Hippocampal volumes, proton magnetic resonance spectroscopy metabolites, and cerebrovascular disease in mild cognitive impairment subtypes.
BACKGROUND
Although a majority of patients with amnestic mild cognitive impairment (aMCI) progress to Alzheimer disease, the natural history of nonamnestic MCI (naMCI) is less clear. Noninvasive imaging surrogates for underlying pathological findings in MCI would be clinically useful for identifying patients who may benefit from disease-specific treatments at the prodromal stage of dementia.


OBJECTIVE
To determine the characteristic magnetic resonance imaging (MRI) and proton MR spectroscopy (1H MRS) profiles of MCI subtypes.


METHODS
Case-control study.


METHODS
Community-based sample at a tertiary referral center.


METHODS
Ninety-one patients with single-domain aMCI, 32 patients with multiple-domain aMCI, 20 patients with single- or multiple-domain naMCI, and 100 cognitively normal elderly subjects frequency-matched by age and sex.


METHODS
Posterior cingulate gyrus 1H MRS metabolite ratios, hippocampal volumes, and cerebrovascular disease on MRI.


RESULTS
Patients with single-domain aMCI were characterized by small hippocampal volumes and elevated ratios of myo-inositol to creatine levels. Patients with naMCI on average had normal hippocampal volumes and 1H MRS metabolite ratios, but a greater proportion (3 of 20 patients [15%]) had cortical infarctions compared with patients with single-domain aMCI (6 of 91 [7%]). For characterization of MCI subtypes, 1H MRS and structural MRI findings were complementary.


CONCLUSIONS
The MRI and 1H MRS findings in single-domain aMCI are consistent with a pattern similar to that of Alzheimer disease. Absence of this pattern on average in patients with naMCI suggests that cerebrovascular disease and other neurodegenerative diseases may be contributing to the cognitive impairment in many individuals with naMCI.
Kantarci
Kejal
K
Department of Diagnostic Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA. kantarci.kejal@mayo.edu
Petersen
Ronald C
RC
Przybelski
Scott A
SA
Weigand
Stephen D
SD
Shiung
Maria M
MM
Whitwell
Jennifer L
JL
Negash
Selamawit
S
Ivnik
Robert J
RJ
Boeve
Bradley F
BF
Knopman
David S
DS
Smith
Glenn E
GE
Jack
Clifford R
CR
D000368:Aged; D000369:Aged, 80 and over; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D016022:Case-Control Studies; D002561:Cerebrovascular Disorders / Q000150:complications* / Q000473:pathology*; D016009:Chi-Square Distribution; D002794:Choline / Q000378:metabolism; D003072:Cognition Disorders / Q000145:classification / Q000150:complications*; D015331:Cohort Studies; D003401:Creatine / Q000378:metabolism; D005260:Female; D006624:Hippocampus / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D016013:Likelihood Functions; D008279:Magnetic Resonance Imaging / Q000379:methods; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009483:Neuropsychological Tests; D011522:Protons
D011522:Protons; D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline