Patterns of cognitive-motor dual-task interference post stroke: an observational inpatient study at hospital discharge.

Background Many ambulatory stroke survivors are discharged to community settings where they will confront highly attention-demanding mobility situations. Very little is known about cognitive-motor interference during walking in acutely rehabilitating stroke survivors. Aim To examine the magnitude and patterns of cognitive-motor dual-task interference at hospital discharge post stroke and explore the characteristics associated with distinct interference patterns. Design Observational study. Setting Acute care and inpatient rehabilitation centers. Population 47 adults with hospital admission for stroke who were being discharged to home. Mean age was 59.5 years (SD=11.7) and median days post stroke was 14 (IQR=7-21). Methods Gait and cognitive (category naming task) performance were assessed under singleand dual-task conditions at hospital discharge. Dependent variables were gait speed, stride duration, stride duration variability, stride length, cadence, and correct response rate. Single and dual-task values were compared to assess the effects of dual-tasking on gait and category naming. Relative dual-task effects on gait speed and cognitive performance were plotted to identify patterns of dual-task interference. Exploratory analysis compared clinical characteristics between subgroups defined by pattern of interference. Results There were significant dual-task declines in gait speed, with corresponding dual-task effects on stride length, cadence, and stride duration, but no dual-task effects on stride duration variability or correct response rate. Dual-task effects on the category naming task were not significant due to large between-subject variability. Three predominant patterns of cognitivemotor interference were evident: mutual interference (37% of participants), gait interference (30% of participant), and cognitive-priority trade-off (22% of participants) - these patterns reflect the consistently observed negative dual-task effect on gait speed with positive, negative, or null effects on category naming. Participants who demonstrated cognitive-priority trade-off pattern of interference had significantly worse single-task category-naming performance, while those with mutual interference had greater overall stroke severity. Conclusions Cognitive-motor dual-task interference on gait speed is highly prevalent in ambulatory stroke survivors with mild cognitive-linguistic impairments at hospital discharge. Variability in cognitive-task performance under dual-task conditions has implications for the reliability of dual-task assessment after stroke. Clinical rehabilitation impact Assessment of dual-task walking is feasible as a predischarge evaluation of attention-demanding mobility function after stroke.