European perspectives on hyperkinetic disorder

The impending globalization of ADHD: notes on the expansion and growth of a medicalized disorder

Attention Deficit Hyperactivity Disorder (ADHD) has been medicalized in the United States since the 1960s. Primarily used in North America until the 1990s, ADHD diagnosis and treatment have increasingly been applied internationally. After documenting the expansion of ADHD in a global context, this paper presents five brief international examples examining ADHD usage and expansion: the United Kingdom, Germany, France, Italy and Brazil. We then identify and describe several vehicles that facilitate the migration of the ADHD diagnosis: the transnational pharmaceutical industry; the influence of western psychiatry; moving from ICD to DSM diagnostic criteria; the role of the Internet including the related advent of easily accessible online screening checklists; and advocacy groups. Finally, we discuss what this globalization of a diagnosis reflects about the potential global medicalization of other conditions.

A comparison of North American versus non-North American ADHD study populations

Few large, prospective clinical studies in Europe have assessed the validity and applicability of research methods used to study ADHD in North America. To assess comparability of study populations, we examined baseline patient characteristics from a group of North American studies against those of a large European/African/Australian study. All studies used identical diagnostic assessments and inclusion criteria, with ADHD diagnosis and the presence of comorbid psychiatric conditions confirmed using the KSADS-PL. Raters were trained and assessed to ensure uniform diagnostic and symptom severity rating standards. Six hundred and four patients (mean age = 10.2 years) enrolled in the non-North American study, and 665 patients (mean age = 10.4 years) enrolled in the North American study. The proportion of girls was higher in the North American studies (29.2% vs. 10.4%, p < 0.001). In both groups, most patients had a positive family history of ADHD and previous stimulant treatment. Fewer had the inattentive subtype of ADHD, and mean severity was slightly higher in the non-North American study. Results demonstrate that, when a uniform set of rigorous, standardized diagnostic criteria are used by skilled clinicians, the patient populations identified are generally similar. This supports the practice of generalizing results from treatment studies across geographies.

Relapse prevention in pediatric patients with ADHD treated with atomoxetine: a randomized, double-blind, placebo-controlled study

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) is typically treated over extended periods; however, few placebo-controlled, long-term studies of efficacy have been reported.

METHOD

In a global multicenter study, children and adolescents who responded to an initial 12-week, open-label period of treatment with atomoxetine, a nonstimulant treatment for ADHD, were randomized to continued atomoxetine treatment or placebo for 9 months under double-blind conditions.

RESULTS

A total of 416 patients completed acute atomoxetine treatment and were randomized. At end point, atomoxetine was superior to placebo in preventing relapse defined as a return to 90% of baseline symptom severity (proportion relapsing: atomoxetine 65 of 292 [22.3%], placebo 47 of 124 [37.9%], p =.002). The proportion of patients with a 50% worsening in symptoms post-randomization was also lower on atomoxetine (atomoxetine 83 of 292 [28.4%], placebo 59 of 124 [47.6%], p <.001). Compared with patients in the placebo group, atomoxetine-treated patients had superior psychosocial functioning at end point. Discontinuations for adverse events were low in both groups, and tolerability was similar to that observed in acute treatment trials.

CONCLUSIONS

In patients who responded favorably to 12 weeks of initial treatment, atomoxetine was superior to placebo in maintaining response for the ensuing 9 months. This result supports the value of maintenance treatment with atomoxetine in patients with ADHD who respond to initial treatment.

