Background: Longitudinal changes of brain metabolites during a functional stimulation
are unknown in amnestic mild cognitive impairment (aMCI) and Alzheimer’s disease (AD) subjects.
Objective: This study was to evaluate the longitudinal changes of brain metabolites using proton
magnetic resonance spectroscopy (1H MRS) in response to treatment during a memory task in the
subjects of cognitive normal (CN), aMCI, and AD.
Methods: We acquired functional magnetic resonance spectroscopy (fMRS) data from 28 CN elderly,
16 aMCI and 12 AD subjects during a face-name association task. We measured fMRS metabolite
ratios over 24 months in the 8-month apart, determined the temporal changes of the metabolites,
and evaluated the differences among the three groups under the three different conditions
(base, novel, repeat).
Results: The results of comparisons for the three subject groups and the three-time points showed
that tNAA/tCho and tCr/tCho were statistically significant among the three subject groups in any
of the three conditions. The dynamic temporal change measurements for the metabolites for each
condition showed that Glx/tCho and Glu/tCho levels at the third visit increased significantly compared
with in the first visit in the novel condition in the AD group.
Conclusion: We found declines in tNAA/tCho and tCr/tCho in the aMCI and AD subjects with increasing
disease severity, being highest in CN and lowest in AD. The Glx/tCho level increased temporally
in the AD subjects after they took an acetylcholine esterase inhibitor. Therefore, Glx may
be suitable to demonstrate functional recovery after treatment.