Post-prandial hyperlipidaemia impairs systemic vascular function and dynamic cerebral autoregulation in young and old male adults

<h2>Abstract</h2> To what extent post-prandial hyperlipidaemia (PPH) impacts both systemic vascular function and dynamic cerebral autoregulation (dCA) is unknown. To address this, we recruited 20 healthy young males (24 + 5 y) and compared them to 21 healthy older males (67 + 6 y). In both groups, the following measurements were performed: systemic vascular function was assessed via flow-mediated dilation (FMD) using duplex ultrasound. Forced oscillations in mean arterial pressure (squat-stand manoeuvres) were used to assess dCA via transfer function analysis, with middle cerebral artery velocity recorded continuously. Venous samples were assayed for triglycerides, glucose and insulin. All measurements were completed following an overnight fast prior to and 4 hours following consumption of a standardised high-fat meal. Older males exhibited comparable basal FMD (<i>P</i> = 0.635 <i>vs.</i> young) and dCA (<i>P</i> = 0.170-0.998), whereas cerebral perfusion was lower (<i>P</i> = <0.001-0.028). Triglycerides (<i>P</i> = < 0.001), glucose (<i>P</i> = 0.011) and insulin (<i>P</i> = < 0.001) increased in both groups post-prandially, resulting in impaired FMD (<i>P</i> = 0.032), increased cerebral pulsatility (<i>P</i> = < 0.001) and reduced dCA (<i>P</i> = 0.007-0.037), with the latter more marked in older participants. These findings are the first to demonstrate PPH impairs both systemic vascular function and dCA in both young and old male adults, with the older brain at greater risk.