(1996) administered fluoxetine to 21 children for nine weeks and found that 76% of the children had reduced or no symptoms by the end of the experiment. This indicates that fluoxetine is an SSRI that is indeed helpful in treating selective mutism. History
In 1877, German physician Adolph Kussmaul described children who were able to speak normally but often refused to as having a disorder he named aphasia voluntaria. Although this is now an obsolete term, it was part of an early effort to describe the concept now called selective mutism. In 1980, a study by Torey Hayden identified what she called four "subtypes" of elective mutism (as it was called then), although this set of subtypes is not in current diagnostic use. These subtypes are no longer recognized, though "speech phobia" is sometimes used to describe a selectively mute person who appears not to have any symptoms of social anxiety. The Diagnostic and Statistical Manual of Mental Disorders (DSM), first published in 1952, first included selective mutism in its third edition, published in 1980. Selective mutism was described as "a continuous refusal to speak in almost all social situations" despite normal ability to speak. While "excessive shyness" and other anxiety-related traits were listed as associated features, predisposing factors included "maternal overprotection", "mental retardation", and trauma. Elective mutism in the third edition revised (DSM III-R) is described similarly to the third edition except for specifying that the disorder is not related to social phobia.
Some autistic people may be selectively mute due to anxiety in unfamiliar social situations. If mutism is entirely due to autism spectrum disorder, it cannot be diagnosed as selective mutism as stated in the last item on the list above. The former name elective mutism indicates a widespread misconception among psychologists that selective mute people choose to be silent in certain situations, while the truth is that they often wish to speak but are unable to do so. To reflect the involuntary nature of this disorder, the name was changed to selective mutism in 1994. The incidence of selective mutism is not certain. Due to the poor understanding of this condition by the general public, many cases are likely undiagnosed. Based on the number of reported cases, the figure is commonly estimated to be 1 in 1000, 0.1%. However, a 2002 study in The Journal of the American Academy of Child and Adolescent Psychiatry estimated the incidence to be 0.71%.