The most common form of stuttering is thought to be developmental, that is, it is occurring in children who are in the process of developing speech and language. This relaxed type of stuttering is felt to occur when a child's speech and language abilities are unable to meet his or her verbal demands. Stuttering happens when the child searches for the correct word. Developmental stuttering is usually outgrown. Another common form of stuttering is neurogenic.
Neurogenic disorders arise from signal problems between the brain and nerves or muscles.
In neurogenic stuttering, the brain is unable to coordinate adequately the different components of the speech mechanism. Neurogenic stuttering may also occur following a stroke or other type of brain injury. Other forms of stuttering are classified as psychogenic or originating in the mind or mental activity of the brain such as thought and reasoning. Whereas at one time the major cause of stuttering was thought to be psychogenic, this type of stuttering is now known to account for only a minority of the individuals who stutter. Although individuals who stutter may develop emotional problems such as fear of meeting new people or speaking on the telephone, these problems often result from stuttering rather than causing the stuttering.