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Abstract
Background and Objective This was a multicenter study aimed at investigating the characteristics of cognitive decline, neuropsychiatric symptoms, and brain imaging in individuals with subjective cognitive decline (SCD) and subtle cognitive decline (pre–mild cognitive impairment [pre–MCI]).
Methods Data were obtained from the Network-AD project (NET-2011-02346784). The included participants underwent baseline cognitive and neurobehavioral evaluation, FDG-PET, and amyloid PET. We used principal component analysis (PCA) to identify independent neuropsychological and neuropsychiatric dimensions and their association with brain metabolism.
Results A total of 105 participants (SCD = 49, pre–MCI = 56) were included. FDG-PET was normal in 45% of participants and revealed brain hypometabolism in 55%, with a frontal-like pattern as the most frequent finding (28%). Neuropsychiatric symptoms emerging from the Neuropsychiatric Inventory and the Starkstein Apathy Scale were highly prevalent in the whole sample (78%). An abnormal amyloid load was detected in the 18% of the participants who underwent amyloid PET (n = 60). PCA resulted in 3 neuropsychological factors: (1) executive/visuomotor, correlating with hypometabolism in frontal and occipital cortices and basal ganglia; (2) memory, correlating with hypometabolism in temporoparietal regions; and (3) visuospatial/constructional, correlating with hypometabolism in frontoparietal cortices. Two factors emerged from the neuropsychiatric PCA: (1) affective, correlating with hypometabolism in orbitofrontal and cingulate cortex and insula; (2) hyperactive/psychotic, correlating with hypometabolism in frontal, temporal, and parietal regions.
Discussion FDG-PET evidence suggests either normal brain function or different patterns of brain hypometabolism in SCD and pre–MCI. These results indicate that SCD and pre–MCI represent heterogeneous populations. Different neuropsychological and neuropsychiatric profiles emerged, which correlated with neuronal dysfunction in specific brain regions. Long-term follow-up studies are needed to assess the risk of progression to dementia in these conditions.
Glossary
- AAL=
- automated anatomical labeling;
- Aβ=
- β-amyloid;
- AD=
- Alzheimer disease;
- ADL=
- activities of daily living;
- ANOVA=
- analysis of variance;
- CDR=
- Clinical Dementia Rating;
- DLB=
- dementia with Lewy bodies;
- DSM-5=
- Diagnostic and Statistical Manual of Mental Disorders, 5th edition;
- FCSRT=
- Free and Cued Selective Reminding Test;
- KMO=
- Kaiser-Meyer-Olkin;
- MCI=
- mild cognitive impairment;
- MMSE=
- Mini-Mental State Examination;
- NPI=
- Neuropsychiatric Inventory;
- NPS=
- neuropsychiatric symptoms;
- PCA=
- principal component analysis;
- pre–MCI=
- pre–mild cognitive impairment;
- ROI=
- region of interest;
- SAS=
- Starkstein Apathy Scale;
- SCD=
- subjective cognitive decline;
- SPM=
- statistical parametric mapping;
- SUVR=
- standard uptake value ratio;
- TMT=
- Trail-Making Test
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Submitted and externally peer reviewed. The handling editor was Linda Hershey, MD, PhD.
- Received September 4, 2021.
- Accepted in final form February 21, 2022.
- © 2022 American Academy of Neurology
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