Definition of Stuttering:

Stuttering is a speech disorder that involves involuntary hesitation, repetition ("ca-ca-ca-can"), or prolongations ("llllllike") while speaking.

Causes, incidence, and risk factors:

About 5% of children aged 2 - 5 go through a short period of stuttering, but this phase is very brief. For a small percentage (less than 1%), the stuttering progresses from simple repetition of consonants to repetition of words and phrases. Later, vocal spasms develop with a forced, almost explosive sound to the speech.

Stuttering tends to run in families, but it is unclear to what extent genetic factors are important. There is also evidence that stuttering may be associated with some neurological events, such as stroke or traumatic brain injuries. Psychological components tend to make the symptoms worse or better within each case.

Stuttering is rarely considered a psychological problem. Stressful social situations and anxiety, however, can make symptoms worse. Surprisingly, people with significant speech difficulty often don't stutter when singing or when they are alone talking to themselves. Stuttering tends to persist into adulthood more frequently in boys than in girls.