In vivo proton magnetic resonance spectroscopy of the temporal lobe in Alzheimer's disease.
OBJECTIVE
Prior proton magnetic resonance spectroscopy (MRS) studies have consistently reported decreased brain n-acetyl aspartate (NAA) levels and increased myo-inositol (mI) levels in subjects with Alzheimer's disease (AD) relative to healthy comparison subjects. These studies have usually been conducted in small and homogeneous populations of patients with established Alzheimer's disease. Few studies have tested the usefulness of this finding in a general population seeking evaluation for memory loss and other cognitive declines. We designed a study to evaluate the significance of single-voxel proton MRS findings in these patients with memory loss and other cognitive declines. GENERAL METHOD: Thirty-five subjects with a primary complaint of memory loss and other cognitive declines were consecutively referred over a period of 13 months to a specialty clinic. Patients with a diagnosis of mild to moderate probable Alzheimer's disease (N = 22), non-Alzheimer's dementia (depression, multiinfarct dementia, Parkinson's Disease, Korsakoff's Psychosis, and bipolar disorder; N = 13), and healthy comparison subjects (N = 18) were examined with respect to possible differences in metabolites using proton MRS in a 3.4-ml anterior temporal lobe voxel.


RESULTS
The Alzheimer's disease group had 10.7% lower NAA/creatine (Cr) ratios relative to the healthy comparison group and 9.4% lower NAA/creatine relative to the non-Alzheimer's dementia group (15.0% lower NAA/creatine relative to the depression subgroup of the non-Alzheimer's dementia group). There were no significant differences in choline (Cho) or myo-inositol ratios among the groups. There were significant correlations between NAA/creatine ratios and mini-mental status exam (MMSE) scores in subjects with Alzheimer's disease (t = 2.41, p = 0.032) but not in subjects with non-Alzheimer's dementia or in its depression subgroup.


CONCLUSIONS
This study found a reduction in the neuronal marker NAA in the anterior temporal lobe of patients diagnosed with probable Alzheimer's disease, using a short add-on proton MRS exam. This change was not observed in patients whose memory loss and other cognitive declines were not attributed to Alzheimer's disease, suggesting that it may aid in the diagnosis or detection of Alzheimer's disease.
Frederick
Blaise D
BD
McLean Hospital Brain Imaging Center, Belmont, MA, USA.
Lyoo
In Kyoon
IK
Satlin
Andrew
A
Ahn
Kyung Heup
KH
Kim
Minue J
MJ
Yurgelun-Todd
Deborah A
DA
Cohen
Bruce M
BM
Renshaw
Perry F
PF
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications / Q000175:diagnosis*; D000704:Analysis of Variance; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001931:Brain Mapping; D016022:Case-Control Studies; D002794:Choline / Q000378:metabolism; D003072:Cognition Disorders / Q000150:complications / Q000175:diagnosis; D003401:Creatine / Q000378:metabolism; D003704:Dementia / Q000175:diagnosis / Q000209:etiology; D005260:Female; D006801:Humans; D007294:Inositol / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis / Q000209:etiology; D008609:Mental Status Schedule; D011522:Protons; D013702:Temporal Lobe / Q000378:metabolism* / Q000473:pathology
D011522:Protons; D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline