Discussion
stroke, cognitive impairments, visuospatial/executive impairments, visuospatial and executive impairments, Cognitive impairments
STROKE, RECRUITMENT
The current study indicates that associations between visuospatial and executive function and activity performance, previously demonstrated in the early stage after stroke, remain long-term. Notably, visuospatial/executive function was associated with the effect of conventional gait training both at 6 weeks and 6 months, where a higher level of visuospatial/executive function indicated a larger improvement. In the HAL-group no such association was found, indicating improvements all over the spectrum of assessed visuospatial/executive function. Executive function rated by significant others did not present any notable associations.Cognitive impairments in general have been associated with activity performance in several studies in the acute and subacute stages [Visuospatial and executive function have been positively associated with long-term improvement in balance, up to one year after stroke [In the analysis of the association between visuospatial/executive function and the effect of the gait interventions, a larger impact on walking distance and -speed was seen at 6 months, compared to 6 weeks. These results indicate that generalization of training results to everyday activities can be negatively affected by visuospatial and executive impairments impacting on problem-solving, interpretation of the body and environment, processing of feedback, self-regulation and initiative [When comparing the groups separately, the HAL-group gained improvements in walking distance at 6 months all over the spectrum of assessed visuospatial/executive function. In contrast, the conventional group showed that visuospatial/executive function was associated with the outcome of the gait intervention, where those with a lower score generally acquired small or no improvements at 6 weeks and 6 months. Based on these results, it is plausible that HAL-training may be more suitable than conventional gait training for participants with more severe visuospatial/executive impairments. On the other hand, for those with more preserved visuospatial/executive function, conventional gait training seems to have more beneficial effects in terms of MCID, indicating cognitive capacity enabling engagement in rehabilitation interventions and generalization to everyday activities, promoting long-term sustainability of achieved improvements.Considering the association between level of visuospatial/executive impairments and limitations in walking, as shown in the baseline analysis, finding effective gait training interventions for people with visuospatial and executive impairments is crucial. Since the HAL-training is both task-specific and repetitive, HAL-training may have the potential to improve walking ability among patients with more severe visuospatial/executive impairments. Theories of neuroplasticity in the central nervous system support this hypothesis, where a reorganization of recruitment patterns and -areas in the brain can be seen as a response to altered input and demands, both in healthy subjects and in a stroke population [Although participants with visuospatial/executive impairments gained improvement at 6 months in the HAL-group, only a few acquired effects exceeding the MCID. These results can though be set in comparison to the control group, where a decline in walking distance at 6 months was seen. The results further imply that even with a well preserved visuospatial/executive function, a decline in activity performance may be seen long-term. This highlights the need of individualized interventions to preserve activity performance over time, even long-term after stroke when rehabilitation interventions usually are sparse [Results from this study may not be generalized to the whole stroke population but targets a younger subgroup living with moderately severe impairments and limitations in walking long-term after stroke.The measures used for evaluating the visuospatial and executive function were MoCA Vis/Ex as a clinical assessment of visuospatial and executive function, as well as the DEX-SO for the perceived everyday impairments related to executive function. The MoCA is commonly used in clinical contexts and assesses multiple domains of cognition, enabling the use of sub scores for specific domains [In the data analysis, action was taken to prevent errors due to multiple comparisons (Type-1 error) by applying the adjusted alpha level. On the other hand, the relatively small number of participants in the analysis of the association between visuospatial/executive function and the effect of gait training, can limit the ability of reaching statistical significance, as a Type-2 error. Altogether, the few significant associations presented can be assumed robust, results not reaching statistical significance can still be discussed as they might show tendencies of interest for future research. In the analysis of the groups separately, the results must be considered preliminary, due to the low number of participants, where changes or drop-outs of a few participants may have affected the results.As described earlier, it is of great importance to investigate the effect of cognitive impairments on rehabilitation outcome, since it has been associated with poorer activity performance, both short- and long term after stroke [