[ 123 I]5‐IA‐85380 SPECT Imaging of β 2 ‐Nicotinic Acetylcholine Receptor Availability in the Aging Human Brain

Human postmortem studies have reported decreases with age in high‐affinity nicotine binding in brain. We have been investigating in vivo the availability of the β 2 ‐containing nicotinic acetylcholine receptor (β 2 ‐nAChR) in healthy nonsmokers (18–85 years of age) using [ 123 I]5‐IA‐85380 SPECT imaging. Age and regional β 2 ‐nAChR availability (V T , ) have been observed to be inversely correlated in all brain regions analyzed, with decline ranging from 21% (cerebellum) to 36% (thalamus), or by up to 5% per decade of life. Preliminary results have confirmed postmortem reports of age‐related decline in high‐affinity nicotine binding with age and may elucidate the role of β 2 ‐nAChRs in the cognitive decline associated with aging.