The finding, by team of scientists from Cambridge University, suggests that while synesthesia only occurs in about 7 percent of the general population, nearly 1 in 5 people with autism experiences the condition.
 

"I have studied both autism and synesthesia for over 25 years and I had assumed that one had nothing to do with the other. These findings will re-focus research to examine common factors that drive brain development in these traditionally very separate conditions," said lead researcher Simon Baron-Cohen at the Autism Research Centre at Cambridge.

Special: Chocolate's 700 Year History of Healing
 

"An example is the mechanism 'apoptosis,' the natural pruning that occurs in early development, where we are programmed to lose many of our infant neural connections. In both autism and synesthesia apoptosis may not occur at the same rate, so that these connections are retained beyond infancy."
 

Synesthesia involves a "mixing of the senses" — seeing colors or experiencing unusual taste sensations when a sound or musical notes are heard.
 

For the new study, researchers tested 164 adults with autism and 97 adults without the condition. All volunteers were screened for synesthesia. About 31 people with autism also had synesthesia — nearly three times the rate of those without autism.
 

"People with autism report high levels of sensory hyper-sensitivity, " said Donielle Johnson, who helped carry out the research. "This new study goes one step further in identifying synesthesia as a sensory issue that has been overlooked in this population. This has major implications for educators and clinicians designing autism-friendly learning environments."