PSEN1 and early-onset autosomal dominant Alzheimer disease: Here, we show, in the amyloid precursor protein / presenilin 1 (APP/PS1) mouse model of Alzheimer’s disease, that diffusion-weighted magnetic resonance spectroscopy (dMRS) in vivo allows capturing variations of the intracellular–extracellular distribution of brain lactate, by exploiting the different diffusion properties in both compartments.