RT Journal Article SR Electronic T1 Differences in Sympathetic Nervous Stimulation of Brown Adipose Tissue Between the Young and Old, and the Lean and Obese JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 372 OP 377 DO 10.2967/jnumed.115.165829 VO 57 IS 3 A1 Lonneke Bahler A1 Hein J. Verberne A1 Wanda M. Admiraal A1 Wim J. Stok A1 Maarten R. Soeters A1 Joost B. Hoekstra A1 Frits Holleman YR 2016 UL http://jnm.snmjournals.org/content/57/3/372.abstract AB Brown adipose tissue (BAT) could facilitate weight loss by increasing energy expenditure. Cold is a potent stimulator of BAT, activating BAT primarily through the sympathetic nervous system (SNS). Older or overweight individuals have less metabolic BAT activity than the lean and young, but the role of the SNS in this decline is unknown. We aimed to determine whether this lower metabolic BAT activity in older or overweight individuals can be explained by a lower SNS response to cold. Methods: This was a prospective observational study. We included 10 young obese, 11 old lean, and 14 young lean healthy men. All subjects underwent 18F-FDG PET/CT and 123I-meta-iodobenzylguanidine (123I-mIBG) SPECT/CT after an overnight fast and 2 h of cold exposure. Metabolic BAT activity was expressed as volume and as SUVmax of 18F-FDG. BAT SNS activity was expressed as volume and as the ratio between 123I-mIBG uptake in BAT and a reference region (SQUVmax of 123I-mIBG). Results: SUVmax, BAT volume, and SQUVmax were significantly different between young and old (SUVmax, 7.9 [range, 4.2–17.3] vs. 2.9 [range, 0.0–4.0]; volume, 124.8 [range, 10.9–338.8] vs. 3.4 [range, 0.0–10.9]; and SQUVmax, 2.7 [range, 1.9–4.7] vs. 0.0 [range, 0.0–2.2], respectively) (all P < 0.01) but not between lean and obese (SUVmax, 7.9 [range, 4.2–17.3] vs. 4.0 [range, 0.0–13.5] [P = 0.69]; volume, 124.8 [range, 10.9–338.8] vs. 11.8 [range, 0.0–190.2] [P = 0.64]; and SQUVmax, 2.7 [range, 1.9–4.7] vs. 1.7 [range, 0–3.5] [P = 0.69], respectively). We found a strong positive correlation between BAT activity measured with 18F-FDG and 123I-mIBG in the whole group of BAT-positive subjects (ρ = 0.82, P < 0.01). Conclusion: Both sympathetic drive and BAT activity are lower in older but not in obese men.