Greetings Earthlings! 🙂
This week I’d like to take a look at another neurological condition that can be co-morbid with autism- dyslexia.
First things first, what is dyslexia?
Dyslexia can be described as a specific type of learning disability that impacts a persons reading, writing and spelling abilities. Impacting approximately 10% of the population, dyslexia ranges from mild to severe characterized by cognitive difficulties with processing phonetics, working memory and speed of long term memory retrieval. Like autism, the exact neurological causes and mechanisms are unclear, but as dyslexia can run in families, genetic factors are largely thought to contribute.
So how is it linked to autism?
The link between autism and dyslexia has not been scientifically established, but there are some commonalities. Interestingly, dyslexia overlaps with many autistic co-morbidities such as ADHD, dysgraphia, dyspraxia (an estimated 52-53% of dyslexics are also dyspraxic), and auditory processing disorders, which would suggest that these conditions likely operate through similar neurological mechanisms and pathways.
Scientists have found it difficult to establish a direct genetic link between the two conditions, however, recent research may implicate gene deletions in CNTNAP5 (a gene involved in connecting neurons) and DOCK4 (a gene that regulates junctions between cells) in both dyslexia and autism. In addition to this, a 2015 study found that declarative memory (the type of memory that can be “declared” like names, facts, figures etc.) can be used to develop coping mechanisms for both autism and dyslexia, suggesting that perhaps there may be overlap in the brain regions associated with this type of memory formation. Other studies exploring the neural mechanisms of dyslexia indicate structural changes in such regions as the frontal lobe (memory and problem solving), cerebellum (the motor centre) and corpus callosum (the bundle of nerves that splits and connects the left and right hemispheres of the brain)- all areas that have also shown structural changes in studies of the autistic brain.
Most recently, a 2021 study exploring the co-occurrence of dyslexia and other neurodevelopmental disorders reported that many dyslexic patients in their dataset also had issues with sensory processing and other ASD traits, but concluded that the links between the two conditions are complex and hard to underpin, especially given that some autists are hyperlexic (guilty!) rather than dyslexic.
Whilst there is no definitive scientific link, the overlap cannot be denied.
Hope you enjoyed this post dear Earthlings! 🙂
Have a lovely weekend!