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Updated: Jul 14, 2026

Hybrid PET/MRI Imaging of Alzheimer's Disease Based on 18F-AV-1451
Published on: April 18, 2025
A positron emission tomography study of 5-hydroxytryptamine-1A receptors in Alzheimer disease
Krista L Lanctôt1, Doug F Hussey, Nathan Herrmann
1Neuropharmacology Research Program and Geriatric Psychiatry, Toronto, Ontario, Canada. Krista.Lanctot@sunnybrook.ca
Objective:
The important role of serotonin-1A (5-hydroxytryptamine-1A [5-HT(1A)]) receptors in cognition, behavior, and drug response is increasingly being recognized. Postmortem studies suggest decreased 5-HT(1A) receptors in patients with Alzheimer disease (AD), but this has not been confirmed in vivo. Our primary objective was to assess the extent of 5-HT(1A) receptor losses in mild to moderate AD.
Methods:
The authors examined 5-HT(1A) receptors in 10 patients with mild to moderate AD and 10 healthy volunteers with the same sex and similar age using positron emission tomography imaging with the selective 5-HT(1A) receptor radioligand, [(11)C]WAY-100635. Regions of interest (ROIs) were manually drawn on coregistered magnetic resonance images for the frontal, lateral temporal, medial temporal (MTC), parietal, and cerebellar cortices. Using the simplified reference tissue model, 5-HT(1A) binding potentials (BPs) were calculated relative to the cerebellum.
Results:
After adjusting for partial volume effects, ROI analysis showed a significant group effect (AD versus comparison group) on BP. Analysis of between-subjects factors showed significantly decreased 5-HT(1A) BP in the right MTC, but not in the other ROIs.
Conclusion:
Given the strategic role of these receptors, loss of right medial temporal 5-HT(1A) receptors might play an important role in AD symptomatology.
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