Naltrexone is a medication that blocks the effects of drugs known as opioids. It competes with these drugs for opioid receptors in the brain. For additional information, also see our section on Opioid Excess Theories.

Dr. Cazzullo and colleagues at the University of Milan assessed the clinical and biological effects of high-dose, long-term Naltrexone (NTX) treatment in 11 children (3-11 years), who had been diagnosed as autistic. The drug was given following an open design, for 12 weeks. Beta-Endorphin (beta-END) was assayed in peripheral blood mononuclear cells after 1 and 3 months of treatment, and 6 months after the completion of the course.

Baseline beta-END levels were higher than in healthy age-matched controls. In seven patients treatment reduced beta-END, whose levels rose in four children. Autistic symptoms were considerably attenuated in all cases, with functional improvements involving several areas. There was a close correlation between the reduction in beta-END levels and the decrease of social withdrawal, and an evident--though weak--correlation between increases in beta-END and decreases in stereotypy and abnormal speech. Both effects persisted after treatment stopped.

Reference:

Cazzullo AG, Musetti MC, Musetti L, Bajo S, Sacerdote P, Panerai A. Beta-endorphin levels in peripheral blood mononuclear cells and long-term naltrexone treatment in autistic children. Eur Neuropsychopharmacol 1999 Jun;9(4):361-6.