High Availability of the α7-Nicotinic Acetylcholine Receptor in Brains of Individuals with Mild Cognitive Impairment: A Pilot Study Using 18F-ASEM PET

Emerging evidence supports a hypothesized role for the alpha 7-nicotinic acetylcholine receptor (alpha 7-nAChR) in the pathophysiology of Alzheimer's disease. F-18-ASEM (3-(1,4-diazabicyclo[3.2.2]nonan-4-yl)-6-F-18-fluorodibenzo[b,d]thiophene 5,5-dioxide) is a radioligand for estimating the availability of alpha 7-nAChR in the brain in vivo with PET. Methods: In this cross-sectional study, 14 patients with mild cognitive impairment (MCI), a prodromal stage to dementia, and 17 cognitively intact, elderly controls completed F-18-ASEM PET. For each participant, binding in each region of interest was estimated using Logan graphical analysis with a metabolite-corrected arterial input function. Results: Higher F-18-ASEM binding was observed in MCI patients than in controls across all regions, supporting higher availability of alpha 7-nAChR in MCI. F-18-ASEM binding was not associated with verbal memory in this small MCI sample. Conclusion: These data support use of F-18-ASEM PET to examine further the relationship between alpha 7-nAChR availability and MCI.