Cerebrospinal Fluid Transforming Growth Factor β Isoforms and Disease Progression in Alzheimer’s Disease: Longitudinal Evidence from the ADNI Cohort

Background: The role of cerebrospinal fluid (CSF) transforming growth factor β (TGF-β) isoforms in Alzheimer’s disease (AD) remains unclear. We examined associations of CSF TGF-β1, TGF-β2, and TGF-β3 with AD biomarkers, neurodegeneration, cognition, and clinical progression. Methods: In 294 ADNI participants with baseline CSF TGF-β measurements, adjusted regression, and mixed-effect models were used to evaluate associations with CSF biomarkers, neuroimaging, cognitive outcomes, and conversion. False-discovery-rate correction was applied. Results: Higher baseline TGF-β1 was associated with higher CSF total tau (β = 52.68 pg/mL per 1 SD increase; q < 0.001) and p-tau (β = 5.68 pg/mL; q < 0.001). Higher TGF-β2 was associated with faster hippocampal volume loss (β = −45.42 mm3/year; q < 0.001). No isoform was robustly associated with FDG-PET decline, cognitive decline, clinical conversion, or time to conversion. Conclusions: CSF TGF-β1 and TGF-β2 show distinct associations with tau-related pathology and hippocampal neurodegeneration, respectively, but do not appear to be prognostic biomarkers of clinical progression in AD.