Selective reduction of N-acetylaspartate in medial temporal and parietal lobes in AD.
BACKGROUND
Both AD and normal aging cause brain atrophy, limiting the ability of MRI to distinguish between AD and age-related brain tissue loss. MRS imaging (MRSI) measures the neuronal marker N-acetylaspartate (NAA), which could help assess brain change in AD and aging.


OBJECTIVE
To determine the effects of AD on concentrations of NAA, and choline- and creatine-containing compounds in different brain regions and to assess the extent NAA in combination with volume measurements by MRI improves discrimination between AD patients and cognitively normal subjects.


METHODS
Fifty-six patients with AD (mean age: 75.6 +/- 8.0 years) and 54 cognitively normal subjects (mean age: 74.3 +/- 8.1 years) were studied using MRSI and MRI.


RESULTS
NAA concentration was less in patients with AD compared with healthy subjects by 21% (p < 0.0001) in the medial temporal lobe and by 13% to 18% (p < 0.003) in parietal lobe gray matter (GM), but was not changed significantly in white matter and frontal lobe GM. In addition to lower NAA, AD patients had 29% smaller hippocampi and 11% less cortical GM than healthy subjects. Classification of AD and healthy subjects increased significantly from 89% accuracy using hippocampal volume alone to 95% accuracy using hippocampal volume and NAA together.


CONCLUSIONS
In addition to brain atrophy, NAA reductions occur in regions that are predominantly impacted by AD pathology.
Schuff
N
N
Magnetic Resonance Unit, DVA Medical Center San Francisco, CA 94121, USA. nschuff@itsa.ucsf.edu
Capizzano
A A
AA
Du
A T
AT
Amend
D L
DL
O'Neill
J
J
Norman
D
D
Kramer
J
J
Jagust
W
W
Miller
B
B
Wolkowitz
O M
OM
Yaffe
K
K
Weiner
M W
MW
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000378:metabolism* / Q000473:pathology; D000704:Analysis of Variance; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism*; D001284:Atrophy; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D010296:Parietal Lobe / Q000378:metabolism* / Q000473:pathology; D013702:Temporal Lobe / Q000378:metabolism* / Q000473:pathology
D001224:Aspartic Acid; C000179:N-acetylaspartate