Resting state fMRI reveals differential effects of glucose administration on central appetite signalling in young and old adults

Abstract

BackgroundHealthy aging has been associated with reduced appetite and energy intake, which can lead to loss of bodyweight and undernutrition and related health problems. The causes for the decline in caloric intake are multifactorial involving physiological and non-physiological processes. AimsHere we examined age-related, physiological changes in brain responses associated with macronutrient intake. MethodsUsing a randomized, double blind, balanced cross-over design, younger (n=16, aged 21-30) and older adults (n=16, aged 55-78) received a drink containing glucose and a taste-matched placebo after an overnight fast. Blood glucose and hunger were assessed at baseline and 20 minutes post-ingestion, after which participants underwent resting state functional magnetic resonance imaging (rsfMRI). ResultsFrequency dependent changes in slow-5 (0.01-0.027Hz) and slow-4 (0.027-0.073Hz) amplitude of low frequency fluctuations (ALFF) and fractional ALFF (fALFF) of the blood oxygen level-dependent (BOLD) signal were contrasted between sessions and age groups. We observed a significant treatment x age-group interaction in slow-5 ALFF and fALFF in the left insula. Younger participants showed a decrease in BOLD amplitude, whereas older participants showed an increase. We further observed a treatment x age-group interaction in slow-4 ALFF in the occipital and lingual gyrus and precuneus with older participants showing an increase in magnitude of slow-4 ALFF and younger participants showing a decrease in the same measure. ConclusionThese age-related, frequency-dependent changes in the magnitude of the BOLD signal in a key region related to energy homeostasis following feeding may contribute to behavioral changes in energy intake during senescence.