The Gut and Psychology Syndrome Diet (GAPS Diet) is an even more restrictive variant of the SCD, devised by a Russian neurologist. The diet is promoted with claims it can treat a wide variety of conditions including autism, schizophrenia and epilepsy. Like the SCD, claims of the diet's usefulness for children with autism are not supported by scientific studies. Harriet Hall has described the GAPS diet as "a mishmash of half-truths, pseudoscience, imagination, and untested claims", and Quackwatch includes the GAPS Diet in its "Index of questionable treatments".