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Blood serotonin concentrations and fenfluramine therapy in autistic children
Insights
Fenfluramine treatment in autistic children significantly decreased blood serotonin levels. While not improving general intelligence, it showed selective benefits in attention and language for high-functioning individuals.
Area of Science:
- Neuroscience
- Child Psychology
- Pharmacology
Background:
- Whole-blood serotonin concentrations were analyzed in autistic children and compared to neurodevelopmental control groups.
- Previous research suggests altered serotonin levels in autism spectrum disorder (ASD).
Purpose of the Study:
- To investigate whole-blood serotonin levels in autistic children compared to neurotypical and other developmental disorders.
- To evaluate the efficacy of fenfluramine in treating autistic children, focusing on behavioral and cognitive outcomes.
- To assess the relationship between fenfluramine treatment, blood serotonin levels, and clinical response.
Main Methods:
- Fluorometric measurement of whole-blood and platelet serotonin concentrations in autistic children, children with Down syndrome, and controls.
- A double-blind, placebo-controlled crossover study of fenfluramine in seven autistic boys over eight months.
- Assessment of auditory memory, receptive language skills, and general intelligence using psychometric measures.
Main Results:
- Autistic children and those with intellectual disabilities did not differ in blood serotonin levels from controls; children with Down syndrome had significantly lower levels.
- Fenfluramine administration led to a significant decrease in blood serotonin levels in all participants.
- Slight improvements in short-term auditory memory and receptive language were observed in high-functioning autistic children during fenfluramine treatment.
- No significant changes in global intelligence measures or significant adverse effects, except for weight loss in one child.
Conclusions:
- Fenfluramine may offer selective benefits for attention and cognitive functions in high-functioning autistic children.
- Blood serotonin levels can serve as an indicator of fenfluramine compliance but not necessarily clinical efficacy.
- Further research is warranted to explore fenfluramine's therapeutic potential in specific subgroups of autism spectrum disorder.
Abstract:
Whole-blood serotonin concentrations of 31 autistic children, aged 2 1/2 to 16 years, 10 non-autistic retarded children, and 18 children with Down syndrome were measured by a fluorometric method and compared with those of normal children of similar age range. No significant difference in the serotonin concentration per milliliter of whole blood or per 1000 platelets was found between groups for autistic, retarded, or normal children, but the values for those with Down syndrome were significantly lower. A double-blind cross-over study on the effect of fenfluramine versus placebo in seven autistic boys over a period of 8 months demonstrated a significant decrease in blood serotonin levels during the fenfluramine phase in all subjects. Slight improvements were found in short-term auditory memory and some measures of receptive language skills, particularly in children functioning at a high level. There was no significant change in global psychometric measurements of general intelligence during therapy. No adverse clinical effect was observed other than weight loss of 6% in one child. We conclude that fenfluramine may have some selective favorable effects on increasing attention in high-functioning autistic children. Blood serotonin concentration may be followed as an indication of drug compliance during fenfluramine therapy, but does not appear to reflect clinical efficacy.