This study tested a new method called the alpha-synuclein seed amplification assay (SAA) to help distinguish Lewy body dementia (LBD) from Alzheimer’s disease and other conditions. Researchers worked with 398 patients from memory clinics in Montpellier, Nimes, and Perpignan, using spinal fluid and blood samples along with cognitive assessments.
The SAA test was positive in 19 out of 20 patients with LBD, showing high sensitivity for detection. It also identified alpha-synuclein pathology in about 16% of patients with Alzheimer’s disease. The test showed strong diagnostic performance, with 95% sensitivity and 93.5% specificity for distinguishing LBD from patients without LBD or Alzheimer’s.
Patients who tested positive on the SAA had lower cognitive scores and other biological changes, such as lower CSF Aβ42/40 ratios and higher plasma GFAP. However, the study did not report safety data, and it was an observational cohort study, so it shows associations, not cause-and-effect.
The main reason to be careful is that this is an early, practice-relevant finding from a single clinical setting. It suggests the SAA could improve diagnosis, but more research is needed before it becomes routine.