The volume and the distribution of premorbid white matter hyperintensities: Impact on post-stroke aphasia

White matter hyperintensities (WMH) are a radiological manifestation of progressive white matter integrity loss. The total volume and distribution of WMH within the corpus callosum have been associated with pathological cognitive ageing processes but have not been considered in relation to post-stroke aphasia outcomes. We investigated the contribution of both the total volume of WMH, and the extent of WMH lesion load in the corpus callosum to the recovery of language after first-ever stroke. Behavioural and neuroimaging data from individuals (N = 37) with a left-hemisphere stroke were included at the early subacute stage of recovery. Spoken language comprehension and production abilities were assessed using word and sentence-level tasks. Neuroimaging data was used to derive stroke lesion variables (volume and lesion load to language critical regions) and WMH variables (WMH volume and lesion load to three callosal segments). WMH volume did not predict variance in language measures, when considered together with stroke lesion and demographic variables. However, WMH lesion load in the forceps minor segment of the corpus callosum explained variance in early subacute comprehension abilities (t = -2.59, p = .01) together with corrected stroke lesion volume and socio-demographic variables. Premorbid WMH lesions in the forceps minor were negatively associated with early subacute language comprehension after aphasic stroke. This negative impact of callosal WMH on language is consistent with converging evidence from pathological ageing suggesting that callosal WMH disrupt the neural networks supporting a range of cognitive functions.

Exploring the usability and feasibility of a mobile music listening application for people living in the community with post-stroke aphasia

PURPOSE

Language and communication disorders can inhibit participation in activities that have potential therapeutic benefits for recovery. This exploratory research examined the usability and feasibility of a purpose-built music listening mobile application for people living in the community with post-stroke aphasia, and examined relationships between useability and participant age, aphasia severity and time post-stroke.

METHODS

Nineteen participants with chronic aphasia tested the application for two weeks. Prior to use, music preferences, technology use and confidence, self-efficacy and music engagement questionnaires were completed. System usability scale, music listening data and a satisfaction rating were completed following use.

RESULTS

Overall, the application was perceived as being usable and feasible with a high system usability rating and moderate effectiveness, efficiency and satisfaction. The system usability scores were not associated with aphasia severity, age, years post-stroke, self-efficacy or music engagement. Technology confidence was positively associated with system usability.

CONCLUSION

The music listening application is a feasible and usable option for listening to music in people with chronic post-stroke aphasia. This study provides a foundation for the rigorous examination of the usability of music listening technology for people with post-stroke aphasia and the potential investigation of use in acute care facilities and other clinical populations.IMPLICATIONS FOR REHABILITATIONMusic listening has potential therapeutic benefits for people with post-stroke aphasia.Applications for music listening require customisation to enable people with post-stroke aphasia opportunity to listen to their preferred music.Music listening applications that are perceived as usable and feasible by people with post-stroke aphasia may have potential application within rehabilitation and community settings.

Early Subacute White Matter Hyperintensities and Recovery of Language After Stroke

BACKGROUND

White matter hyperintensities (WMH) are considered to contribute to diminished brain reserve, negatively impacting on stroke recovery. While WMH identified in the chronic phase after stroke have been associated with post-stroke aphasia, the contribution of premorbid WMH to the early recovery of language across production and comprehension has not been investigated.

OBJECTIVE

To investigate the relationship between premorbid WMH severity and longitudinal comprehension and production outcomes in aphasia, after controlling for stroke lesion variables.

METHODS

Longitudinal behavioral data from individuals with a left-hemisphere stroke were included at the early subacute (n = 37) and chronic (n = 28) stage. Spoken language comprehension and production abilities were assessed at both timepoints using word and sentence-level tasks. Magnetic resonance imaging (MRI) was performed at the early subacute stage to derive stroke lesion variables (volume and proportion damage to critical regions) and WMH severity rating.

RESULTS

The presence of severe WMH explained an additional 18% and 25% variance in early subacute (t = -3.00, p = .004) and chronic (t = -3.60, P = .001) language comprehension abilities respectively, after controlling for stroke lesion variables. WMH did not predict additional variance of language production scores.

CONCLUSIONS

Subacute clinical MRI can be used to improve prognoses of recovery of aphasia after stroke. We demonstrate that severe early subacute WMH add to the prediction of impaired longitudinal language recovery in comprehension, but not production. This emphasizes the need to consider different domains of language when investigating novel neurobiological predictors of aphasia recovery.

Right hemispheric structural connectivity and poststroke language recovery

Poststroke aphasia typically results from brain damage to the left-lateralized language network. The contribution of the right-lateralized homologues in aphasia recovery remains equivocal. In this longitudinal observational study, we specifically investigated the role of right hemisphere structural connectome in aphasia recovery. Twenty-two patients with aphasia after a left hemispheric stroke underwent comprehensive language assessment at the early subacute and chronic stages. A novel structural connectometry approach, using multi-shell diffusion-weighted MRI data collected at the early subacute stage, was used to evaluate the relationship between right hemisphere white matter connectome and language production and comprehension abilities at early subacute stage. Moreover, we evaluated the relationship between early subacute right hemisphere white matter connectome and longitudinal change in language production and comprehension abilities. All results were corrected for multiple comparisons. Connectometry analyses revealed negative associations between early subacute stage right hemisphere structural connectivity and language production, both cross-sectionally and longitudinally (p_FDR  < .0125). In turn, only positive associations between right hemisphere structural connectivity and language comprehension were observed, both cross-sectionally and longitudinally (p_FDR  < .0125). Interhemispheric connectivity was highly associated with comprehension scores. Our results shed light on the discordant interpretations of previous findings, by providing evidence that while some right hemisphere white matter pathways may make a maladaptive contribution to the recovery of language, other pathways support the recovery of language, especially comprehension abilities.

An fMRI Study of Concreteness Effects during Spoken Word Recognition in Aging. Preservation or Attenuation?

It is unclear whether healthy aging influences concreteness effects (i.e., the processing advantage seen for concrete over abstract words) and its associated neural mechanisms. We conducted an fMRI study on young and older healthy adults performing auditory lexical decisions on concrete vs. abstract words. We found that spoken comprehension of concrete and abstract words appears relatively preserved for healthy older individuals, including the concreteness effect. This preserved performance was supported by altered activity in left hemisphere regions including the inferior and middle frontal gyri, angular gyrus, and fusiform gyrus. This pattern is consistent with age-related compensatory mechanisms supporting spoken word processing.