July 24, 2002 -- Children with developmental dyslexia may be missing a beat when it comes to detecting speech rhythms. Researchers say these difficulties may offer new clues about what causes dyslexia and lead to new treatments for the disorder.
Children with dyslexia have problems with reading, writing, spelling, math, and sometimes music that can't be explained by obvious reasons. The exact cause of the condition is unknown, but there are many possible theories.
Some previous research has suggested that dyslexia may be caused by an inability to perceive rapidly changing auditory stimuli. But the authors of a new study say that impairment may only play a secondary role and the bigger issue is an inability to follow rhythms in speech and other sounds.
In the study, Usha Goswami, professor of cognitive developmental psychology at the Institute of Child Health in London, and colleagues tested the auditory processing abilities of several groups of 11-year-olds, children who had been diagnosed as dyslexic, normal, and gifted readers.
Researchers found the dyslexic children were much less sensitive than the others in detecting rhythmic beats in nonspeech sounds (tones).
The ability to detect these rhythms was also linked to the child's reading and spelling ability across all three groups. The better the child was at detecting the rhythms, the more likely he or she was to be a better reader.
The study authors say beat detection may play an important role in processing speech at the most basic level -- the syllable. They argue that an inability to recognize or detect these basic speech patterns and rhythms among young children -- long before they are taught to read -- may be one of the major problems that leads to dyslexia in later years.
Researchers say more studies, preferably across different languages, to further test this hypothesis and suggest possible future interventions to treat dyslexia. Their study appears in the July 22 edition of the Proceedings of the National Academy of Sciences.
Dyslexia affects an estimated 10 million Americans. Although it cannot be prevented or cured, it can be managed with specialized teaching and support.