A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Summer, 2022 | Number 3, Volume 36

Rates of ASD higher in people with synesthesia, first-degree relatives

There is an increased incidence of autism spectrum disorders (ASD) in people with synesthesia and their relatives, according to a new study by British researchers. 

Synesthesia is a condition in which sensory stimuli in one modality trigger additional sensations in the same modality or sensations in a different modality. For example, a person seeing the written letter “a” may experience a visual sensation of the color red, or a person hearing the word “hello” may experience the taste of bacon. 

Max Nugent and Jamie Ward evaluated 282 adults with synesthesia and 281 controls. The researchers report that rates of ASD were higher in individuals with synesthesia and their first-degree relatives than in the controls. While there is some suggestive evidence for a link between synesthesia and schizophrenia, the researchers detected no increase in schizophrenia in people with synesthesia. They also detected no link between synesthesia and type 1 diabetes, which was selected to control for the effects of medical conditions in general. 

The researchers found that compared to controls, people with synesthesia were more likely to have relatives with synesthesia. In addition, they say, “People with three or more types of synesthesia were more likely (compared to synesthetes with fewer types) to have synesthetic relatives and to report autism in themselves.” Finally, they say, “People with two or more types of synesthesia (compared to synesthetes with only one type) were more likely to report familial autism.” 

They conclude, “The results suggest a shared genetic predisposition between synesthesia and autism, and more extreme synesthetes may tend to hail from more neurodiverse families.”


Citations

“Familial aggregation of synaesthesia with autism (but not schizophrenia),” Max Nugent and Jamie Ward, Cognitive Neuropsychiatry, July 7, 2022 (free online). Address: Jamie Ward, School of Psychology University of Sussex, Falmer, Brighton, BN1 9QH, UK, [email protected].