Low-dose naltrexone effects on plasma chemistries and clinical symptoms in autism: a double-blind, placebo-controlled study.

Bouvard MP et al. Psychiatry Res. 1995 Oct 16;58(3):191-201.

The effect of month-long naltrexone (NTX) treatment at a daily oral
dose of 0.5 mg/kg/day was contrasted with placebo (PLC) in a
double-blind study with conjoint clinical and biochemical
evaluations of therapeutic effects. Modest clinical benefits were
achieved with both PLC and NTX, with marginally better overall
results following NTX, and degree of improvement appeared to be
related to plasma chemical profiles. Massively elevated levels of
beta-endorphin were observed in all children with assays using
C-terminal antibody but not with an N-terminal antibody assay. In
addition, 70% of the children exhibited abnormally low levels of
adrenocorticotropic hormone, and smaller subsets exhibited elevated
norepinephrine (60%), arginine-vasopressin (50%), and serotonin
(20%). The best clinical responders exhibited the clearest
normalization of the elevated plasma chemistries, especially in
C-terminal-beta-endorphin and serotonin. There was some evidence of
therapeutic carry-over effects in both clinical and biochemical
measures in those children who received NTX before PLC. The results
suggest that NTX only benefits a subgroup of autistic children, who
may be identified by the presence of certain plasma abnormalities.
These results suggest a possible linkage between abnormal plasma
chemistries, especially those related to the pro-opiomelanocortin
system, and autistic symptoms.

PMID: 8570775