Objectives. Vascular mechanisms underlying brain atrophy and white matter lesions (WML) in patients with type 2 diabetes (T2DM) are unknown. Increased blood pressure (BP) during moderate exercise is associated with end-organ damage and could help explain these brain abnormalities. This study sought to examine associations between exercise central haemodynamics and brain structure.
Methods. Forty healthy controls (53±9 years; 50% male) and 40 T2DM (62±9 years; 50% male) participants were examined at rest and during moderate intensity semi-recumbent cycling. Resting and exercise central haemodynamics, including systolic BP (SBP), pulse pressure (PP) augmented pressure (AP), augmentation index (AIx), aortic stiffness and aortic reservoir function (including excess pressure integral [xsP], which is analogous to aortic flow) were recorded by tonometry. Segmented grey (GM) and white matter (WM) and WML volumes were derived from magnetic resonance imaging.
Results. T2DM participants had lower WM (p=0.004) and a trend towards lower GM (p=0.07). All central hemodynamic variables were significantly elevated in T2DM during exercise (p<0.01 for all). At rest, greater central (not brachial) haemodynamics (SBP, AP, AIx and PP) were independently associated with greater WML volume (standardised β=0.54, p=0.031, β=0.55, p=0.01; β=0.46, p=0.046 and; β=0.48, p=0.01, respectively) in controls, but not in T2DM. During exercise, increased xsP was independently associated with reduced volumes of WM (β =-0.54, p=0.006) and GM (β=-0.63, p=0.013) only in T2DM independent of age, sex, heart rate, and 24-hour ambulatory SBP.
Conclusions. In T2DM, aortic reservoir function and transmission of excess aortic flow during exercise is associated with brain atrophy. These novel findings suggest that vascular mechanisms underlying structural brain changes may differ between healthy individuals and those with T2DM.