The effects of fenfluramine (hydrochloride) on the behaviors of fifteen autistic children.
Fenfluramine lowered serotonin but failed to improve IQ, adaptive behavior, or play in autistic children—stick to behavioral interventions.
01Research in Context
What this study did
Doctors gave fifteen autistic children either fenfluramine or a placebo pill for eight weeks. They filmed free-play sessions and tested IQ and daily living skills before and after.
Fenfluramine lowers serotonin, a chemical thought to calm repetitive behaviors. The team wanted to see if less serotonin would also boost learning and play.
What they found
The drug did drop serotonin, but IQ, self-care, and play stayed flat. Videotapes actually showed slightly better play after placebo.
Side effects like tiredness showed up, yet no behavior gains appeared. The authors said fenfluramine is not worth using for autism.
How this fits with other research
Barthelemy et al. (1989) ran the same drug and design the same year. They tracked urine samples and found six of thirteen kids did improve. Their key point: only children who started with low dopamine markers got better, hinting the drug helps a small subgroup.
Aman et al. (1993) later tested fenfluramine in kids with intellectual disability plus ADHD and saw clear gains in attention. The drug can work, just not for autism.
Ratliff-Schaub et al. (2005) repeated the null theme with secretin, another failed autism pill. Together these studies show medications rarely beat placebo for core autism traits.
Why it matters
When parents ask about pills, you can show strong evidence that fenfluramine and similar serotonergic drugs do not help autism behaviors. Save your hours for teaching skills, not chasing blood levels. If a doctor later proposes a new serotonin drug, ask for data specific to autism, not just to other developmental disorders.
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02At a glance
03Original abstract
Fifteen autistic individuals were involved in an investigation using fenfluramine and placebo in a double-blind crossover design. Subjects were assessed using IQ tests, the Real Life Rating Scale (RLRS), the Adaptive Behavior Scale-School Edition (ABS-SE), and videotaped play data on 8 of 12 visits, including 2 follow-up visits. Serotonin level in platelet-poor plasma was assessed on all 12 visits. Serotonin levels decreased with the administration of fenfluramine, and increased with the reinstatement of placebo. Statistical tests revealed no significant differences on the IQ scores, the RLRS, or the ABS-SE for the drug versus the placebo conditions. Videotaped data favored the subjects while on placebo. Group and individual data were analyzed over time and indicated no significant improvements due to the drug. The implications of this research make it difficult to recommend fenfluramine as a treatment for autism.
Journal of autism and developmental disorders, 1989 · doi:10.1007/BF02212856