Opioid-immune interactions in autism: behavioural and immunological assessment during a double-blind treatment with naltrexone.
The emerging concept of opioid peptides as a new class of chemical messengers of the neuroimmune axis and the presence of a number of immunological abnormalities in infantile autism prompted us to correlate biological (hormonal and immunological) determinations and behavioural performances during treatment with the potent opiate antagonist, naltrexone (NAL). Twelve autistic patients ranging from 7 to 15 years, diagnosed according to DSM-III-R, entered a double-blind crossover study with NAL at the doses of 0.5, 1.0 and 1.5 mg/kg every 48 hours. The behavioural evaluation was conducted using the specific BSE and CARS rating scales NAL treatment produced a significant reduction of the autistic symptomatology in seven ("responders") out of 12 children. The behavioural improvement was accompanied by alterations in the distribution of the major lymphocyte subsets, with a significant increase of the T-helper-inducers (CD4+CD8-) and a significant reduction of the T-cytotoxic-suppressor (CD4-CD8+) resulting in a normalization of the CD4/CD8 ratio. Changes in natural killer cells and activity were inversely related to plasma beta-endorphin levels. It is suggested that the mechanisms underlying opioid-immune interactions are altered in this population of autistic children and that an immunological screening may have prognostic value for the pharmacological therapy with opiate antagonists.