Cerebral Blood Flow Abnormalities in Down Syndrome Regression Disorder.

This study aimed to examine cerebral blood flow velocity (CBFV) in the middle cerebral artery (MCA) and internal carotid artery (ICA) of individuals with Down syndrome (DS) and Down Syndrome Regression Disorder (DSRD). A single-center, prospective observational study was performed to evaluate CBFV in individuals with DS and DSRD using transcranial Doppler (TCD) ultrasound. Individuals with DS without regression and DSRD were recruited in a 1:1 manner. TCD studies were performed using a standardized protocol for children. In total, 104 individuals were enrolled, with 60 (57.7%) having DSRD and 44 (42.3%) having DS only. Individuals with DSRD had lower average MCA values (mean difference: -6.89, 95% confidence interval [CI]: -12.88, -0.90; P = 0.024) and ICA values (-4.98, 95% CI: -9.58, -0.38; P = 0.034) when compared with individuals with DS only. These differences were more apparent in the left MCA (-8.97, 95% CI: -15.89, -2.06; P = 0.011) and left ICA (-5.65, 95% CI: -11.11, -0.19; P = 0.042). Age, hemodynamic measures, and neuropsychiatric disease severity did not modify the differences in MCA and ICA between patients with DSRD and DS. However, in patients with DSRD, MCA values decreased on average by -0.40 (95% CI: -0.78, -0.02; P = 0.038) for every unit increase in heart rate compared with patients with DS. This study revealed CBFV alterations in individuals with DSRD when compared with DS alone, demonstrating reduced CBFV in both the MCA and ICA. These findings suggest disrupted cerebral autoregulation, potentially driven by the presence of catatonia in individuals with DSRD.