Supporters of therapy as a cause of DID suggest that a small number of clinicians diagnosing a disproportionate number of cases would provide evidence for their position though it has also been claimed that higher rates of diagnosis in specific countries like the United States may be due to greater awareness of DID. Lower rates in other countries may be due to artificially low recognition of the diagnosis. However, false memory syndrome per se is not regarded by mental health experts as a valid diagnosis, and has been described as "a non-psychological term originated by a private foundation whose stated purpose is to support accused parents," and critics argue that the concept has no empirical support, and further describe the False Memory Syndrome Foundation as an advocacy group that has distorted and misrepresented memory research. Children
The rarity of DID diagnosis in children is cited as a reason to doubt the validity of DID, and proponents of both etiologies believe that the discovery of DID in a child who had never undergone treatment would critically undermine the SCM. Conversely, if children are found to develop DID only after undergoing treatment it would challenge the traumagenic model. As of 2011, approximately 250 cases of DID in children have been identified, though the data does not offer unequivocal support for either theory.
Their claim is evinced by the fact that only 5%–10% of people receiving treatment worsen in their symptoms.Psychiatrists August Piper and Harold Merskey have challenged the trauma hypothesis, arguing that correlation does not imply causation – the fact that people with DID report childhood trauma does not mean trauma causes DID – and point to the rareness of the diagnosis before 1980 as well as a failure to find DID as an outcome in longitudinal studies of traumatized children. They assert that DID cannot be accurately diagnosed because of vague and unclear diagnostic criteria in the DSM and undefined concepts such as "personality state" and "identities", and question the evidence for childhood abuse beyond self-reports, the lack of definition of what would indicate a threshold of abuse sufficient to induce DID and the extremely small number of cases of children diagnosed with DID despite an average age of appearance of the first alter of three years. Psychiatrist Colin Ross disagrees with Piper and Merskeys conclusion that DID cannot be accurately diagnosed, pointing to internal consistency between different structured dissociative disorder interviews (including the Dissociative Experiences Scale, Dissociative Disorders Interview Schedule and Structured Clinical Interview for Dissociative Disorders) that are in the internal validity range of widely accepted mental illnesses such as schizophrenia and major depressive disorder. In his opinion, Piper and Merskey are setting the standard of proof higher than they are for other diagnoses.