The last post described our recently completed Phase II Clinical Trial using non-invasive brain stimulation as an adjunct to aphasia treatment. See this link for details. Briefly, that post described results from the trial, which found that anodal transcranial direct current stimulation (A-tDCS) is safe, and further study of A-tDCS for aphasia is warranted.
This post provides more information about why some participants recovered more than others, even those who received the active stimulation. The article that describes this study is published in the journal Brain Stimulation. You can find the article by following this link: A-tDCS and Aphasia. Read on for details of that study.
A-tDCS and Neuroplasticity
A-tDCS has been shown to improve aphasia outcomes, but there are many questions about why it works. Researchers have suggested that A-tDCS affects neuroplasticity. Neuroplasticity is a term used to describe how the brain changes in response to something. For example, when we learn new things, our brain changes. These changes can occur at the synapses – the connections between neurons.
Do certain genes facilitate treatment?
There is a gene that has been shown to influence neuroplasticity. This gene is called the brain-derived neurotrophic factor (BDNF). Everyone has the BDNF gene, but some people have different genotypes. There may be differences in neuroplasticity based on a person’s genotype. Therefore, the rationale behind this study was the following:
- If BDNF affects neuroplasticity, and
- A-tDCS affects neuroplasticity,
- then individuals with “typical” BDNF expression may benefit more from A-tDCS.
In our analysis, we did find that those who were “typical” BDNF carriers made even greater progress after A-tDCS treatment. It is possible that the “typical” BDNF gene carriers release more BDNF, which amplified the effects of the brain stimulation treatment (see an illustration below).Currently, this study is only one of two studies that have considered the role of BDNF in aphasia treatment outcomes. This means that more research is needed to understand this relationship. As we continue to study BDNF and its role in treatment, we will learn more about different factors that influence aphasia recovery.