Acute and chronic clonidine treatment in Tourette's syndrome: a preliminary report on clinical response and effect on plasma and urinary catecholamine metabolites, growth hormone, and blood pressure

Growth hormone response to guanfacine in boys with attention deficit hyperactivity disorder: a preliminary study

OBJECTIVE

This preliminary study evaluated a method for assessing central noradrenergic function in children via the growth hormone response to a single dose of the alpha-2 adrenergic receptor agonist guanfacine and examined whether this measure distinguishes between attention deficit hyperactivity disorder (ADHD) boys with and without reading disabilities (RD).

METHODS

Plasma growth hormone was assessed before and after the oral administration of guanfacine and placebo in boys with ADHD who were divided into subgroups based on the presence (n = 3) or absence (n = 5) of RD.

RESULTS

Guanfacine and placebo conditions did not differ at baseline, but peak growth hormone was significantly higher following guanfacine. The increase in growth hormone following guanfacine was significantly greater in boys without RD as compared to those with RD, with no overlap between the groups.

CONCLUSIONS

Consistent with findings using peripheral measures of noradrenergic function, these preliminary data suggest that ADHD boys with and without RD may differ in central noradrenergic function.

Psychophysiological aspects of Tourette's syndrome

Tourette's syndrome (TS), once considered a rare disorder, has been investigated extensively in the last two decades. It is inherited, usually beginning in childhood, and waxes and wanes, usually decreasing in frequency and severity in adolescence and early adulthood. Pharmacotherapy is the usual treatment approach, reducing frequency and severity of symptoms, but it is not a cure and often has side effects. Psychological help for people with TS and their families may be needed for this complex disorder.

Neurochemical and some related psychopharmacological aspects of Tourette's syndrome: an update

Neurochemical investigations of Tourette's syndrome (TS) suggest that the symptoms of this disorder may be the result of an imbalance among several neurotransmitter and/or neuromodulator systems. Neurochemicals which have been studied included: catecholamines; acetylcholine; tryptophan and its metabolites; the amino acids γ-aminobutyric acid (GABA), glutamate, phenylalanine and p-tyrosine; trace amines; opioid peptides; cyclic AMP and androgenic hormones. A suitable animal model of TS would do much to advance our understanding of this disorder, and there are some interesting recent developments in this regard.

Evaluation of the reported association of obsessive-compulsive symptoms or disorder with Tourette's disorder

This review evaluates the evidence reporting an association of obsessive-compulsive symptoms (OCS) and obsessive-compulsive disorder (OCD) with Tourette's syndrome or disorder (TS). Published reports in the literature describing a relationship between OCS-OCD and TS provided the data for the review. The methodological adequacy of the studies are discussed and rated on five criteria: adequacy of the experimental sample, presence and adequacy of the control sample, whether tics are defined as OCS-OCD, whether blind procedures are used to diagnose OCS-OCD in subjects and controls, and evidence for the reliability and validity of OCS-OCD measures. Although there are considerable clinical indications suggesting an association of OCS-OCD with TS and chronic motor tic disorder (CMT), and a possible overlap between OSC-OCD and TS, our evaluation of the evidence does not provide adequate support for an association between these disorders. To meaningfully evaluate the possible relationship between OCS-OCD and TS requires development of specific criteria for classification of OCS-OCD-TS symptoms, use of adequate experimental and control samples, blind evaluation, reliable and valid measures of OCS-OCD-TS, and appropriate statistical analysis. If such studies are performed, it is possible that the strong relationship reported between OCS-OCD and TS is more likely to be artifact than fact, and recent bandwagon effect rather than the latest breakthrough.

Urinary excretion of metabolites of norepinephrine in Tourette's syndrome

Urinary excretion of the norepinephrine metabolites 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) and normetanephrine (NMR) was measured in Tourette's Syndrome (TS) patients and in control subjects matched for age and education. The 24-h excretion (expressed per gram of creatinine) of total MHPG and of free and total (free + conjugated) NME was significantly lower in TS patients than in the normal subjects.

Transient exacerbation of tics in treatment of Tourette's syndrome with clonidine

An 11-year-old boy with a history of behavioral problems was admitted to the inpatient Child Development Program of St. Louis University Medical Center. A diagnosis of Tourette's syndrome was made, and when family objected to a trial of haloperidol for fear of tardive dyskinesia, clonidine was initiated. A temporary period of worsening of motor and phonic tics ensued, while dose adjustments were made. When a maintenance level was achieved, approximately 2 weeks after initiating treatment, remission of symptoms was observed.

Pediatric psychopharmacology

This article is a brief and selected overview of pediatric psychopharmacology, a field which links medicine, behavioural sciences, and neurosciences to child psychiatry. It will summarize current knowledge and recent advances related to the indications, effects, limitations and research issues of psychostimulants, antidepressants, antipsychotics, anxiolytics, anticonvulsants and diets used in the treatment of child and adolescent psychiatric disorders.

