The apparent diffusion coefficient (ADC) in brain tissue slightly varies over the cardiac cycle. In this study, we investigate to what extent ADC variations can be explained by brain tissue strain, which affects the measured MRI signals. To this end, we developed a high-field MRI sequence that simultaneously measures both ADC and tissue strain. Preliminary results in 2 volunteers show that ADC fluctuations over the cardiac cycle are an order of magnitude larger than could be explained from measurement errors induced by tissue strains. Consequently, ADC fluctuations in the brain probably reflect physiology.