A quantitative cytochrome oxidase mapping study, cross-regional and neurobehavioural correlations in the anterior forebrain of an animal model of Attention Deficit Hyperactivity Disorder

The aim of this study was to trace by molecular imaging techniques the neural substrates of attention deficit hyperactivity disorder (ADHD) using the spontaneously hypertensive rat (SHR) as animal model. Adult SHR and Wistar-Kyoto (WKY) controls were used throughout this study. In experiment 1, naive male SHR and WKY were used, whereas in experiment 2 SHR and WKY rats of both genders were trained on a multiple fixed interval (FI (120 s for water, 5-min extinction)) paradigm and sacrificed 6 months later. In both experiments coronal sections of the anterior forebrain were processed for quantitative cytochrome oxidase (COase) histochemistry by the method of Gonzalez-Lima. Optical density values were transformed into actual enzyme activity units by using tissue-calibrated standards. In experiment 1, non-trained male rats of the SHR line showed lower COase activity in the medial and lateral prefrontal cortices, compared with WKY controls. In experiment 2, there was a line x treatment interaction effect in the pole of the nucleus accumbens (ACB). Regional correlative analyses revealed that: (i) under basal conditions, SHR are more synchronized than WKY rats in the COase level of different brain regions; and (ii) the training desynchronizes COase activity in the WKY, further synchronizes it and increases the cross-talk between hemispheres in male SHR only. Neurobehavioral covariations between behavioural scores and metabolic capacity in the medial and lateral prefrontal/frontal cortices, the caudate-putamen complex (CPU), the pole, core, and shell of the accumbal complex (ACB), and the ventral pallidum (VP), indicated that, in the WKY rats, the frequency of lever pressing covaried positively with the COase activity in the CPU, whereas in the SHR covaried with both medial and lateral prefrontal/frontal cortices. The bursts of activity during the 1-1.33-s segment was positively correlated, in the WKY rats only, with the core and shell of the ACB, and with the VP. Finally, the correlative profiles showed significant gender differences with effects in male SHR only. Thus, the results lend support to the involvement of the cortico-striato-pallidal system in ADHD.

Reduced transduction mechanisms in the anterior accumbal interface of an animal model of Attention-Deficit Hyperactivity Disorder

The aim of this study was to map the neural substrates of attention-deficit hyperactivity disorder (ADHD) in the spontaneously hypertensive rat (SHR), which is thought to be a model for ADHD. To this aim, the Ca2+/calmodulin-dependent protein kinase II (CaMKII) and transcription factors (TF) were used as markers. The focus of interest was the nucleus accumbens complex (ACB) which is thought to be an interface between limbic and motor systems. Juvenile, male rats of the SHR line and Wistar-Kyoto (WKY) controls were perfused and the brains processed for immunocytochemistry for CaMKII and the TF peptides of the FOS, JUN-B and ZIF-268 families. The results revealed that: (i) in both groups there were more CaMKII-positive neurones in the shell than in the core of the ACB; (ii) SHR had a reduced number of CaMKII-positive elements in anterior portions of the shell; and (iii) SHR had a lower expression of peptide products of the FOS family (c-FOS, in particular) and ZIF-268. In addition, there was a lower expression of c-FOS and zif-268 in the core of the ACB in the SHR. In contrast, there was an increased basal level of JUN-B in the core of the ACB of SHR. The reduced number of CaMKII and TF-positive elements in the most rostral portions of the accumbal complex of SHR, associated to the higher number of binding sites for the DA D-1/D-5 subtype, appears as a discrete alteration in the prosomeric development of the anterior basal forebrain and could be the key to the understanding of ADHD.

Differential distribution, affinity and plasticity of dopamine D-1 and D-2 receptors in the target sites of the mesolimbic system in an animal model of ADHD

