Blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB) dysfunction are increasingly recognised as pathological hallmarks of vascular dementia and Alzheimer’s disease. Chronic hypertension increases the risk of developing both types of dementia, and may contribute by disrupting the function of blood-brain interfaces. Here we study the permeability of blood-brain and blood-CSF barriers to water using our recently developed multi-flip angle multi-echo (MFAME)-MRI protocol in spontaneously hypertensive rats (SHR). SHRs display increased BBB permeability surface area product to water, relative to age matched controls. Such changes may alter brain water and ion balance and/or contribute to glymphatic dysfunction. Blood-CSF barriers were unaffected.