This study examined the relationships between fluid and imaging biomarkers associated with memory (cerebrospinal fluid growth-associated protein 43 [CSF GAP-43] and hippocampal volume) and episodic memory performance in 586 older adults (mean age = 72.6 years, SD = 7.2) from the Alzheimer’s Disease Neuroimaging Initiative who completed CSF collection, Magnetic Resonance Imaging, and neuropsychological testing. Here, GAP43 is linked to early-onset autosomal dominant Alzheimer disease.