sleep behavior disorder will be more likely to develop later thinking problems. Key Points: - Serum p tau217 rises in iRBD folks w/ early cognitive impairment and tracks w/ lower MoCA scores showing it reflects subtle brain changes. - High p tau217 predicted progression to Parkinson’s disease w/ cognitive impairment or predicted dementia w/ Lewy bodies. - Those in the top quartile had an eightfold higher risk of phenoconversion. - NfL did not predict cognitive decline, however NfL was markedly elevated in those who later developed multiple system atrophy. My take: We are starting to appreciate the many potential uses of the powerful biomarker p tau217 and we are beginning to appreciate its use in the setting of REM sleep behavior disorder. Here are 5 points that resonated w/ me about this new article. 1- Blood biomarkers are opening a window into brain health, even years before a diagnosis is made. 2- Elevated p tau217 in REM sleep behavior disorder may flag added Alzheimer type changes which can shape the risk of future memory issues. 3- Not every biomarker is useful for every condition however p tau217 seems to outperform NfL for predicting thinking problems. 4- Higher p tau217 levels increase the likelihood of developing dementia w/ Lewy bodies or Parkinson’s w/ cognitive impairment which may help guide earlier intervention. 5- These findings support a potential future where routine blood tests could one day stratify risk, guide monitoring and inform counseling. https://onlinelibrary.wiley.com/doi/10.1002/ana.78109 #michaelokun #parkinson #fixelinstitute