Autoimmune Encephalitis Is the Most Common Treatment-Responsive Cause of Rapidly Progressive Dementia; a Large Dutch Prospective Cohort Study.
Robin van Steenhoven1, Daniëlle Bastiaansen1, Juna de Vries1, Frank Jan de Jong1, Nihal Satyadev2, Juliette Brenner1, Jeroen Kerstens1, Yvette Crijnen1, Peter Sillevis Smitt1, Gregory Day2, Harro Seelaar1, Maarten Titulaer1
1Neurology, Erasmus University Medical Center, 2Neurology, Mayo Clinic Florida
Objective:
Determine the frequency of autoimmune encephalitis (AE) in patients with rapidly progressive dementia (RPD) and validate the STAM3P score, designed for early recognition of treatment-responsive causes of RPD.
Background:
RPD presents a great clinical challenge due to the broad differential diagnosis and limited time to act. Early diagnosis is essential, as underlying disorders might be treatment-responsive.
Design/Methods:
In this prospective, multicenter cohort study, we included adult patients between December 2019 and September 2024 diagnosed with RPD, defined as cognitive deterioration resulting in interference in functioning <1 year. Serum and CSF were tested for neuronal and glial autoantibodies. Patients were evaluated according to the STAM3P score (seizures, tumor, age <50 years, mania, movement disorders, MRI findings of AE, and pleocytosis >10 cell/mm3).
Results:
In total, 135 patients were included (46% female, median age 67 years), including 88 (65%) with treatment-responsive disorders. AE represented the largest treatment-responsive subcategory (54/88;61%; 40% of total cohort). Most frequent subtypes were LGI1 (19/54;35%), NMDAR (8/54;15%), seronegative AE (8/54;15%) and GFAP (7/54;13%). Other treatment-responsive categories included inflammatory disorders (16/88;18%), metabolic/toxic causes (5/88;6%) and psychiatric disorders (4/88;5%). Of 67/70 (96%) patients with AE and inflammatory disorders treated with immunotherapy and followed for two years, 59 (88%) showed clinical improvement. Creutzfeldt-Jakob disease was the most common non-responsive diagnosis (15/47;32%; 11% of total cohort). Increasing STAM3P scores showed decreasing sensitivity and increasing specificity. A STAM3P score of ≥1 captured almost all treatment-responsive diagnoses (95% specificity; 40% sensitivity), while every patient with a STAM3P score of ≥3 had RPD due to autoimmune or inflammatory causes (27% sensitivity).
Conclusions:
Treatment-responsive disorders are common in RPD, with AE and inflammatory disorders representing most frequent categories. A STAM3P score of ≥1 is useful for identification of treatment-responsive disorders and subsequent directed investigations, whereas the presence of ≥3 STAM3P features is highly specific and applicable for early treatment decisions.
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