Growth-associated protein 43 is associated with faster functional decline among amyloid-positive individuals with objectively defined subtle cognitive decline and mild cognitive impairment.

Objective: Objectively defined subtle cognitive decline (Obj-SCD) is an emerging classification that may identify individuals at risk for future decline and progression to Alzheimer's disease prior to a diagnosis of mild cognitive impairment (MCI). Growth-associated protein 43 (GAP-43), a cerebrospinal fluid (CSF) marker of synaptic dysfunction, has been shown to relate to an increased risk of converting to dementia, although it is unclear whether GAP-43 alterations may be detected in pre-MCI stages. Therefore, in the present study, we examined CSF GAP-43 levels among individuals with Obj-SCD cross-sectionally and also examined whether baseline GAP-43 predicts future functional decline.