Is the eye a window to the mind? Retinal vascular reactivity as a marker for endothelial function in Alzheimer’s disease

<jats:title>Abstract</jats:title><jats:p> <jats:bold>Purpose</jats:bold> To assess the retinal and systemic vascular function in patients diagnosed with mild Alzheimer’s disease in comparison to healthy age matched controls</jats:p><jats:p> <jats:bold>Methods</jats:bold> Nine newly diagnosed mild AD patients (MMSE score 18‐ 24) and 23 healthy age‐matched controls without any cognitive dysfunction (ACE‐R score ≥ 88) were recruited for the study. Retinal vessel reactivity was assessed using the retinal vessel analyser (RVA, IMEDOS, Germany). From these recordings the time taken to reach maximum dilation (RT), was determined for each individual flicker cycle. Systemic vascular function was assessed using flow mediated dilation (FMD) technique at the brachial artery level (Siemens; Acuson Sequoia, UK). Intraocular pressure (IOP) and systemic blood pressure (BP) were also recorded for each participant and OPP was then calculated</jats:p><jats:p> <jats:bold>Results</jats:bold> There were no significant differences in age, mean BP, IOP or OPP between the two study groups (p&gt;0.05). The retinal arterial RT to flicker light stimulation was found to be significantly longer in AD patients as compared to healthy control for both the first (p= 0.01) and the third (p=0.049) flicker cycles. In addition, the RT measured at the chosen vein level was significantly longer in AD patients compared to controls for the first (p=0.046) and second (p=0.043) flicker cycles. No significant differences were found in the brachial arterial diameter between the two groups (p&gt;0.05).</jats:p><jats:p> <jats:bold>Conclusion</jats:bold> In patients suffering from AD, the prolonged retinal vessel RT to flicker provocation could represent an early sign of vascular dysfunction evident at the microvascular level</jats:p>