Up to 70% of stroke survivors complain of tiredness or fatigue, sometimes years after stroke. However, unlike normal tiredness, post-stroke fatigue doesn't always respond to rest. We don't know what causes this extreme tiredness and there are no effective treatments available.
The researchers working on this study previously investigated how excitable (i.e. how responsive to stimulation) the motor cortex, the area of the brain responsible for movement, is. They found that the excitability of the motor cortex was low in stroke survivors with high levels of fatigue.
While this is a promising finding, it doesn't tell us whether the high levels of fatigue caused low excitability of the brain's motor cortex, or whether low motor cortex excitability caused higher levels of fatigue. It's important that we know which causes which so that we can develop treatments. For example, if low excitability of the motor cortex causes higher levels of fatigue, then it might be possible to develop a treatment that involves stimulating and increasing the excitability of the motor cortex, reducing the amount of fatigue a stroke survivor experiences.
This study will test 64 stroke survivors with high levels of fatigue. Half of the participants will receive a safe, non-invasive type of brain stimulation called transcranial direct current stimulation (tDCS) to the motor cortex of their brain every day for 5 days. The rest will receive a dummy/sham treatment that will simulate the experience of receiving real tDCS brain stimulation.
The researchers will measure the excitability of the motor cortex of all of the participants before and after they receive the real or 'sham' stimulation. They will also measure levels of fatigue and other physical and brain functions to look at the impact of the tDCS stimulation. The researchers think that fatigue levels will decrease following real tDCS but not after the sham tDCS.
The results of the study could provide a new direction to fatigue treatment after stroke. Fatigue is generally seen as a complaint associated with mood problems (for example: depression), but this research may show that fatigue after stroke is related to low excitability levels of the brain and that treatments should be created which will increase the excitability of the affected brain areas.