Stuttering is an interruption of the normal flow of speech, which takes on many different patterns. Commonly, it involves either saying a string of repeated sounds or making abnormal pauses during speech.
In early childhood, stuttering is sometimes part of normal speech development. In fact, about 5% of all young children go through a brief period of stuttering when they are learning to talk. Stuttering typically is first noticed between the ages of 2 and 5. It usually goes away on its own within a matter of months. In a small number of children (around 1%), stuttering continues and may get worse. Boys are more likely to stutter than girls.
Researchers still are trying to determine why stuttering occurs. It runs in families, and genetic (inherited) factors probably play a larger part than previously recognized.
Some studies suggest the problem may be due to subtle changes in the brain pathways that process speech and language. Emotional factors may make the stuttering more pronounced but are not the cause.
After age 10, it is unusual for someone to begin stuttering if he or she has never stuttered before. In rare cases, stuttering can develop after a stroke or brain injury, or rarely as a side effect of some drugs, especially those used to treat seizures or severe psychiatric illness.