Brain health imaging markers, post-stroke aphasia and Cognition: A scoping review

Pulse Pressure, White Matter Hyperintensities, and Cognition: Mediating Effects Across the Adult Lifespan

OBJECTIVES

To investigate whether pulse pressure or mean arterial pressure mediates the relationship between age and white matter hyperintensity load and to examine the mediating effect of white matter hyperintensities on cognition.

METHODS

Demographic information, blood pressure, current medication lists, and Montreal Cognitive Assessment scores for 231 stroke- and dementia-free adults were retrospectively obtained from the Aging Brain Cohort study. Total WMH load was determined from T2-FLAIR magnetic resonance scans using the TrUE-Net deep learning tool for white matter segmentation. In separate models, we used mediation analysis to assess whether pulse pressure or MAP mediates the relationship between age and total white matter hyperintensity load, controlling for cardiovascular confounds. We also assessed whether white matter hyperintensity load mediated the relationship between age and cognitive scores.

RESULTS

Pulse pressure, but not mean arterial pressure, significantly mediated the relationship between age and white matter hyperintensity load. White matter hyperintensity load partially mediated the relationship between age and Montreal Cognitive Assessment score.

INTERPRETATION

Our results indicate that pulse pressure, but not mean arterial pressure, is mechanistically associated with age-related accumulation of white matter hyperintensities, independent of other cardiovascular risk factors. White matter hyperintensity load was a mediator of cognitive scores across the adult lifespan. Effective management of pulse pressure may be especially important for maintenance of brain health and cognition.

White Matter Hyperintensity Load Independent From the Stroke Lesion Is Associated With Chronic Aphasia Severity and Treatment Outcome

BACKGROUND

Although many studies have suggested that white matter hyperintensity (WMH) severity predicts naming and aphasia severity in chronic poststroke aphasia, there are inconsistencies in the literature. WMHs are typically symmetrical in neurotypical controls, and measuring WMH in the contralateral hemisphere is likely the best option to estimate brain health independently from the stroke lesion and avoid measurement contamination from stroke-related gliosis. In this study, we aimed to clarify the discrepancies in the literature by testing whether WMH rating methods are related to clinical outcomes.

METHODS

Ninety-five participants with chronic aphasia at least 12 months after their left-hemisphere stroke completed a baseline Western Aphasia Battery and the Philadelphia Naming Test. All participants then underwent 6 weeks of phonological and semantic naming treatments focused on improving lexical processing, and the Philadelphia Naming Test was readministered immediately following treatment. Using the Fazekas scale, WMH severity was independently rated on the whole brain and the right hemisphere only. Their relationship of WMH behavior was calculated by accounting for age, lesion volume, time poststroke, years of education, and sex.

RESULTS

There were significant positive correlations between whole-brain and right-hemisphere ratings of WMH, but Wilcoxon signed-rank tests revealed that whole-brain ratings were consistently higher (whole brain M=3.337, right hemisphere M=2.899; P<0.001). Right hemisphere ratings were more strongly correlated with behavioral measures. There were significant negative correlations between all WMH ratings and behavior at baseline (Western Aphasia Battery Aphasia Quotient and Philadelphia Naming Test) except for whole brain periventricular ratings. However, only right-hemisphere periventricular WMH was significantly associated with therapy-related naming improvements (r=-0.226, R2=0.05, P=0.044).

CONCLUSIONS

Given the regional effect of the stroke lesion, whole-brain ratings can overestimate the WMH burden and thus reduce the accuracy in evaluating small vessel disease effects on stroke recovery and aphasia severity, particularly therapy-related neuroplasticity. This is an important detail that should be considered in mechanistic studies of small vessel disease, brain health, and stroke recovery.

Early subacute frontal callosal microstructure and language outcomes after stroke

The integrity of the frontal segment of the corpus callosum, forceps minor, is particularly susceptible to age-related degradation and has been associated with cognitive outcomes in both healthy and pathological ageing. The predictive relevance of forceps minor integrity in relation to cognitive outcomes following a stroke remains unexplored. Our goal was to evaluate whether the heterogeneity of forceps minor integrity, assessed early after stroke onset (2-6 weeks), contributes to explaining variance in longitudinal outcomes in post-stroke aphasia. Both word- and sentence-level tasks were employed to assess language comprehension and language production skills in individuals with first-ever left-hemisphere stroke during the early subacute and chronic phases of recovery (n = 25). Structural and diffusion neuroimaging data from the early subacute phase were used to quantify stroke lesion load and bilateral forceps minor radial diffusivity. Multiple linear regression models examined whether early subacute radial diffusivity within the forceps minor, along with other factors (stroke lesion load, age, sex and education), explained variance in early subacute performance and longitudinal recovery (i.e. change in behavioural performance). Increased early subacute radial diffusivity in the forceps minor was associated with poor early subacute comprehension (t = -2.36, P = 0.02) but not production (P = 0.35) when controlling for stroke lesion load, age, sex and education. When considering longitudinal recovery, early subacute radial diffusivity in the forceps minor was not linked to changes in performance in either comprehension (P = 0.11) or production (P = 0.36) under the same control variables. The examination of various language components and processes led to novel insights: (i) language comprehension may be more susceptible to white matter brain health than language production and (ii) the influence of white matter brain health is reflected in early comprehension performance rather than longitudinal changes in comprehension. These results suggest that evaluating baseline callosal integrity is a valuable approach for assessing the risk of impaired language comprehension post-stroke, while also underscoring the importance of nuanced analyses of behavioural outcomes to enhance our understanding of the clinical applicability of baseline brain health measures.

