Data from: Brain myo-inositol as a potential marker of amyloid-related pathology: a longitudinal study.

Objective: To investigate the association between longitudinal changes in
proton magnetic spectroscopy (MRS) metabolites and amyloid pathology in
non-demented individuals; to explore the relationship between MRS and
cognitive decline. Methods: In this longitudinal multiple time point study
(a subset of the Swedish BioFINDER) we included cognitively healthy
participants, individuals with subjective cognitive decline and mild
cognitive impairment (MCI). MRS was acquired serially in 294 participants
(670 individual spectra) from the posterior cingulate/precuneus. Using
mixed-effects models, we assessed the association between MRS and baseline
amyloid β42 (Aβ), and between MRS and longitudinal MMSE, accounting for
APOE, age and sex. Results: While baseline MRS metabolites were similar in
Aβ positive (Aβ+) and negative (Aβ-) individuals, in the Aβ+ group, the
estimated rate of change was +1.9%/year for myo-inositol/creatine (mI/Cr)
and -2.0%/year for N-acetyl-aspartate/myo-inositol (NAA/mI). In the Aβ-
group, mI/Cr and NAA/mI yearly change was -0.05% and +1.2%, however this
was not significant across time points. MCI Aβ+ group showed the steepest
MRS changes, with an estimated rate of +2.93%/year (p=0.07) for mI/Cr and
-3.55%/year (p<0.01) for NAA/mI. Further, in the entire cohort, we
found that Aβ+ individuals with low baseline NAA/mI had a significantly
higher rate of cognitive decline than Aβ+ individuals with high baseline
NAA/mI. Conclusions: We demonstrate that the longitudinal change in mI/Cr
and NAA/mI is associated with underlying amyloid pathology. MRS may be a
useful non-invasive marker of Aβ-related processes over time. Further, we
show that in Aβ+ individuals, baseline NAA/mI may predict the rate of
future cognitive decline.