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Link found between synaesthesia and schizophrenia

Grapheme-coloured synaesthesia is a condition where people associate letters and numbers with specific colours. Researchers found this type of synaesthesia to share some of its biology with schizophrenia.

Pile of Different Coloured Letters

Grapheme-coloured synaesthesia is the most common form of synaesthesia. It's estimated that 86% of people with synaesthesia will fall into this group. Researchers at the Max Planck Institute, in the Netherlands, wanted to see if there is a link between synaesthesia and other mental disorders of the nervous system.

To understand the link, they invited volunteers with synaesthesia from Generation Scotland, the Netherlands, Russia,  Amsterdam and the rest of the UK to take part. Healthy volunteers from Generation Scotland and the BIG study, in the Netherlands, were also invited to take part. This allowed healthy individuals to be compared with those affected by synaesthesia.

All volunteers were asked to complete an online questionnaire. If the questionnaire showed the volunteer had synaesthesia they were invited to provide a saliva sample for DNA testing. In the case of Generation Scotland and BIG volunteers, the samples were already available. Samples of healthy Generation Scotland and BIG volunteers were also studied.

The study looked to see if there were any links between either autism or schizophrenia and grapheme-coloured synaesthesia. It was found that the chance of developing schizophrenia was higher in volunteers with grapheme-coloured synaesthesia than those without it. No link was found between autism and grapheme-coloured synaesthesia.

This study has helped researchers to understand how mental conditions work and interact. Though the results found weren't precise measures, they support the claim for more research into synaesthesia and its connection with other traits.

Thanks to these researchers we're beginning to paint a picture of the little known condition of synaesthesia. We'd also like to thank all of the volunteers who supported this study. 

If you'd like to read more, you can find the published article below:

Bridging senses: novel insights from synaesthesia