Cerebral small vessel disease is an independent determinant of dysphagia after acute stroke

BACKGROUND

The high incidence of dysphagia after acute stroke is likely the result of cumulative effects of the stroke and pre-stroke brain health. While cerebral small vessel disease (cSVD) is recognized as a marker of compromised brain health, it's unclear which neuroanatomical pathologies of cSVD impact post-stroke dysphagia. We assessed the relation between cSVD pathologies, i.e., brain atrophy, white matter hyperintensities (WMH), perivascular spaces, as markers for brain integrity at the time of the stroke, and acute post-stroke dysphagia measured with the Modified Barium Swallow Study (MBSS).

METHODS

We conducted a retrospective, observational study of 40 individuals with an acute first-ever ischemic stroke. We segmented T1-weighted images into gray matter, white matter, and cerebrospinal fluid (CSF) to derive brain atrophy estimates. We scored the presence and severity of periventricular and deep WMH using the Fazekas scale and counted perivascular spaces in the basal ganglia following standard guidelines. Swallow impairments were determined with the Modified Barium Swallow Impairment Profile (MBSImP), Penetration-Aspiration Scale, and timing measures (oral (OTT), and pharyngeal transit times (PTT)). We performed regression to assess the relation between cSVD pathologies and swallowing while controlling for the stroke overlap with the right and left corticobulbar tracts, stroke volume, and the number of days between the MRI and MBSS.

RESULTS

Worse brain atrophy and more severe periventricular WMH were related to more severe MBSImP pharyngeal total scores, and worse deep WMH were related to aspiration events. More severe perivascular spaces in the basal ganglia were related to longer OTT and PTT, with a high explanatory value (27.5% and 25.1%, respectively), even when controlling for chronological age.

CONCLUSIONS

Our results suggest that several aspects of pre-stroke brain health impact dysphagia severity after acute stroke independent of the stroke site and size. These findings contribute to our understanding of mechanisms underlying the variability of post-stroke dysphagia and emphasize the importance of brain structural integrity before the stroke. Future larger studies are warranted.

The effect of transcranial magnetic stimulation on cognitive function in post-stroke patients: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Transcranial magnetic stimulation (TMS) is considered as a promising treatment option for post-stroke cognitive impairment (PSCI).Some meta-analyses have indicated that TMS can be effective in treating cognitive decline in stroke patients, but the quality of the studies included and the methodologies employed were less than satisfactory. Thus, this meta-analysis aimed to evaluate the efficacy and safety of TMS for treating post-stroke cognitive impairment.

METHODS

We searched online databases like PubMed, Embase, Cochrane Library, and Web of Science to retrieve randomized controlled trials (RCTs) of TMS for the treatment of patients with PSCI. Two independent reviewers identified relevant literature, extracted purpose-specific data, and the Cochrane Risk of Bias Assessment Scale was utilized to assess the potential for bias in the literature included in this study. Stata 17.0 software was used for data analysis.

RESULTS

A total of 10 studies involving 414 patients were included. The results of the meta-analysis showed that TMS was significantly superior to the control group for improving the overall cognitive function of stroke patients (SMD = 1.17, 95% CI [0.59, 1.75], I2 = 86.1%, P < 0.001). Subgroup analyses revealed that high-frequency rTMS (HF-rTMS), low-frequency rTMS (LF-rTMS), and intermittent theta burst stimulation (iTBS) all have a beneficial effect on the overall cognitive function of stroke patients. However, another subgroup analysis failed to demonstrate any significant advantage of TMS over the control group in terms of enhancing scores on the Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) and Rivermead Behavioral Memory Test (RBMT) scales. Nonetheless, TMS demonstrated the potential to enhance the recovery of activities of daily living in stroke patients, as indicated by the Modified Barthel Index (MBI) (SMD = 0.76; 95% CI [0.22, 1.30], I2 = 52.6%, P = 0.121).

CONCLUSION

This meta-analysis presents evidence supporting the safety and efficacy of TMS as a non-invasive neural modulation tool for improving global cognitive abilities and activities of daily living in stroke patients. However, given the limited number of included studies, further validation of these findings is warranted through large-scale, multi-center, double-blind, high-quality randomized controlled trials.

PROSPERO REGISTRATION NUMBER

CRD42022381034.

