Though the exact cause of stuttering is not known, yet there are three leading theories that propose how stuttering develops. The learning theory proposes that stuttering is a learned behavior and that most normal children are occasionally disfluent when at the age at which speech and language develop. If a child is criticized or punished for this, he or she may develop anxiety about the disfluencies, causing increased stuttering and increased anxiety. Stuttering is a psychological problem-that stuttering is an underlying problem that can be treated with psychotherapy is suggested by the second theory. The third theory proposes that the cause of stuttering is organic, that neurological differences exist between the brains of those who stutter and those who don’t. Although the interference with speech is sometimes triggered by emotional or situational factors, stuttering is basically neurological and physiological – not psychological – in nature. In all other respects, persons who stutter are perfectly normal.
There is also some indication that genetic factors are involved in the development of stuttering and subsequent recovery, as shown by various studies done on families and twins. It is not known to what degree stuttering is dependent on genetic factors, on environmental factors, or on both. The most common type of stuttering (sometimes called developmental stuttering) usually develops of its own accord in childhood, most often between ages two and eight (although in rare cases it may begin much later). Roughly 4 to 5 per cent of people experience stuttering at some time during their childhood. While the majority become fluent by the time they reach adulthood, stuttering may continue to be a chronic, persistent problem for other stutterers. Stuttering is in short, thought to be a physical disorder and is not thought to be caused by psychological factors such as nervousness or stress, or parenting practices or the way parents communicate with their children when they are young.
In families stuttering tends to run, and it is generally accepted that this is because genetics is involved in the cause. However, the precise nature of the inheritance is unknown at present. Because stuttering occurs in families, speech researchers are inclined to say that stuttering has genetic roots. Recent advances in the field of human genetics allow scientists to identify the genes that cause any disorder which shows inheritance in families. The identification of “stuttering genes” is the subject of The Stuttering Family Research Project at the National Institutes of Health, a project which has identified over 350 families who can donate cheek samples to be analyzed for DNA. There is a small but growing pool of data which show that the brain shows certain focal abnormalities in persons who stutter. When the individual is speaking and appear within the premotor, motor, and auditory association areas of the cerebral cortex these abnormalities appear only Neuropharmacological attempts to control stuttering have been developed, but side effects of such medications have been numerous and unpleasant.
