title: In vivo proton magnetic resonance spectroscopy of the temporal lobe in Alzheimer's disease.
abstract: 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.
authors.affiliation: McLean Hospital Brain Imaging Center, Belmont, MA, USA.
authors.forename: Blaise D
authors.initials: BD
authors.lastname: Frederick
authors.forename: In Kyoon
authors.initials: IK
authors.lastname: Lyoo
authors.forename: Andrew
authors.initials: A
authors.lastname: Satlin
authors.forename: Kyung Heup
authors.initials: KH
authors.lastname: Ahn
authors.forename: Minue J
authors.initials: MJ
authors.lastname: Kim
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Yurgelun-Todd
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Cohen
authors.forename: Perry F
authors.initials: PF
authors.lastname: Renshaw
mesh_terms: 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
chemical_list: D011522:Protons; D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline