Early Changes in Alpha Band Power and DMN BOLD Activity in Alzheimer's Disease: A Simultaneous Resting State EEG-fMRI Study.

Simultaneous resting state functional magnetic resonance imaging (rsfMRI)-resting state electroencephalography (rsEEG) studies in healthy adults showed robust positive associations of signal power in the alpha band with BOLD signal in the thalamus, and more heterogeneous associations in cortical default mode network (DMN) regions. Negative associations were found in occipital regions. In Alzheimer's disease (AD), rsfMRI studies revealed a disruption of the DMN, while rsEEG studies consistently reported a reduced power within the alpha band. The present study is the first to employ simultaneous rsfMRI-rsEEG in an AD sample, investigating the association of alpha band power and BOLD signal, compared to healthy controls (HC). We hypothesized to find reduced positive associations in DMN regions and reduced negative associations in occipital regions in the AD group. Simultaneous resting state fMRI-EEG was recorded in 14 patients with mild AD and 14 HC, matched for age and gender. Power within the EEG alpha band (8-12 Hz, 8-10 Hz, and 10-12 Hz) was computed from occipital electrodes and served as regressor in voxel-wise linear regression analyses, to assess the association with the BOLD signal. Compared to HC, the AD group showed significantly decreased positive associations between BOLD signal and occipital alpha band power in clusters in the superior, middle and inferior frontal cortex, inferior temporal lobe and thalamus (p < 0.01, uncorr., cluster size ≥ 50 voxels). This group effect was more pronounced in the upper alpha sub-band, compared to the lower alpha sub-band. Notably, we observed a high inter-individual heterogeneity. Negative associations were only reduced in the lower alpha range in the hippocampus, putamen and cerebellum. The present study gives first insights into the relationship of resting-state EEG and fMRI characteristics in an AD sample. The results suggest that positive associations between alpha band power and BOLD signal in numerous regions, including DMN regions, are diminished in AD.

Cognitive Rehabilitation in Alzheimer's Disease: A Controlled Intervention Trial.

BACKGROUND: Cognitive Rehabilitation for Alzheimer's disease (AD) is an integrative multimodal intervention. It aims to maintain autonomy and quality of life by enhancing the patients' abilities to compensate for decreased cognitive functioning. OBJECTIVE: We evaluated the feasibility of a group-based Cognitive Rehabilitation approach in mild AD dementia and assessed its effect on activities of daily living (ADL). METHODS: We included 16 patients with AD dementia in a controlled partial-randomized design. We adapted the manual-guided Cognitive Rehabilitation program (CORDIAL) to a group setting. Over the course of three months, one group received the Cognitive Rehabilitation intervention (n = 8), while the other group received a standardized Cognitive Training as an active control condition (n = 8). ADL-competence was measured as primary outcome. The secondary outcome parameters included cognitive abilities related to daily living, functional cognitive state, and non-cognitive domains, e.g., quality of life. For each scale, we assessed the interaction effect 'intervention by time', i.e., from pre-to post-intervention. RESULTS: We found no significant interaction effect of intervention by time on the primary outcome ADL-competence. The interaction effect was significant for quality of life (Cohen's d: -1.43), showing an increase in the intervention group compared with the control group. CONCLUSIONS: Our study demonstrates the feasibility of a group-based Cognitive Rehabilitation program for patients with mild AD dementia. The Cognitive Rehabilitation showed no significant effect on ADL, possibly reflecting a lack of transfer between the therapy setting and real life. However, the group setting enhanced communication skills and coping mechanisms. Effects on ADL may not have reached statistical significance due to a limited sample size. Furthermore, future studies might use an extended duration of the intervention and integrate caregivers to a greater extent to increase transfer to activities of daily living.

Does Functional Connectivity Provide a Marker for Cognitive Rehabilitation Effects in Alzheimer's Disease? An Interventional Study.

BACKGROUND: Cognitive rehabilitation (CR) is a cognitive intervention for patients with Alzheimer's disease (AD) that aims to maintain everyday competences. The analysis of functional connectivity (FC) in resting-state functional MRI has been used to investigate the effects of cognitive interventions. OBJECTIVES: We evaluated the effect of CR on the default mode network FC in a group of patients with mild AD, compared to an active control group. METHODS: We performed a three-month interventional study including 16 patients with a diagnosis of AD. The intervention group (IG) consisted of eight patients, performing twelve sessions of CR. The active control group (CG) performed a standardized cognitive training. We used a seed region placed in the posterior cingulate cortex (PCC) for FC analysis, comparing scans acquired before and after the intervention. Effects were thresholded at a significance of p < 0.001 (uncorrected) and a minimal cluster size of 50 voxels. RESULTS: The interaction of group by time showed a higher increase of PCC connectivity in IG compared to CG in the bilateral cerebellar cortex. CG revealed widespread, smaller clusters of higher FC increase compared with IG. Across all participants, an increase in quality of life was associated with connectivity increase over time in the bilateral precuneus. CONCLUSIONS: CR showed an effect on the FC of the DMN in the IG. These effects need further study in larger samples to confirm if FC analysis may suit as a surrogate marker for the effect of cognitive interventions in AD.