Efficacy of porcine secretin in children with autism and pervasive developmental disorder.

Saville et al. (2002) gave one IV shot of porcine secretin to children with autism or PDD. They split the kids into two groups: those with chronic diarrhea and those with no gut trouble. Then they watched who improved.

It was a blind RCT. Families did not know if the child got drug or salt water. Staff tracked problem behaviors after the single dose.

Only the kids with chronic diarrhea acted better after secretin. Their irritability and repetitive actions dropped. Children without GI signs looked the same on drug or placebo.

So the same medicine helped one slice of the autism spectrum and did nothing for the rest.

Dawson et al. (2000) tested the same single secretin dose two years earlier. They saw no change in any child. The key difference: G et al. did not sort by GI status. When you ignore tummy problems, the benefit vanishes.

Bottema-Beutel et al. (2023) later showed that GI pain and internalizing symptoms fuel each other in ASD youth. This loop gives a reason why fixing gut signals might calm behavior.

Karagözlü et al. (2022) found that kids with worse autism and worse GI issues also show high zonulin, a gut-leak marker. The pattern supports the idea that GI-positive autistic children form a biologically distinct group.

Before you trial any gut-based treatment, ask about diarrhea, constipation, or pain. If GI symptoms are absent, secretin is unlikely to help. Use a simple parent GI checklist first. Save time, money, and false hope.