Table 3 Summary of functional MRI studies
From: Neuroimaging advances regarding subjective cognitive decline in preclinical Alzheimer’s disease
Authors | Definition of SCD | Modality | Design | Sample (mean age ± SD) | Main findings |
|---|---|---|---|---|---|
Dummas et al. (2013) [145] | Endorsed more than 20% of the items on the complaint inventory | Task-fMRI | Cross-sectional | NC: n = 11 (56.8 ± 1.9) SCD: n = 12 (57.1 ± 2.3) | SCD had increased activations in middle frontal gyrus, precuneus and cingulate gyrus compared to NC. |
Erk et al. (2011) [146] | Memory clinic consultation | Task-fMRI | Cross-sectional | NC: n = 20 (66.8 ± 5.4) SCD: n = 19 (68.4 ± 5.7) | SCD was associated with a reduction in right hippocampal activation during episodic memory recall in the absence of performance deficits and increased activation of the right dorsolateral prefrontal cortex. |
Rodda et al. (2009) [147] | Self-perceived memory difficulties persistent and severe enough to seek advice despite normal cognition | Task-fMRI | Cross-sectional | NC: n = 10 (68.0 ± 13.5) SCD: n = 10 (64.2 ± 5.6) | SCD exhibited increased activation in left during the divided attention task. |
Hu et al. (2017) [150] | Criteria by SCD-I | Task-fMRI | Cross-sectional | NC: n = 24 (66.5 ± 7.2) SCD: n = 20 (68.3 ± 7.9) | Subtle neuronal network disruptions in SCD. |
Hayes et al. (2017) [149] | Worrisome decline in memory | Task-fMRI | Cross-sectional | NC: n = 41 (67.5 ± 9.1) SCD: n = 23 (68.6 ± 8.2) | SCD showed a more negative subsequent memory effects in the default mode network. |
Dillen et al. (2017) [138] | A cut-off value of≥25 on the memory complaint questionnaire but average scores on neuropsychological tests | rs-fMRI | Cross-sectional | NC: n = 25 (62.4 ± 7.0) SCD: n = 28 (65.8 ± 7.8) Prodromal AD: n = 25 (70.8 ± 6.2) | SCD showed decreased connectivity between DMN and hippocampus. |
Hafkemeijer et al. (2013) [73] | Memory complaints but normal cognition | T1 MRI and rs-fMRI | Cross-sectional | NC: n = 29 (71.3 ± 3.4) SCD: n = 25 (71.4 ± 9.2) | SMC showed increased FC in the default mode network. |
Sun et al. (2016) [122] | Self-reported persistent decline in memory compared with a previous state but normal cognition | T1 MRI and rs-fMRI | Cross-sectional | NC: n = 61 (64.1 ± 8.6) SCD: n = 25 (65.5 ± 6.1) | SCD had higher ALFF values in the left inferior parietal lobule and right middle occipital gyrus than control subjects, which were correlated with verbal episodic memory scores. |
Verfaillie et al. (2018) [128] | 1 binary question | rs-fMRI | Longitudinal (one year) | Baseline NC: n = 56 (64 ± 5) Baseline SCD: n = 68 (64 ± 5) Follow-up NC: n = 29 (65 ± 6) Follow-up SCD: n = 30 (65 ± 6) | SCD showed increased pDMN–MTMS connectivity. Higher connectivity between MTMS and the rest of brain was associated with better baseline immediate memory, attention, and global cognition. Higher MTMS and pDMN–MTMS connectivity were associated with lower immediate memory over time. |
Wang et al. (2013) [139] | Endorsed more than 20% of the items on the Cognitive Complaint Index | rs-fMRI | Cross-sectional | NC: n = 16 (70.7 ± 6.0) SCD: n = 23 (70.1 ± 7.3) MCI: n = 18 (73.7 ± 9.1) | SCD showed decreased DMN connectivity in the right hippocampus compared to NC and higher connectivity compared to MCI. |
Yasuno et al. (2015) [113] | Reisberg criteria | rs-fMRI | Cross-sectional | NC: n = 30 (72.2 ± 4.8) SCD: n = 23 (69.6 ± 8.0) | SCD showed reduced FC in cortical midline structures |
Cavedo et al. (2018) | subjective memory complaints | 18F-florbetapir-PET FDG-PET MRI | Cross-sectional | Women: n=201 (76.02±3.24) Men: n = 117(76.05±3.85) | Men had lower resting-state FC. |
Chiesa et al., (2019) [140] | 2 binary questions | rs-fMRI | Cross-sectional | ApoE ɛ4+: 44 (75.6 ± 3.5) ApoE ɛ4-: 180 (75.5 ± 3.4) | ApoE ɛ4+ showed slower increase in FC in frontal lobes. |
Dillen et al., (2016) [136] | Structural questionnaire | rs-fMRI | Cross-sectional | NC: n = 25 (62.4 ± 7.0) SCD: n = 27 (65.7 ± 7.9) AD: n = 24 (71.0 ± 6.2) | Higher FC from RSC to frontal cortex in SCD. |
Dong et al., (2018) [137] | Memory clinic consultation | rs-fMRI | Cross-sectional | NC: n = 39 (82.89 ± 4.13) SCD: n = 39 (83 ± 4.43) | Lower aFCS in SCD. |
Viviano et al., (2019) [115] | 2 binary questions | rs-fMRI | Cross-sectional | NC: n = 48 (66.96 ± 8.79) SCD: n = 35 (68.51 ± 7.66) | SCD showed lower average FC. |
Eulate el al., (2017) [163] | Memory clinic consultation | ASL | Cross-sectional | NC: n = 32 (72.3 ± 5.6) SCD: n = 28 (67.3 ± 7.8) MCI: n = 34 (73.7 ± 7.5) AD: n = 21 (75.8 ± 6.2) | No differences in CBF between SCD and HC. |
Hays et al., (2018) [162] | Memory clinic consultation | ASL | Cross-sectional | NC: n = 35 (73 ± 6.25) SCD: n = 35 (72.54 ± 5.07) | SCD showed negative associations between verbal memory and CBF. |
Leeuwis et a., (2017) [164] | Memory clinic consultation | ASL | Cross-sectional | SCD: n = 143 (56.69 ± 8.69) MCI: n = 95 (65.24 ± 7.28) AD: n = 161 (65.93 ± 7.04) | No correlation between CBF and cognition. |
Yang et al., (2019) [165] | SCD-I Working Group | rs-fMRI | Cross-sectional | NC: n = 55 (63.41 ± 7.97) SCD: n = 43 (65.09 ± 8.66) aMCI: n = 52 (68.06 ± 9.32) AD: n = 44 (70.98 ± 10.02) | SCD showed lower fALFF. |