CSF GAP-43 as a biomarker of synaptic dysfunction is associated with tau pathology in Alzheimer’s disease

The present study showed that CSF GAP-43 was elevated in the clinical AD dementia group and in tau positive individuals. CSF GAP-43 was correlated with CSF p-tau, CSF t-tau and plasma p-tau. CSF GAP-43 levels were much higher in the tau positive group compared to the tau negative group, which distinguished tau positive status from tau negative status. The 2018 AD research framework proposed a biomarker classification system called the Aβ/tau/neurodegeneration (AT(N)) system, which defined AD as an AD continuum based on core neuropathological changes in vivo²⁵. If only an Aβ abnormality was present (A+T–N–) this would put the individual at a place on the AD continuum called AD pathological change. If both Aβ and tau abnormalities were present, but neurodegeneration was absent (A+T+N–), the individuals could be considered as having AD even without exhibiting signs of…