YIA Winner: Brain Grey Matter Volume and Cerebral Haemodynamic and Metabolic Responses.. - Hale скачать в хорошем качестве

YIA Winner: Brain Grey Matter Volume and Cerebral Haemodynamic and Metabolic Responses.. - Hale

YIA Winner presentation at ECSS MetropolisRuhr 2017 Brain Grey Matter Volume and Cerebral Haemodynamic and Metabolic Responses to Exercise: Impacts of Age and Cardiorespiratory Fitness Hale, A.1,2, Van Lieshout, J.J.2, Gowland, P.1, Greenhaff, P.L.1,2, Francis, S.1 1: Sir Peter Mansfield Imaging Centre, (Nottingham, UK), 2: MRC/ARUK Centre for Musculoskeletal Ageing Research, (Nottingham, UK) Introduction Low cardiorespiratory fitness (CRF) is a major global risk factor for all-cause mortality (Blair et al., 1989) and CRF has been positively associated with grey matter volume in older adults (Erickson et al., 2014). Negative health traits attributed to ageing are associated with decreased physical activity levels, and can be positively modified by increased physical activity. Here, we studied healthy young and older subjects using magnetic resonance imaging (MRI) to assess: (1) changes in cortical haemodynamic responses (cerebral blood flow (CBF) and regional perfusion and oxygenation (blood oxygen level dependant (BOLD)), brain oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2) during low and moderate intensity large muscle group exercise. (2) Grey matter (GM) volume and its relationship with CRF and age. Methods 27 healthy male subjects were recruited to young (N=12, 21-27 years, BMI 23.5±1.8 kg/m2) and older (N=15, 58-74 years, BMI 23.3±2.0 kg/m2) groups. MR data was acquired at rest, during 10min of supine steady-state cycling exercise at 30% and 50% supine VO2max, and during recovery inside a 3T MRI scanner. Results At rest, there was no difference in GM volume corrected CBF between age groups. During exercise, there were clear differences in CBF, perfusion and BOLD between young and older subjects, with blunting of CBF (30% VO2max, p=0.05; 50%VO2max, p = 0.001) and perfusion (30% VO2max, p less than 0.01; 50% VO2max, p less than 0.01) responses and no clear BOLD response in older subjects. OEF was greater in older subjects compared to young across the exercise task (overall age effect p=0.0018, significant at rest and recovery (p less than 0.05)), with a trend for blunting of CMRO2 in old versus young at 50% VO2max. GM volume positively correlated with VO2max across all subjects (Pearson R=0.776, p less than 0.001). Discussion Brain cortical haemodynamic deficits with age became apparent on exercise, even after correcting for GM volume. We hypothesise that age related deficits in cardiac output, together with muscle steal on exercise, compromise brain perfusion. The trend for blunting of CMRO2 at 50% VO2max in older versus younger subjects suggests that the greater OEF in the older subjects does not fully compensate for their lower CBF at this workload. VO2max was positively related to GM volume across all ages supporting a causative association between habitual physical activity levels and/or CRF and GM volume. These findings have important implications to brain health with ageing. References Blair S et al., JAMA. 262(17):2395-401, 1989. Erickson KI, Leckie RL,Weinstein AM. Neurobiol Aging 35(2):S20–28, 2014. Contact [email protected]