Opioid excess theory
The opioid excess theory is a theory which postulates that
Early years
This hypothesis was first proposed by Jaak Panksepp in a 1979 paper, in which he speculated that autism might be "an emotional disturbance arising from an upset in the opiate systems in the brain."[3] Kalle Reichelt then emerged as one of the leading advocates of this theory, publishing papers alleging that "the patterns of peptides and associated proteins from urinary samples [from people with autism] differ considerably from each other and from normal controls." In addition, Reichelt's research has concluded that autistic individuals have increased levels of these peptides in their cerebrospinal fluid.[4] Additionally, in a 1991 paper, Reichelt argued that gluten and casein may play a causative role in autism, as the incomplete digestion thereof may produce certain opioid peptides.[5] Thus, those, such as Paul Shattock, who advocate this theory also advocate the use of a gluten-free, casein-free diet as a treatment for autism.[citation needed]
Wakefield study
In 1998, a fraudulent paper by Andrew Wakefield was published in The Lancet presenting apparent evidence of a link between the MMR vaccine, gastrointestinal disease and autism. In this paper, which has since been retracted, Wakefield et al. speculated that food-derived peptides "may exert central-opioid effects, directly or through the formation of ligands with peptidase enzymes required for breakdown of endogenous central-nervous-system opioids, leading to disruption of normal neuroregulation and brain development by endogenous encephalins and endorphins."[6]
Later research
Reichelt has published a number of papers concluding that autistic children excrete higher levels of peptides in their urine,
Possible implications for treatment
Several double blind studies experimented with low dose opioid antagonists, such as naltrexone, for treatment of autism. A recent systematic review, published in 2014[16] showed statistically significant improvement in symptoms of irritability and hyperactivity in 77% of children treated with naltrexone. Core autism symptoms were unaffected. Side effects were mild and the drug was generally well tolerated. The number of children undergoing such therapy in the 10 analysed studies was only 128.
References
- PMID 18425890.
- ^ Special diets and autism
- S2CID 54373822.
- PMID 7010949.
- ^ Probable etiology and possible treatment of childhood autism
- S2CID 439791.
- .
- PMID 7708177.
- S2CID 46566945.
- S2CID 26253683.
- ^ "Social Dysfunction in Autism and Connection with Endogenous Opiads". www.macalester.edu. Archived from the original on 2003-09-24.
- S2CID 28604551.
- S2CID 38949901.
- PMID 18337276.
- .
- S2CID 11896817.