The distribution of dopamine (DA) D-1 and D-2 receptors has been studied by autoradiography in the anterior forebrain of the pre-hypertensive spontaneously hypertensive rat (SHR) as an animal model of attention-deficit hyperactivity disorder (ADHD) in children. Juvenile male SHR and Wistar Kyoto (WKY) controls were given either vehicle or the DA re-uptake blocker methylphenidate (MP; 3 mg/kg, i.p.), daily during a 2-week period. A saturation analysis for the D-1 receptor subfamily was carried out with 0.1-5.0 nM of [3H]SCH23390 and two competition studies for the D-2 receptor subfamily with 4 nM of [3H]raclopride or 5 nM of [3H]quinpirole were carried out with unlabelled spiperone and 7-OH-DPAT as unlabelled displacers on cryostat coronal sections of the anterior forebrain. Quantitative receptor autoradiography and computer-assisted image analysis with reference to co-exposed 3H-microscale standards showed in vehicle-treated SHR higher density of DA D-1/D-5 receptor subtypes in the caudate-putamen (CPU), the nucleus accumbens (ACB) core and shell and the olfactory tubercle (OT), which was associated to a lower affinity. MP treatment normalised the DA D-1/D-5 receptors by decreasing the number of binding sites and increasing the affinity to control level. In addition, MP treatment 'down-regulated' DA D-2/D-4 subtypes in the CPU, ACB and OT, and 'up-regulated' mostly D-3 subtype in CPU, ACB, OT in both rat lines and in the globus pallidus, ventral pallidum and lateral septum in WKY rats only. In contrast, D-3 receptors were 'down-regulated' in the islands of Calleja in both rat lines. Moreover, regional cross-correlative analyses revealed a modulatory influence of DA receptors in the cross-talk within the anterior forebrain, which was altered in the SHR. Thus, the differential distribution and regulation of DA receptor subtypes following DA re-uptake blocker as well as the different regional cross-talk in the target sites of nigrostriatal and mesolimbic DA systems lend support to the DA hypothesis of ADHD in children.

Differential expression of transcription factors in the accumbens of an animal model of ADHD

Transcription factors have been used as neuronal markers in the nucleus accumbens (ACB) of male juvenile spontaneously hypertensive rats (SHR), an animal model of attention-deficit hyperactivity disorder (ADHD), to trace putative neural substrates. In SHR, immunocytochemistry and PC-assisted image analysis showed lower expression of pan-fos, c-fos, zif/268 in the shell, and the c-fos and zif/268 in the core, with an increased level of Jun-B in the core. The differential lower basal expression of transcription factors in the ACB of an animal model of ADHD implies a reduced number of modules and might represent a neural substrate of the attention deficits seen in SHR and children with ADHD at low motivational levels.

ADHD, DAMP and other neurodevelopmental/psychiatric disorders in 6-year-old children: epidemiology and co-morbidity

A total population of 589 6-year-old children were screened for neurodevelopmental/neuropsychiatric disorders by questionnaires to parents and preschool teachers, and by examination of motor abilities at the Child Health Center. Fifty screen-positive and fifty screen-negative children were assigned for complete neuropsychiatric assessment comprising a detailed history, psychiatric and neurodevelopmental assessment, neuropsychological examination and speech/language evaluation. Comprehensive diagnoses were made on the basis of all the available information. In the total population, 63 children (10.7%) with disorders were identified, 10 of whom had a diagnosis established before the study. The prevalence rates for deficits in attention, motor control and perception (DAMP) were 5.3 to 6.9%, for attention deficit hyperactivity disorder (ADHD) they were 2.4 to 4.0% and for mental retardation, 2.5%. Co-morbidity was established for ADHD on the one hand and DAMP, mental retardation and Tourette syndrome on the other. The findings suggest the need for a school entrant screening examination for the types of problems examined in this study.

Symptoms of attention-deficit hyperactivity disorder in an Italian school sample: findings of a pilot study

OBJECTIVE

The objective of this study was to complete a teacher questionnaire on a sample of children (N = 232) in nine fourth grade classes in schools in two regions of central Italy to assess the frequency of occurrence of symptoms of attention-deficit hyperactivity disorder (ADHD) and the rates of probable cases in the sample.

METHOD

Each ADHD symptom was rated by the teacher as either absent (0), sometimes present (1) or frequently present (2).

RESULTS

Of the children 3.9% had eight or more DSM-III-R Criterion A symptoms of ADHD scored at a "frequent" level (score of 2) and were considered to be "likely cases" of ADHD; an additional 6.9% did not meet this threshold but had a total score of 16 or more on the scale and were considered to be "possible cases."

CONCLUSIONS

The findings suggest the need for more systematic epidemiological investigations to evaluate the true prevalence of the syndrome and its risk factors in the Italian population.