Distinct regional age effects on [11C]AZ10419369 binding to 5-HT1B receptors in the human brain

Abstract Purpose Age-related changes in the serotonin system have been described, and proposed to be associated with behavioral changes observed particularly in the elderly population. The 5-HT 1B receptor is thought to have a regulatory role in a number of physiological functions, and has been implicated in several age-related diseases. The purpose of the present study was to examine if the availability of 5-HT 1B receptors is decreasing with age in healthy subjects. Methods Data from five previous studies were reanalyzed and pooled, generating data from fifty-one healthy subjects, age 20 to 70, that had been examined with positron emission tomography (PET) and the 5-HT 1B specific radioligand [ 11 C]AZ10419369 at baseline conditions. The binding potential ( BP ND ) in cortical and subcortical areas was calculated using the simplified reference tissue model (SRTM). After correction for partial volume effects (PVEc), the correlation between age and regional BP ND was examined. Results A statistically significant negative correlation between age and BP ND was obtained for neocortical regions and the ventral striatum (VST). The average reduction in BP ND per decade was 8% in cortex and 4% in VST. The BP ND in the caudate nucleus and the putamen was mainly unaffected by age. Conclusion The 5-HT 1B receptor availability decreases by age in cortical regions, whereas it remains stable in the caudate nucleus and putamen. By consequence, age-matching of control subjects will be necessary in future clinical studies.