Plasma free MHPG and neuroendocrine responses to challenge doses of clonidine in Tourette's Syndrome: Preliminary report

Abstract

The metabolic response to clonidine was examined in a pilot study of several patients with Tourette's Syndrome (TS). Preliminary results in a small number of patients suggested hypotheses for further investigation. Plasma free MHPG was reduced in three clinically responsive patients following a challenge dose of clonidine or haloperidol. During maintenance treatment with clonidine, a challenge dose of clonidine continued to elicit a decrease in plasma free MHPG, and CSF free MHPG was reduced. On the other hand, a clinically non-responsive TS patient on maintenance clonidine failed to show this decrease in plasma free MHPG. Prolactin, TSH, cortisol, T 3, and thyroxine indices were not changed by clonidine administration to TS patients. There was a variable GH response to clonidine. Neuroendocrine responses of patients to single oral doses of clonidine may provide a useful method of differentiating subgroups of childhood neuropsychiatric patients.