New York, Nov 28 (IANS): US researchers have identified neuro-metabolite alterations across the brain that linked stuttering to changes in brain circuits that control speech production and circuits that support attention and emotion.

Stuttering is a speech disorder in which the flow of speech is disrupted by involuntary repetitions and prolongations of sounds and syllables.

The study found that affected brain regions included major nodes of the speech-production network -- associated with the regulation of motor activity, the default-mode network -- involved in the regulation of attention -- and the emotional-memory network -- responsible for regulating emotion.

Attention-regulating portions of the brain are related to control circuits that are important in governing behaviour, the researchers said. 

"People with changes here are more likely to stutter and have more severe stuttering. And emotions like anxiety and stress also tend to make stuttering worse, likely because this network interacts with language and attention control circuits," said lead author Bradley S. Peterson, Director at Children's Hospital Los Angeles (CHLA) in the US. 

For the study, the scientists performed proton shift imaging of the brain in 47 children and 47 adults, both with and without stuttering.

The results confirmed that disturbances in neuronal or membrane metabolism contribute to the development of stuttering.

The study was published online in the Journal of the American Medical Association (JAMA).