BACKGROUND: Pathologic change in Alzheimer disease (AD) begins some years before symptoms. MRS has the potential to detect metabolic abnormalities reflecting this early pathologic change. Presenilin 1 (PS1) and amyloid precursor protein (APP) mutation carriers have a nearly 100% risk of developing AD and may be studied prior to symptom onset. METHODS: Short echo time proton MR spectra were acquired from a midline posterior cingulate voxel in presymptomatic carriers of PS1 or APP mutations ("presymptomatic mutation carriers" [PMCs]; n = 7) and age- and sex-matched control subjects (n = 6). Ratios of N-acetyl aspartate (NAA), myo-inositol (MI), and choline-containing compounds (Cho) to creatine (Cr) were measured and NAA/MI calculated. Regression analyses and t tests were performed after log transformation. RESULTS: PMC and control subjects were matched for age and sex. PMC subjects were 1.7 to 21.6 years (mean 9.8 years) before expected symptom onset, predicted from family-specific mean age at onset. Age did not significantly affect metabolite ratios. Geometric mean ratios in control subjects were as follows: NAA/Cr = 1.75, MI/Cr = 0.59, and NAA/MI = 2.95. NAA/Cr and NAA/MI were significantly reduced in PMC relative to controls (NAA/Cr mean decrease 10% [95% CI 2 to 18%]; NAA/MI mean decrease 25% [95% CI 3 to 44%]). MI/Cr was increased in PMC, but the differences did not achieve significance (19% increase [95% CI 1% decrease to 41% increase]; p = 0.07)). In PMCs, reduction in NAA/MI (p = 0.001) and MI/Cr (p = 0.002) were related to proximity of expected age at onset. CONCLUSIONS: Metabolic changes are detectable in presymptomatic mutation carriers years before expected onset of Alzheimer disease. Their magnitude is related to proximity of expected age at onset.
BACKGROUND: Pathologic change in Alzheimer disease (AD) begins some years before symptoms. MRS has the potential to detect metabolic abnormalities reflecting this early pathologic change. Presenilin 1 (PS1) and amyloid precursor protein (APP) mutation carriers have a nearly 100% risk of developing AD and may be studied prior to symptom onset. METHODS: Short echo time proton MR spectra were acquired from a midline posterior cingulate voxel in presymptomatic carriers of PS1 or APP mutations ("presymptomatic mutation carriers" [PMCs]; n = 7) and age- and sex-matched control subjects (n = 6). Ratios of N-acetyl aspartate (NAA), myo-inositol (MI), and choline-containing compounds (Cho) to creatine (Cr) were measured and NAA/MI calculated. Regression analyses and t tests were performed after log transformation. RESULTS: PMC and control subjects were matched for age and sex. PMC subjects were 1.7 to 21.6 years (mean 9.8 years) before expected symptom onset, predicted from family-specific mean age at onset. Age did not significantly affect metabolite ratios. Geometric mean ratios in control subjects were as follows: NAA/Cr = 1.75, MI/Cr = 0.59, and NAA/MI = 2.95. NAA/Cr and NAA/MI were significantly reduced in PMC relative to controls (NAA/Cr mean decrease 10% [95% CI 2 to 18%]; NAA/MI mean decrease 25% [95% CI 3 to 44%]). MI/Cr was increased in PMC, but the differences did not achieve significance (19% increase [95% CI 1% decrease to 41% increase]; p = 0.07)). In PMCs, reduction in NAA/MI (p = 0.001) and MI/Cr (p = 0.002) were related to proximity of expected age at onset. CONCLUSIONS: Metabolic changes are detectable in presymptomatic mutation carriers years before expected onset of Alzheimer disease. Their magnitude is related to proximity of expected age at onset.
Authors: H Randall Griffith; Ozioma C Okonkwo; Jan A den Hollander; Katherine Belue; Jacqueline Copeland; Lindy E Harrell; John C Brockington; David G Clark; Daniel C Marson Journal: Neuropsychol Dev Cogn B Aging Neuropsychol Cogn Date: 2010-04-06
Authors: Eric M McDade; Bradley F Boeve; Julie A Fields; Neeraj Kumar; Rosa Rademakers; Matt C Baker; Bsc David S Knopman; Ronald C Petersen; Clifford R Jack; Kejal Kantarci Journal: J Neuroimaging Date: 2012-05-21 Impact factor: 2.486
Authors: John R Moffett; Brian Ross; Peethambaran Arun; Chikkathur N Madhavarao; Aryan M A Namboodiri Journal: Prog Neurobiol Date: 2007-01-05 Impact factor: 11.685