Longitudinal Brain Changes After Stroke and the Association With Cognitive Decline

Abstract

BackgroundCognitive impairment is common after stroke. So is cortical- and subcortical atrophy, with studies reporting more atrophy in the ipsilesional hemisphere than the contralesional hemisphere. The current study aimed to investigate the longitudinal associations between (I) lateralization of brain atrophy and stroke hemisphere, and (II) cognitive impairment and brain atrophy after stroke. We expected to find that (I) cortical thickness and hippocampal-, thalamic-, and caudate nucleus volumes declined more in the ipsilesional than the contralesional hemisphere up to 36 months after stroke. Furthermore, we predicted that (II) cognitive decline was associated with greater stroke volumes, and with greater cortical thickness and subcortical structural volume atrophy across the 36 months.MethodsStroke survivors from five Norwegian hospitals were included from the multisite-prospective “Norwegian Cognitive Impairment After Stroke” (Nor-COAST) study. Analyses were run with clinical, neuropsychological and structural magnetic resonance imaging (MRI) data from baseline, 18- and 36 months. Cortical thicknesses and subcortical volumes were obtained via FreeSurfer segmentations and stroke lesion volumes were semi-automatically derived using ITK-SNAP. Cognition was measured using MoCA.ResultsFindings from 244 stroke survivors [age = 72.2 (11.3) years, women = 55.7%, stroke severity NIHSS = 4.9 (5.0)] were included at baseline. Of these, 145 (59.4%) had an MRI scan at 18 months and 72 (49.7% of 18 months) at 36 months. Most cortices and subcortices showed a higher ipsi- compared to contralesional atrophy rate, with the effect being more prominent in the right hemisphere. Next, greater degrees of atrophy particularly in the medial temporal lobe after left-sided strokes and larger stroke lesion volumes after right-sided strokes were associated with cognitive decline over time.ConclusionAtrophy in the ipsilesional hemisphere was greater than in the contralesional hemisphere over time. This effect was found to be more prominent in the right hemisphere, pointing to a possible higher resilience to stroke of the left hemisphere. Lastly, greater atrophy of the cortex and subcortex, as well as larger stroke volume, were associated with worse cognition over time and should be included in risk assessments of cognitive decline after stroke.

Morphological alterations of contralesional hemisphere relate to functional outcomes after stroke

“…In terms of SBM analysis, poststroke patients exhibited decreased CT in the contralesional PreCG, lingual and fusiform gyrus, and IPL, in accordance with several previous studies (Aamodt et al, 2022; Salah Khlif et al, 2022), mirroring the atrophy of the contralesional hemisphere. There are several factors that can account for the thinning of the contralesional cortex, including ‘transcallosal diaschisis’, apoptosis induced by ipsilesional interneurons, Wallerian or retrograde degeneration of fibre tracts, and ‘non‐use cortical atrophy’ (Carrera & Tononi, 2014; Cheng et al, 2020; Kraemer et al, 2004).…”

Dopaminergic mesolimbic structural reserve is positively linked to better outcome after severe stroke

“…Significances are indicated by asterisks. For sensitivity analyses, surviving correlative outcome models were re-computed while iteratively taking various potentially confounding factors into account: (i) side of the lesion including its interaction with the regional volume to account for hemispheric specialization of basal ganglia 48-50 and possible lateralization effects 51 and differential plasticity rates 52 known from traumatic brain injury patients; (ii) peak width of skeletonized mean diffusivity (PSMD) of the unaffected hemisphere as a marker of cerebral small vessel disease burden 53 ; and (iii) influence of initial symptom severity onto volumetry–outcome relationship as operationalized by the interaction between NIHSS (dichotomized by median split into higher and lower NIHSS scores) and regional volume. For specificity analyses, we computed additional outcome models which included only global—and not regional—parameters of structural reserve that are (i) TIV; (ii) averaged grey subcortical matter volume; and (iii) averaged cortical grey matter volume of the unaffected hemisphere.…”

Ability of Local Clearance of Senescent Cells in Ipsilateral Hemisphere to Mitigate Acute Ischemic Brain Injury in Mice

“… 40 Longitudinal tracking is therefore required to record potential pathological changes following stroke. 41 PET imaging is a strong tool in both research and clinical use because it has been used for metabolic-biochemical-molecular studies in vivo and in a minimally invasive manner. 42 , 43 Studies using 18F-FDG in both preclinical and clinical settings have consistently reported that 18F-FDG absorption is lower in areas thought to be the site of ischemic injury.…”