Plasma growth hormone response to oral l-dopa in infantile autism.
About one-third of autistic kids show a blunted growth-hormone jump after L-dopa, hinting at a dopamine-linked subtype.
01Research in Context
What this study did
Doctors gave autistic kids a single dose of L-dopa. They drew blood before and after.
The team watched how much growth hormone the pituitary squirted out. A weak reply might flag a dopamine glitch in the brain.
What they found
Roughly one in three children showed a flat-line hormone jump. The rest reacted like typical kids.
The low responders may share a subtle hypothalamic dopamine problem.
How this fits with other research
Durand et al. (1990) repeated the same L-dopa test but added a control group. They saw normal peak levels, just shifted timing. The two papers look opposite until you check the yardstick: I et al. scored height of the spike, M et al. scored when it arrived.
Lord et al. (1986) found high dopamine-beta-hydroxylase in less-delayed autistic kids. That blood enzyme fits the idea of catecholamine oddballs inside the spectrum.
Jones et al. (1992) flipped dopamine activity with two drugs. Kids who got the dopamine blocker improved core autism signs, while the dopamine booster helped only hyperactivity. The trial shows changing dopamine can tweak behavior, backing the probe studies.
Why it matters
You can’t test growth hormone in clinic, but you can watch for uneven response to rewards or meds. If a child perks up on risperidone yet stays hyper on stimulants, think dopamine subgroup. Track side-effects closely and share endocrine clues with the pediatrician.
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02At a glance
03Original abstract
In order to assess further the occurrence of hypothalamic dysfunction in infantile autism and its possible relationship to dopaminergic abnormalities, the l-dopa provocative test was performed in 22 patients fulfilling DSM-III criteria for this disorder. The results indicate a high incidence (at least 30%) of blunted plasma growth hormone (GH) responses following oral administration of l-dopa in this sample. These data suggest an alteration of hypothalamic dopamine receptor sensitivity in the patients with blunted responses. Thus, a subgroup of autistic patients within a descriptively homogeneous diagnostic category shows evidence of hypothalamic dysregulation and dopaminergic abnormalities.
Journal of autism and developmental disorders, 1985 · doi:10.1007/BF01531606