Elevated iron concentration in putamen and cortical speech motor network in developmental stuttering.

Abstract

Theoretical accounts of developmental stuttering implicate dysfunctional cortico-striatalthalamo-cortical motor loops through the putamen. Analysis of conventional MRI brain scans in people who stutter has failed to yield strong support for this theory in terms of reliable differences in the structure or function of the basal ganglia, however. Here, we performed quantitative mapping of brain tissue, which can be used to measure iron content alongside markers sensitive to myelin and thereby offers particular sensitivity to the measurement of ironrich structures such as the basal ganglia. Analysis of these quantitative maps in 41 men and women who stutter and 32 matched controls revealed significant group differences in maps of R2*, indicative of higher iron content in people who stutter than controls in the left putamen and in left hemisphere cortical regions important for speech motor control. Higher iron levels in brain tissue in people who stutter could reflect elevated dopamine levels or lysosomal dysfunction, both of which are implicated in stuttering. This study represents the first use of these quantitative measures in developmental stuttering and provides new evidence of microstructural differences in the basal ganglia and connected frontal cortical regions.