Neuropsychological correlates of urinary amine metabolites in Tourette's syndrome

The relationships between neuropsychological performance and urinary amine metabolite levels (HVA, 5-HIAA, MHPG) were examined in a sample of 27 medication-free patients with Tourette's Syndrome. Correlations with specific metabolites indicated neuropsychological deficit associated with higher levels of HVA and lower levels of 5-HIAA. Variables computed to express the interaction of the various neurotransmitter systems provided strong and consistent support for such interactions in the underlying mechanism of the neurobehavioral deficits observed in these patients. The implications of these findings and directions for future research were discussed.

Clonidine challenge testing of alpha-2-adrenoceptor function in man: the effects of mental illness and psychotropic medication

The clonidine challenge test is a means of assessing alpha-2-adrenoceptor sen sitivity in man. We review studies which have used this test to investigate central alpha-2- adrenoceptor changes in psychiatric illness, and to determine receptor changes after adminis tration and withdrawal of psychotropic treatments. Patients with severe depression show evidence of reduced alpha-2-adrenoceptor sensitivity, especially a reduced growth hormone response to clonidine. This may delineate a subgroup of patients with severe depressive illness from those with milder depression, and may even provide a trait marker for some depressed patients. Patients with panic disorder show evidence of subsensitivity to some and supersensitivity to other clonidine-induced responses. Other disorders, although less well investigated, may have abnormal test responses which may provide additional information about their cause and treatment. Changes in response after drug treatment have provided important information on the mode of action of antidepressants, and have suggested that noradrenergic function is altered by a variety of different antidepressants.

Effect of clonidine on platelet alpha 2-adrenoreceptors and plasma norepinephrine of children with Tourette syndrome

Clonidine, an alpha 2-adrenoreceptor agonist, is useful for treating some patients with Tourette syndrome, and it has been suggested that their noradrenergic receptors are 'subsensitive'. The authors measured plasma norepinephrine and specific binding of 3H-clonidine and 3H-yohimbine, an alpha 2-adrenoreceptor antagonist, to receptors on platelet membranes from children with Tourette syndrome. Before clonidine treatment, plasma norepinephrine, the maximum number of binding sites and the dissociation constants for both ligands were the same as for the controls. After two weeks of treatment there was little clinical improvement, but the number of binding sites for 3H-yohimbine decreased and plasma norepinephrine also decreased in four of the five patients. Over the next six months all five patients continued to improve clinically, but both indices of noradrenergic activity returned towards baseline values. The data suggest that clonidine's action may be independent of its prominent effects on alpha 2-adrenergic receptors and norepinephrine release.

Whole blood serotonin and tryptophan levels in Tourette's disorder: effects of acute and chronic clonidine treatment

Whole blood serotonin (WB5HT) and tryptophan (WBTRP) levels were studied in 20 patients (aged 8 to 45 years) with Tourette's disorder under medication-free baseline conditions and following acute and chronic clonidine treatment. Compared to 87 normal controls, Tourette's disorder patients had lower mean baseline WBTRP levels (mean +/- SEM: Tourette's, 5993 +/- 304 ng/ml vs. 6822 +/- 169 ng/ml; p less than .03). No significant differences in mean baseline WB5HT levels were found. Three hours after an acute dose of clonidine (2.5 - 5.1 micrograms/kg, p.o. at 9:00 A.M.), no mean differences were observed (baseline vs. post 3 hours) in WB5HT or WBTRP levels. However, following chronic treatment (greater than 3 weeks) with clonidine (3-8 micrograms/kg/day, p.o.), WB5HT levels were increased in 9 of 14 Tourette's disorder patients. The mean increases in WB5HT levels following chronic clonidine treatment were significant when WB5HT levels were expressed per 10(9) platelets. (mean +/- SEM: baseline, 471 +/- 45 ng/10(9) platelets vs. chronic, 697 +/- 82 ng/10(9) platelets, p = .02). No mean differences in WBTRP levels were observed after chronic clonidine treatment. These findings are discussed in light of a proposed intermediary role of 5HT systems in the mode of action of clonidine in the treatment of Tourette's disorder.

Possible change in noradrenergic receptor sensitivity following methylphenidate treatment: growth hormone and MHPG response to clonidine challenge in children with attention deficit disorder and hyperactivity

Growth hormone (GH) and 3-methoxy-4-hydroxyphenelethylene glycol (MHPG) response was measured hourly for 4 hours in 8 children with Attention Deficit Disorder with Hyperactivity (ADD+H) following an acute single-dose of clonidine. The clonidine challenge was repeated before, during, and one day after 12 weeks of treatment with methylphenidate (MPH). Before MPH treatment, the plasma growth hormone (GH) rose to 31.3 +/- 4.6 (Mean +/- SE) ng/ml; during MPH treatment, the GH peak was only 14.8 +/- 3.2 ng/ml; one day after discontinuation of MPH, GH rose to only 20.8 +/- 3.9 ng/ml. MHPG release was inhibited by clonidine in all treatment conditions but tended to be more decreased during MPH treatment. Some children with ADD+H may have hypersensitivity of the post-synaptic alpha-1 noradrenergic receptor which is diminished by MPH treatment. The extent to which these effects are pharmacological or represent a change in receptor sensitivity requires further study.