Initially, the review explains four possible mechanisms for the interference:
- A capacity-sharing problem, where limited processing power by the brain must be shared beween tasks, so one or both tasks gets less;
- A bottleneck problem, where internal processing can only attend to one task at a time;
- A combination of the above two problems; and
- A cross-talk problem, wherein information in one communication channel transfers across into another channel. Interestingly, the cross-talk mechanism doesn't always cause a deterioration. Sometimes, it can faciliate better performance of one or both tasks.
The rest of the review focused on dual tasks in stroke where one of the tasks was walking. When the data from the included studies were pooled statistically, the most common patern of dual-task interference was mutual interference – that is, a decrement in both walking and the other task during dual tasking. The amount and pattern of dual-task interference didn't seem to vary between acute or chronic stroke.
In studies where the secondary task was a mental task (e.g., mathematical subtractions) rather than a physical task (e.g., carrying a tray of glasses), there was the greatest amount of dual-task interference. The pattern and amount of dual-task interference was similar between mental and physical secondary tasks.
When evaluating mobility and planning rehabilitation, clinicians should select dual-task assessments that correspond to the daily habits and physical demands of people after stroke.
> From: Tsang, J Physiother 68 (2022) 26-36 (Epub ahead of print). All rights reserved to Australian Physiotherapy Association. Click here for the online summary.
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