Shortening of hippocampal spin-spin relaxation time in probable Alzheimer's disease: a 1H magnetic resonance spectroscopy study.

We quantified the differential effects of the spin-spin relaxation times (T2) of tissue water and cerebral spinal fluid in order to examine hippocampal T2 changes as a non-invasive bio-marker of Alzheimer's disease (AD). We measured T2 in the right hippocampus of ten patients fulfilling the NINCDS-ADRDA criteria for AD and 40 healthy adult volunteers using localized proton magnetic resonance spectroscopy. The T2 values of AD patients (73 +/- 8 ms) were significantly shorter (P < 0.01) than those of healthy age-matched controls (81 +/- 5 ms), and there was a reduction in T2 for healthy older vs. healthy younger adults (87 +/- 5 ms, P < 0.05). The reduced T2 values with aging are consistent with age-related decreases in tissue water content. Our results suggest that there may be a severe reduction in tissue water content in AD.