title: A longitudinal study of magnetic resonance spectroscopy Huntington's disease biomarkers.
abstract: Putaminal metabolites examined using cross-sectional magnetic resonance spectroscopy (MRS) can distinguish pre-manifest and early Huntington's Disease (HD) individuals from controls. An ideal biomarker, however, will demonstrate longitudinal change over short durations. The objective here was to evaluate longitudinal in vivo brain metabolite profiles in HD over 24 months. Eighty-four participants (30 controls, 25 pre-manifest HD, 29 early HD) recruited as part of TRACK-HD were imaged at baseline, 12 months, and 24 months using 3T MRS of left putamen. Automated putaminal volume measurement was performed simultaneously. To quantify partial volume effects, spectroscopy was performed in a second, white matter voxel adjacent to putamen in six subjects. Subjects underwent TRACK-HD motor assessment. Statistical analyses included linear regression and one-way analysis of variance (ANOVA). At all time-points N-acetyl aspartate and total N-acetyl aspartate (NAA), neuronal integrity markers, were lower in early HD than in controls. Total NAA was lower in pre-manifest HD than in controls, whereas the gliosis marker myo-inositol (MI) was robustly elevated in early HD. Metabolites were stable over 24 months with no longitudinal change. Total NAA was not markedly different in adjacent white matter than putamen, arguing against partial volume confounding effects in cross-sectional group differences. Total NAA correlations with disease burden score suggest that this metabolite may be useful in identifying neurochemical responses to therapeutic agents. We demonstrate almost consistent group differences in putaminal metabolites in HD-affected individuals compared with controls over 24 months. Future work establishing spectroscopy as an HD biomarker should include multi-site assessments in large, pathologically diverse cohorts.
authors.affiliation: Centre for Molecular Medicine & Therapeutics, Vancouver, Canada; Centre for Huntington Disease, University of British Columbia (UBC) Hospital, Vancouver, Canada.
authors.forename: Aaron
authors.initials: A
authors.lastname: Sturrock
authors.forename: Corree
authors.initials: C
authors.lastname: Laule
authors.forename: Katy
authors.initials: K
authors.lastname: Wyper
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Milner
authors.forename: Joji
authors.initials: J
authors.lastname: Decolongon
authors.forename: Rachelle
authors.initials: R
authors.lastname: Dar Santos
authors.forename: Allison J
authors.initials: AJ
authors.lastname: Coleman
authors.forename: Kimberley
authors.initials: K
authors.lastname: Carter
authors.forename: Susan
authors.initials: S
authors.lastname: Creighton
authors.forename: Natalie
authors.initials: N
authors.lastname: Bechtel
authors.forename: Stefan
authors.initials: S
authors.lastname: Bohlen
authors.forename: Ralf
authors.initials: R
authors.lastname: Reilmann
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Johnson
authors.forename: Michael R
authors.initials: MR
authors.lastname: Hayden
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Tabrizi
authors.forename: Alex L
authors.initials: AL
authors.lastname: Mackay
authors.forename: Blair R
authors.initials: BR
authors.lastname: Leavitt
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006816:Huntington Disease / Q000378:metabolism* / Q000473:pathology*; D007294:Inositol / Q000378:metabolism; D008137:Longitudinal Studies; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D011699:Putamen / Q000473:pathology; D013223:Statistics as Topic; D013997:Time Factors; D066127:White Matter / Q000473:pathology
chemical_list: D015415:Biomarkers; D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate
keywords: Huntington's disease; MRI; MRS; N-acetyl aspartate (NAA); myo-inositol (MI)