Longitudinal magnetic resonance spectroscopy as marker of cognitive deterioration in mild cognitive impairment.
OBJECTIVE
Amnestic mild cognitive impairment (MCI) is highly predictive of Alzheimer's disease but the pace of deterioration varies across patients. We hypothesize that magnetic resonance spectroscopy (MRS) could be a useful surrogate marker to monitor progression of cognitive impairment in patients with amnestic MCI.


METHODS
A cohort of patients with amnestic MCI underwent single-voxel (1)H-MRS at baseline and at 2-year follow-up. We included 16 patients who converted to dementia of Alzheimer type and other 16 who did not. Changes in cognitive function were compared with the changes in the metabolite levels assessed in vivo.


RESULTS
At baseline the converters had lower mean N-acetyl-aspartate (NAA)/creatine (Cr) ratios in the posteromedial parietal cortex (1.41) than nonconverters (1.47). Most patients tended to lose points in the Mini-Mental test after 2-year follow-up in parallel with decreases in NAA levels (r = .53; P = .002) in the posteromedial parietal cortex as well. The converters showed significant decreases in NAA levels and Cr ratios, whereas the nonconverters did not (P = .001 and .02, respectively) in this area.


CONCLUSIONS
We conclude that MRS is a technique sensitive enough to monitor cognitive changes and progression to dementia in patients with amnestic MCI.
Department of Neurology, Hospital Miguel Servet, Zaragoza, Spain. med009626@saludalia.com
Pedro J
PJ
Modrego
Nicolás
N
Fayed
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D060825:Cognitive Dysfunction / Q000175:diagnosis*; D003401:Creatine / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged
D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine