Reduced hippocampal functional connectivity in Alzheimer disease

Objective: To determine if functional connectivity of the hippocampus is reduced in patients with Alzheimer disease. Design: Functional connectivity magnetic resonance imaging was used to investigate coherence in the magnetic resonance signal between the hippocampus and all other regions of the brain. Participants: Eight patients with probable Alzheimer disease and 8 healthy volunteers. Results: Control subjects showed hippocampal functional connectivity with diffuse cortical, subcortical, and cerebellar sites, while patients demonstrated markedly reduced functional connectivity, including an absence of connectivity with the frontal lobes. Conclusion: These findings suggest a functional disconnection between the hippocampus and other brain regions in patients with Alzheimer disease.