[7] Like other atypical antipsychotics, risperidone has also been used off-label for the treatment of anxiety disorders, such as
obsessive-
compulsive disorder, severe, treatment-resistant depression with or without psychotic features, Tourette syndrome, disruptive behavior disorders in children." Wikipedia
And I am surprised that a 4 year old is being medicated - but I don't know what the symptoms are. What kind of a doctor are you seeing?