Individuals with Down Syndrome (DS) commonly experience low to moderate levels of cognitive impairment and are at a high risk of developing dementia and Alzheimer's diseases (AD). Reduced cerebral blood flow (CBF) and altered CBF characteristics have been observed in the aging population without DS and has shown to have detrimental effects on cerebral microvasculature, which may increase the risk of developing dementia and AD. However, differences in CBF and its characteristics between individuals with and without DS and its response to exercise have not been studied.PurposeTo examine the differences in CBF and its characteristics following a 20‐minute bout of moderate intensity walking in individuals with and without DS.MethodsThirty‐eight young (DS=19, Age=25 yrs) individuals with and without DS participated in this study. Changes in mean middle cerebral artery velocity (mMCAv), mMCAv characteristics (pulsatility index (PI), resistance index (RI)) and hemodynamic variables were measured before, immediately post and 30‐minute post exericse.ResultsBaseline hemodynamics, systolic blood pressure (BP), diastolic BP, mean arterial pressure (MAP), heart rate (HR) and mMCAv were not different between the DS and control group (p>0.05 for all). Neither group showed changes in mMCAv after moderate intensity treadmill walking exercise (p>0.05). However, the DS group exhibited significantly higher PI and RI at all time points when compared to controls (p<0.05 for both).ConclusionsOur results demonstrate that CBF was not altered in individuals with DS at rest and following moderate intensity exercise and was not different from that of controls. However, higher PI and RI in DS group may be associated with reduced distal cerebral perfusion and microvascular damage in individuals with DS. DS (N = 19) Control (N = 19) Baseline Immediate post EX 30‐minute post EX Baseline Immediate post EX 30‐minute post EX SBP (mmHg) 122±14 126±11* 121±13 120±10 130±12* 121±11 DBP (mmHg) 69±9 75±8* 70±9 72±6 81±8* 74±9 MAP (mmHg) 93±10 98±8* 94±9 94±7 103±7* 96±8 mMCAv (cm/s) 64.3±14.9 62.8±13.9 60.8±14.6 69.4±13.1 69.8±14.8 69.6±14.1 PI‡ 0.97±0.14 1.04±0.19 1.02±0.14 0.87±0.12 0.89±0.15 0.86±0.14 RI‡ 0.60±0.05 0.61±0.06 0.61±0.05 0.56±0.05 0.56±0.05 0.55±0.05 Significant group difference, Significant time difference from the baseline. Mean ± SD, Significance level, p < 0.05 This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.