Cognitive training reorganize functional lateralization in vascular cognitive impairment no dementia

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Abstract Submission 

Xinhu Jin¹, Yi Xing², Xiuyi Wang¹, Yi Tang², Yi Du¹

¹Chinese Academy of Sciences, Beijing, Beijing, ²Capital Medical University, Beijing, Beijing

Xinhu Jin  
Chinese Academy of Sciences
Beijing, Beijing

Yi Xing  
Capital Medical University
Beijing, Beijing

Xiuyi Wang  
Chinese Academy of Sciences
Beijing, Beijing

Yi Tang  
Capital Medical University
Beijing, Beijing

Yi Du  
Chinese Academy of Sciences
Beijing, Beijing

Vascular cognitive impairment no dementia (VCIND) refers to cognitive deficits associated with an underlying vascular cause but is not sufficient for diagnosing dementia [1]. Early intervention of VCIND holds the potential to delay or even reverse cognitive impairment [2]. Cognitive training refers to a structured intervention where individuals engage in practice activities that target specific cognitive functions, such as executive function and memory. However, the impacts of subcortical VCIND and cognitive training on functional lateralization, an intrinsic organizational principle of human brain, remain unclear.

In a randomized, active controlled design, 30 patients with VCIND underwent a 7-week computerized, adaptive, multidomain training while the other 30 patients received fixed processing speed and attention tasks set to a primary difficulty level. Based on resting-state functional connectivity (FC) processed by fMRIPrep and XCP-D [3,4], we first defined two different types of FC among the whole brain, named interhemispheric heterotopic FC and intrahemispheric FC. For a specific parcel in multimodal parcellation [5], the heterotopic (he) was defined as the sum of heterotopic FCs between this parcel and all the others in the opposite hemisphere except the homotopic one, whereas the intrahemispheric (intra) was defined as the sum of intrahemispheric FCs between this parcel and all the others within the same hemisphere. The resting-state functional lateralization between each homotopic pair of parcels was quantified by a commonly used laterality index (LI) calculated as: LI = (L-R)/|(L+R)|. According to Cole-Anticevic Brain-wide Network Partition version 1.0 (CAB-NP v1.0) [6], all cortical parcels were mapped into 12 networks. Since executive dysfunction is the characteristic impairment in subcortical vascular cognitive impairment [7,8], brain areas within the fronto-parietal network (FPN) may play a crucial role in cognitive training for subcortical VCIND. In order to calculate the LI of FPN, we only chose the homotopic pair of parcels both belonging to FPN in CAB-NP v1.0. After averaging the LIs across these pairs of FPN parcels, we acquired the LI_he/LI_intra of FPN for each participant. Larger positive values of LI_he and LI_intra imply stronger bilateral across-hemisphere interactions or ipsilateral within-hemisphere interactions in left-hemispheric FPN nodes, whereas larger negative values indicate stronger interactions in right-hemispheric FPN nodes. Thus, LIs of FPN, along with neuropsychological assessments (Trail Making Test (TMT) to measure executive function [9] and the WHO-UCLA Auditory Verbal Learning Test (AVLT) to measure episodic memory function [10]), were acquired at three different time points: baseline 0, end of intervention (7-week), and 6-month follow-up. A healthy older group with 30 participants only provided data at baseline 0.

At baseline 0, the two VCIND groups showed a similar lateralization pattern in FPN to healthy older adults (Figure 1A). However, a stronger right-lateralized LI_he correlated with better memory performance only in the healthy older group (Figure 1B). At the end of the 7-week intervention, only the VCIND training group, but not the control group, exhibited reduced lateralization with a bilateralized LI_he in FPN (Figure 2A), where stronger leftward changes were correlated with better executive and memory functions (Figure 2B). Notably, all these changes disappeared at the 6-month follow-up.

Subcortical VCIND impaired the cognitive benefit of right-lateralized FPN typically observed in healthy older adults. Instead of restoring the cognitive reserve with right-lateralizated FPN, the 7-week cognitive training facilitated executive and memory functions through functional compensation by reorganizing and balancing the hemispherical symmetry of FPN. These findings have important implications for understanding and intervening cognitive impairment.

Neurodegenerative/ Late Life (eg. Parkinson’s, Alzheimer’s) ¹

BOLD fMRI ²

Aging

Behavioral Therapy

Cerebrovascular Disease

FUNCTIONAL MRI

Hemispheric Specialization

Psychiatric Disorders