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Neurology. 2016 May 10;86(19):1754-61. doi: 10.1212/WNL.0000000000002672. Epub 2016 Apr 15.

Myo-inositol changes precede amyloid pathology and relate to APOE genotype in Alzheimer disease.

Author information

1
From Clinical Geriatrics (O.V., L.-O.W., E.W.), Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm; Department of Diagnostic Radiology (P.C.S., O.S.), Lund University; Clinical Neurochemistry Laboratory (H.Z., K.B.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; UCL Institute of Neurology (H.Z.), Queen Square, London, UK; Memory Clinic (L.M., O.H.), Skåne University Hospital; and Clinical Memory Research Unit (L.M., O.H.), Department of Clinical Sciences, Malmö, Lund University, Sweden. olga.voevodskaya@ki.se oskar.hansson@med.lu.se.
2
From Clinical Geriatrics (O.V., L.-O.W., E.W.), Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm; Department of Diagnostic Radiology (P.C.S., O.S.), Lund University; Clinical Neurochemistry Laboratory (H.Z., K.B.), Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; UCL Institute of Neurology (H.Z.), Queen Square, London, UK; Memory Clinic (L.M., O.H.), Skåne University Hospital; and Clinical Memory Research Unit (L.M., O.H.), Department of Clinical Sciences, Malmö, Lund University, Sweden.

Abstract

OBJECTIVE:

We aimed to test whether in vivo levels of magnetic resonance spectroscopy (MRS) metabolites myo-inositol (mI), N-acetylaspartate (NAA), and choline are abnormal already during preclinical Alzheimer disease (AD), relating these changes to amyloid or tau pathology, and functional connectivity.

METHODS:

In this cross-sectional multicenter study (a subset of the prospective Swedish BioFINDER study), we included 4 groups, representing the different stages of predementia AD: (1) cognitively healthy elderly with normal CSF β-amyloid 42 (Aβ42), (2) cognitively healthy elderly with abnormal CSF Aβ42, (3) patients with subjective cognitive decline and abnormal CSF Aβ42, (4) patients with mild cognitive decline and abnormal CSF Aβ42 (Ntotal = 352). Spectroscopic markers measured in the posterior cingulate/precuneus were considered alongside known disease biomarkers: CSF Aβ42, phosphorylated tau, total tau, [(18)F]-flutemetamol PET, f-MRI, and the genetic risk factor APOE.

RESULTS:

Amyloid-positive cognitively healthy participants showed a significant increase in mI/creatine and mI/NAA levels compared to amyloid-negative healthy elderly (p < 0.05). In amyloid-positive healthy elderly, mI/creatine and mI/NAA correlated with cortical retention of [(18)F] flutemetamol tracer ([Formula: see text] = 0.44, p = 0.02 and [Formula: see text] = 0.51, p = 0.01, respectively). Healthy elderly APOE ε4 carriers with normal CSF Aβ42 levels had significantly higher mI/creatine levels (p < 0.001) than ε4 noncarriers. Finally, elevated mI/creatine was associated with decreased functional connectivity within the default mode network (rpearson = -0.16, p = 0.02), independently of amyloid pathology.

CONCLUSIONS:

mI levels are elevated already at asymptomatic stages of AD. Moreover, mI/creatine concentrations were increased in healthy APOE ε4 carriers with normal CSF Aβ42 levels, suggesting that mI levels may reveal regional brain consequences of APOE ε4 before detectable amyloid pathology.

PMID:
27164711
PMCID:
PMC4862247
DOI:
10.1212/WNL.0000000000002672
[Indexed for MEDLINE]
Free PMC Article

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