Background:
Mild cognitive impairment (MCI) is a state between normal cognition and
dementia. However, MCI diagnosis does not necessarily guarantee the progression to dementia.
Since no previous study investigated brain positron emission tomography (PET) imaging of MCI--
to-normal reversion, we provided PET imaging of MCI-to-normal reversion using the Alzheimer's
Disease Neuroimaging Initiative (ADNI) database.
Methods:
We applied comprehensive neuropsychological criteria (NP criteria), consisting of mem-
ory, language, and attention/executive function domains, to include patients with a baseline diagno-
sis of MCI (n=613). According to the criteria, the year 1 status of the patients was categorized into
three groups (reversion: n=105, stable MCI: n=422, conversion: n=86). Demographic, neuropsycho-
logical, genetic, CSF, and cognition biomarker variables were compared between the groups. Addi-
tionally, after adjustment for confounding variables, the deposition pattern of amyloid-β and cere-
bral glucose metabolism were compared between three groups via AV45- and FDG-PET modali-
ties, respectively.
Results:
MCI reversion rate was 17.1% during one year of follow-up. The reversion group had the
lowest frequency of APOE ε4+ subjects, the highest CSF level of amyloid-β, and the lowest CSF
levels of t-tau and p-tau. Neuropsychological assessments were also suggestive of better cognitive
performance in the reversion group. Patients with reversion to normal state had higher glucose
metabolism in bilateral angular and left middle/inferior temporal gyri, when compared to those
with stable MCI state. Meanwhile, lower amyloid-β deposition at baseline was observed in the fron-
tal and parietal regions of the reverted subjects. On the other hand, the conversion group showed
lower cerebral glucose metabolism in bilateral angular and bilateral middle/inferior temporal gyri
compared to the stable MCI group, whereas the amyloid-β accumulation was similar between the
groups.
Conclusions:
This longitudinal study provides novel insight regarding the application of PET imag-
ing in predicting MCI transition over time.
Mild cognitive impairment and fMRI studies of brain functional connectivity: the state of the art
