[123I]5-IA-85380 SPECT imaging of beta2-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 beta(2)-containing nicotinic acetylcholine receptor (beta(2)-nAChR) in healthy nonsmokers (18-85 years of age) using [(123)I]5-IA-85380 SPECT imaging. Age and regional beta(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 beta(2)-nAChRs in the cognitive decline associated with aging.