Stuttering is both common (more than 70 million people worldwide, and 3 million in the U.S., deal with it at some point) and an exceedingly frustrating experience: You absolutely know what you want to say, but can't quite make it happen. Once thought to be an entirely psychological issue, as this new DNews video explains, researchers are beginning to understand more about the biological basis of stuttering. In a new study , published in a recent issue of Human Brain Mapping, researchers looked at the brains of 62 participants. Of those, 26 had stuttering and 36 did not. The results of the study showed that, compared to those without stuttering, participants with stuttering had lower blood flow level in an area of the brain associated with language. And those with more severe stuttering showed an even greater reduction in blood flow in that area. In particular, this area is involved in producing speech, which suggests that reduced blood flow here may cause or exacerbate a speech disorder like stuttering. To learn more about how this could cause stuttering — and why stuttering isn't anything to ashamed of — check out the video below.