Cognitive behavioural therapy for depression, quality of life, and cognitive function in the post-stroke period: systematic review and meta-analysis

The post-stroke period is associated with a lot of sequelae, including depression, decreased quality of life, and decline of cognitive function. Apart from the pharmacotherapy, it is also important to find a non-pharmacological treatment to relieve the sequelae. Cognitive behavioural therapy (CBT) might be a potential candidate, which can be clarified by a systematic review and meta-analysis. The eligible criteria of enrolled studies in the systematic review and meta-analysis were the randomised clinical trials (RCTs) using CBT to treat post-stroke depression, or with the focus on quality of life or cognitive function in the post-stroke period. The endpoint scores of depression, quality of life, and cognitive function scales were the targeted outcome for the final meta-analysis in the random effects model. Ten RCTs with 432 post-stroke patients receiving CBT and 385 controls were included. The meta-analysis results showed significant improvements in depression severity and quality of life. However, no significant difference between CBT and control groups was found in cognitive function. In addition, significant heterogeneity was derived from the meta-analysis. According to the meta-analysis results, CBT might be beneficial for relieving depression severity and improving quality of life. However, cognitive function might not be influenced by CBT. Further studies with a more consistent CBT design with greater sample sizes should be warranted to clarify and confirm the treatment effects of CBT for post-stroke depression and quality of life.

Under pressure: the interplay of hypertension and white matter hyperintensities with cognition in chronic stroke aphasia

While converging research suggests that increased white matter hyperintensity load is associated with poorer cognition, and the presence of hypertension is associated with increased white matter hyperintensity load, the relationship among hypertension, cognition and white matter hyperintensities is not well understood. We sought to determine the effect of white matter hyperintensity burden on the relationship between hypertension and cognition in individuals with post-stroke aphasia, with the hypothesis that white matter hyperintensity load moderates the relationship between history of hypertension and cognitive function. Health history, Fazekas scores for white matter hyperintensities and Wechsler Adult Intelligence Scale Matrix Reasoning subtest scores for 79 people with aphasia collected as part of the Predicting Outcomes of Language Rehabilitation study at the Center for the Study of Aphasia Recovery at the University of South Carolina and the Medical University of South Carolina were analysed retrospectively. We found that participants with a history of hypertension had increased deep white matter hyperintensity severity (P < 0.001), but not periventricular white matter hyperintensity severity (P = 0.116). Moderation analysis revealed that deep white matter hyperintensity load moderates the relationship between high blood pressure and Wechsler Adult Intelligence Scale scores when controlling for age, education, aphasia severity and lesion volume. The interaction is significant, showing that a history of high blood pressure and severe deep white matter hyperintensities together are associated with poorer Matrix Reasoning scores. The overall model explains 41.85% of the overall variation in Matrix Reasoning score in this group of participants. These findings underscore the importance of considering cardiovascular risk factors in aphasia treatment, specifically hypertension and its relationship to brain health in post-stroke cognitive function.

[Clinical and tomographic comparisons in patients with aphasia in the acute period of ischemic stroke]

OBJECTIVE

To investigate the structural damage in patients with aphasia in the acute phase of ischemic stroke using X-ray computed tomography (CT) scans of the brain.

MATERIAL AND METHODS

We examined 65 right-handed individuals in the acute stage of ischemic stroke in the left middle cerebral artery, including 39 men and 26 women aged 41 to 87 years. The patients were divided into two groups: those with aphasia (group 1, n=48) and those without aphasia (group 2, n=17). All participants underwent head CT scans on the first day of hospitalization and again 24 to 48 hours later, as well as CT angiography of the intracranial and brachiocephalic arteries.

RESULTS

Atherothrombotic and cardioembolic pathogenic subtypes of ischemic stroke were significantly more common in group 1, while lacunar subtypes were more common in group 2 (χ2=13.608, p=0.004). Most patients had a mild to moderate stroke, but the severity and degree of disability were significantly greater in group 1. There was also a significant difference in the size of cerebral infarction (25.7±19.9 versus 3.1±3.5 cm³, p<0.001). More than 75% of patients in group 1 had lesions in speech representation areas and adjacent regions of the left cerebral cortex, and more than 90% had involvement of the speech network tracts within the infarction zone (compared to 0 and 11.8% in group 2, respectively, p<0.001).

CONCLUSION

The results confirm the role of speech disorders in the level of disability after ischemic stroke. The significance of damage to both cortical representations and the conductors of the speech network is shown. This can affect the prognosis for speech function restoration, as well as allowing for personalized modeling of a rehabilitation program for these patients.

Insights gained over 60 years on factors shaping post-stroke aphasia recovery: A commentary on Vignolo (1964)

Aphasia is an acquired language disorder resulting from brain injury, including strokes which is the most common etiology, neurodegenerative diseases, tumors, traumatic brain injury, and resective surgery. Aphasia affects a significant portion of stroke survivors, with approximately one third experiencing its debilitating effects in the long term. Despite its challenges, there is growing evidence that recovery from aphasia is possible, even in the chronic phase of stroke. Sixty years ago, Vignolo (1964) outlined the primary challenges confronted by researchers in this field. These challenges encompassed the absence of an objective evaluation of language difficulties, the scarcity of evidence regarding spontaneous aphasia recovery, and the presence of numerous variables that could potentially influence the process of aphasia recovery. In this paper, we discuss the remarkable progress that has been made in the assessment of language and communication in aphasia as well as in understanding the factors influencing post-stroke aphasia recovery.