Effects of Age and BMI on Histamine H3 Receptor Availability in Healthy Humans

PURPOSE: To assess alterations in H3R availability with age and body mass index (BMI) in healthy humans using in vivo [¹¹C]GSK189254 positron emission tomography (PET) imaging. PROCEDURE: Twenty-four healthy individuals (2 females, 22 males; age range 20-47 years) were scanned with [¹¹C]GSK189254 with High-Resolution Research Tomograph (HRRT) or HR plus scanner. Regional VT (volume of distribution) values were computed using the two-tissue compartment model. The correlation between VT and age, BMI were examined, adjusting for relevant potential confounding effects of age or gender and injected mass. RESULTS: H3R availability (VT) was correlated with age but not BMI. VT displayed a negative correlation with age in the anterior cingulate cortex (r = -0.61, p = 0.004), frontal cortex (r = -0.50, p = 0.020), olfactory cortex (r = -0.50, p = 0.022), parietal cortex (r = -0.58, p = 0.006), cerebellum cortex (r = -0.53, p = 0.013), insula (r = -0.48, p = 0.027), putamen (r = -0.46, p = 0.034), thalamus (r = -0.45, p = 0.038), and hippocampus (r = 0.45, p = 0.039). CONCLUSION: This in vivo H3R study found a significant age-related decline in most cortical and subcortical regions.