Resting-State Beta-Band Recovery Network Related to Cognitive Improvement After Stroke

Background

Stroke is the second leading cause of death worldwide and it causes important long-term cognitive and physical deficits that hamper patients' daily activity. Neuropsychological rehabilitation (NR) has increasingly become more important to recover from cognitive disability and to improve the functionality and quality of life of these patients. Since in most stroke cases, restoration of functional connectivity (FC) precedes or accompanies cognitive and behavioral recovery, understanding the electrophysiological signatures underlying stroke recovery mechanisms is a crucial scientific and clinical goal.

Methods

For this purpose, a longitudinal study was carried out with a sample of 10 stroke patients, who underwent two neuropsychological assessments and two resting-state magnetoencephalographic (MEG) recordings, before and after undergoing a NR program. Moreover, to understand the degree of cognitive and neurophysiological impairment after stroke and the mechanisms of recovery after cognitive rehabilitation, stroke patients were compared to 10 healthy controls matched for age, sex, and educational level.

Findings

After intra and inter group comparisons, we found the following results: (1) Within the stroke group who received cognitive rehabilitation, almost all cognitive domains improved relatively or totally; (2) They exhibit a pattern of widespread increased in FC within the beta band that was related to the recovery process (there were no significant differences between patients who underwent rehabilitation and controls); (3) These FC recovery changes were related with the enhanced of cognitive performance. Furthermore, we explored the capacity of the neuropsychological scores before rehabilitation, to predict the FC changes in the brain network. Significant correlations were found in global indexes from the WAIS-III: Performance IQ (PIQ) and Perceptual Organization index (POI) (i.e., Picture Completion, Matrix Reasoning, and Block Design).

Self-Awareness Moderates the Association Between Executive Dysfunction and Functional Independence After Acquired Brain Injury

OBJECTIVE

Impaired self-awareness (SA) is a common symptom after suffering acquired brain injury (ABI) which interferes with patient's rehabilitation and their functional independence. SA is associated with executive function and declarative memory, two cognitive functions that are related to participants' daily living functionality. Through this observational study, we aim to explore whether SA may play a moderator role in the relation between these two cognitive processes and functional independence.

METHOD

A sample of 69 participants with ABI completed a neuropsychological assessment focused on executive function and declarative memory which also included a measure of SA and functional independence. Two separated linear models were performed including functional independence, SA, and two neuropsychological factors (declarative memory and executive function) derived from a previous principal component analysis.

RESULTS

Moderation analysis show a significant interaction between SA and executive function, reflecting an association between lower executive functioning and poorer functional outcome, only in participants with low levels of SA. Notwithstanding, declarative memory do not show a significant interaction with SA, even though higher declarative memory scores were associated with better functional independence.

CONCLUSIONS

SA seems to play a moderator effect between executive function, but not declarative memory, and functional independence. Accordingly, participants with executive deficits and low levels of SA might benefit from receiving specific SA interventions in the first instance, which would in turn positively impact on their functional independence.

Cognitive predictors of self-awareness in patients with acquired brain injury along neuropsychological rehabilitation

Previous research has identified a critical role of executive function and memory in self-awareness, a metacognitive capacity often impaired in acquired brain injury. Through this observational study, we aimed to explore the effect of cognitive rehabilitation on the predictive value of these variables, as also whether any of them can predict the level of self-awareness once the cognitive rehabilitation is completed. 69 patients underwent a neuropsychological assessment, including self-awareness, at admission to and discharge from a cognitive rehabilitation process. Regression analysis was performed at these two moments and a third one was conducted to evaluate whether any of the variables at admission predicted the level of self-awareness at discharge. Verbal fluency was found to be the best predictor of self-awareness, both at admission and discharge. In addition, inhibition and cognitive flexibility, as well as episodic memory, appeared as significant predictors of post-rehabilitation self-awareness. Finally, verbal fluency was revealed as the unique pre-rehabilitation predictor of subsequent level of self-awareness following rehabilitation. While post-acute self-awareness is predicted by non-specific executive measures, the cognitive improvement putatively induced by neuropsychological rehabilitation reveals the contribution of more specific executive and memory functions. Importantly, pre-rehabilitation verbal fluency scores predicted the level of self-awareness after cognitive rehabilitation.