Changes in Default Mode Network Connectivity in Resting-State fMRI in People with Mild Dementia Receiving Cognitive Stimulation Therapy.

Tianyin Liu,Daniel C Mograbi,Gloria H Y Wong,Aimee Spector,Gary Cheung

doi:10.3390/brainsci11091137

Abstract

Group cognitive stimulation therapy (CST) is a 7-week activity-based non-pharmacological intervention for people with mild to moderate dementia. Despite consistent evidence of clinical efficacy, the cognitive and brain mechanisms of CST remain unclear. Theoretically, group CST as a person-centred approach may work through promoting social interaction and personhood, executive function, and language use, especially in people with higher brain/cognitive reserve. To explore these putative mechanisms, structural MRI and resting-state functional MRI data were collected from 16 people with mild dementia before and after receiving CST, and in 13 dementia controls who received treatment as usual (TAU). Voxel-based morphometry (VBM) and resting-state functional connectivity (rs-FC) analyses were performed. Compared with TAU, the CST group maintained the total brain volume/total intracranial volume (TBV/TICV) ratio. Increased rs-FC in the default mode network (DMN) in the posterior cingulate cortex and bilateral parietal cortices nodes was observed in the CST over TAU groups between pre- and post-intervention timepoints. We provided preliminary evidence that CST maintains/enhances brain reserve both structurally and functionally. Considering the role of DMN in episodic memory retrieval and mental self-representation, preservation of personhood may be an important mechanism of CST for further investigation.

Highlights

Dementia, including Alzheimer’s disease, vascular dementia, frontotemporal dementia, Lewy body disease, mixed dementia, and other subtypes, affects 50 million people worldwide [1]
This study aims to explore changes in the default mode network (DMN), central executive network (CEN), language network (LAN) during resting state associated as putative brain networks implicated in cognitive stimulation therapy (CST), in the context of individual differences in baseline and change in cognitive reserve among people with mild dementia
The CST group had significantly fewer people with any formal education, both groups had a low level of education, which is common among the current cohort of older persons in Hong Kong due to historical reasons

Summary

Introduction

Dementia, including Alzheimer’s disease, vascular dementia, frontotemporal dementia, Lewy body disease, mixed dementia, and other subtypes, affects 50 million people worldwide [1]. Apart from symptomatic pharmacological treatments, non-pharmacological interventions for dementia are being actively researched to contain this rapidly increasing global disease burden due to population ageing. Group-based cognitive stimulation therapy (CST) is currently the only manualised non-pharmacological intervention recommended in clinical guidelines for people with mild to moderate dementia to promote cognition and quality of life [3], in view of its effectiveness in delaying cognitive decline and improving quality of life with evidence from meta-analyses, with an effect size for cognitive outcome comparable to anti-dementia medication treatment [4,5]. Based on the biopsychosocial model [7], CST emphasises personcentred care, with principles including using reminiscence as an aid to the here-and-stimulating language, and stimulating executive function delivered through a range of activities such as sharing on one’s childhood, word games, and categorising objects [6]

Objectives

Results

Conclusion