Successful Scene Encoding in Presymptomatic Early-Onset Alzheimer's Disease.

ABSTRACT

BACKGROUND: Brain regions critical to episodic memory are altered during the preclinical stages of Alzheimer's disease (AD). However, reliable means of identifying cognitively-normal individuals at higher risk to develop AD have not been established. OBJECTIVE: To examine whether functional MRI can detect early functional changes associated with scene encoding in a group of presymptomatic presenilin-1 (PSEN1) E280A mutation carriers. METHODS: Participants were 39 young, cognitively-normal individuals from an autosomal dominant early-onset AD kindred, located in Antioquia, Colombia. Participants performed a functional MRI scene encoding task and a post-scan subsequent memory test. RESULTS: PSEN1 mutation carriers exhibited hyperactivation within medial temporal lobe regions (hippocampus,parahippocampal formation) during successful scene encoding compared to age-matched non-carriers. CONCLUSION: Hyperactivation in medial temporal lobe regions during scene encoding is seen in individuals genetically-determined to develop AD years before their clinical onset. Our findings will guide future research with the ultimate goal of using functional neuroimaging in the early detection of preclinical AD.