Improving Early Recognition of Treatment-Responsive Causes of Rapidly Progressive Dementia: The STAM₃P Score

Objective: To improve the timely recognition of patients with treatment-responsive causes of rapidly progressive dementia (RPD). Methods: A total of 226 adult patients with suspected RPD were enrolled in a prospective observational study and followed for up to 2 years. Diseases associated with RPD were characterized as potentially treatment-responsive or non-responsive, referencing clinical literature. Disease progression was measured using Clinical Dementia Rating® Sum-of-Box scores. Clinical and paraclinical features associated with treatment responsiveness were assessed using multivariable logistic regression. Findings informed the development of a clinical criterion optimized to recognize patients with potentially treatment-responsive causes of RPD early in the diagnostic evaluation. Results: A total of 155 patients met defined RPD criteria, of whom 86 patients (55.5%) had potentially treatment-responsive causes. The median (range) age-at-symptom onset in patients with RPD was 68.9 years (range 22.0–90.7 years), with a similar number of men and women. Seizures, tumor (disease-associated), magnetic resonance imaging suggestive of autoimmune encephalitis, mania, movement abnormalities, and pleocytosis (≥10 cells/mm³) in cerebrospinal fluid at presentation were independently associated with treatment-responsive causes of RPD after controlling for age and sex. Those features at presentation, as well as age-at-symptom onset <50 years (ie, STAM₃P), captured 82 of 86 (95.3%) cases of treatment-responsive RPD. The presence of ≥3 STAM₃P features had a positive predictive value of 100%. Interpretation: Selected features at presentation reliably identified patients with potentially treatment-responsive causes of RPD. Adaptation of the STAM₃P screening score in clinical practice may minimize diagnostic delays and missed opportunities for treatment in patients with suspected RPD. ANN NEUROL 2024;95:237–248.