“…Many of the studies highlighted different dimensions to the question and addressed previous criticisms: nine studies used porcine secretin (3)(4)(5)(6)(7)(11)(12)(13)15), five examined the human synthetic form (2,8,9,14,15), nine studies used cross-over designs (3,5,(7)(8)(9)(10)(11)14,15), and multiple doses were given in two studies (12,14). Several studies examined possible subgroup responders; patients with gastrointestinal symptoms (5)(6)(7)9,12,15), different degrees of autism severity (7,8,12,13,15), and those for whom other medical therapies were allowed (3,6,8,(10)(11)(12) or excluded (15).…”