Summary of an article published first in Perspectives of the ASHA Special Interest Groups SIG 2, Vol. 2 (Part 1), 2017.
Authors: Sofia Vallila-Rohter & Swathi Kiran
SUMMARY OF RESEARCH
Aphasia is complex – although we can generally categorize it into groups, such as global aphasia, anomic aphasia, transcortical motor aphasia, etc., based on general presentation, no one person has the exact same set of strengths and weaknesses as another person with Aphasia. The brain is a complex system of neural networks that team up to produce language and help us to think clearly. We often hear that Aphasia is a loss of language, not cognition. But what if that’s not telling the entire story?
People with Aphasia do not inherently have cognitive deficits – indeed, Aphasia is characterized by challenges in processing and producing language. However, as with all things neurologic, language does not happen in isolation. There is a growing body of evidence and research that suggests that Aphasia can also be affected and compounded by specific, and often invisible, cognitive deficits. Vallilla-Rohter and Kiran (2017) recently wrote a guest editor’s column in the Perspectives of the ASHA Special Interest Groups publication that suggests that some higher types of cognition, including attention, executive function (how well your brain organizes and plans), cognitive control, and learning may affect the language and language rehabilitation of a person with Aphasia. And of course, no one person will have the exact same presentation of language and/or cognitive challenges.
Based on the research, there are at least two important neural networks affecting how a person with Aphasia presents.
First, there is the language network – this one is a given. We know that there will be breakdowns in the language network for a person with Aphasia because it is a language disorder.
The second network, called the “domain general network”, is where things get interesting. This network kicks in whenever you are doing something particularly challenging, whether it’s math or reading a complex poem that requires you to make inferences. It makes sense then that studies have found that patients with Aphasia use their domain general network even when comprehending simple sentences – language has become something that is hard.
This domain general network supports attention, which is necessary for understanding language. If you are not able to pay attention to language, how can you understand it? It also includes cognitive control – take for example bilingual speakers – these speakers must control which language is turned on or off. This control goes beyond simply understanding or expressing language – it requires a level of cognitive control that may also be impacted for persons with Aphasia. Additionally, learning systems may be affected in persons with Aphasia; this is especially impactful when deciding what type of rehabilitation tasks and exercises are the best fit for a specific person – you need to be able to learn new information for rehabilitation to be effective.
In short, Aphasia is definitely a language disorder – but the research is telling us that there’s more to it than just language.
The brain does not work in isolation, and neither should our rehabilitation. We need to start taking into account cognitive skills such as attention, executive function, cognitive control, and learning when we select the best treatment options for persons with Aphasia.