Guidelines and algorithms for the use of methylphenidate in children with Attention-Deficit/ Hyperactivity Disorder

OBJECTIVE

To review published algorithms for guiding the use of methylphenidate (MPH) in the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD) in children and adolescents.

METHODS

A consensus roundtable of 12 experts was convened to review the evidence for the safety and efficacy of MPH in the treatment of ADHD, as well as the published algorithms and practice guidelines for using MPH. The experts reviewed the algorithms for practicality and acceptability by clinicians.

RESULTS

Algorithms that included MPH commonly selected it as the initial medication to be employed in the treatment of children with ADHD. Factors involved included its high efficacy, good safety record, and the ubiquitous nature of its appearance in the ADHD treatment literature.

CONCLUSIONS

MPH should be considered as the first medication to be used in a treatment algorithm for children and adolescents with ADHD.

Methylphenidate and substance abuse: a review of pharmacology, animal, and clinical studies

This article reviews pharmacological, animal, and human evidence regarding the abuse liability of methylphenidate (MPH). Findings are not always consistent, but evidence converges to suggest that although intravenous methylphenidate has some abuse potential, there is very little potential for oral MPH abuse. Furthermore, the available data suggests that children with Attention-Deficit/Hyperactivity Disorder (ADHD) who are treated with MPH are at lower risk for substance use disorder later in life. More longitudinal, prospective studies are needed to assess the long term effects of MPH treatment in ADHD.

Discriminant validity of the child behaviour checklist CBCL-4/18 in German samples

This study examined the discriminant validity of the German version of CBCL in two large samples of referred and non-referred children and adolescents which were matched for age, sex and socio-economic status. The combined sample that was used for statistical analysis consists of 2,058 referred and 2,058 non-referred boys and girls between 4 and 18 years of age (mean age: referred boys= 10.9 years, non-referred boys = 10.9 years, referred girls=11.3 years, non-referred girls=11.1 years). Referral status was used as validity criterion. Statistical procedures included Odds Ratios, Total Predictive Values, ROC analyses and discriminant analyses. Results indicated that the discriminant validity of the German version of CBCL is comparable to the original English version. With the use of CBCL Total Problem Score as predictor (cut-off T > or = 60) 83.8% of children and adolescents could correctly be classified (sensitivity 83.6%, specificity 83.9%). Symptoms of the "Attention Problems Scale" show the highest discriminative power to distinguish between disturbed and undisturbed children and adolescents.

[Cross-cultural comparison of Conners Scales: Can the US-American factorial structure be replicated on German clinical sample?]

OBJECTIVE

International networks in child psychiatry research increasingly rely on the cross-cultural generalizability of commonly used questionnaire factor structures. The aim of this study is to analyze whether the U.S. factor structure of the Conners Parent Rating Scale (CPRS) can be replicated in a German clinical sample.

METHOD

A German child psychiatry sample of 1394 children children and adolescents was randomly splitted into halves. One sub-sample was used to calculate a German factor model by means of exploratory factor analysis. This model is tested in comparison with he U.S. model constructed according to Conners (1989) in the second sub-sample by means of a confirmatory factor analysis (LISREL 8).

RESULTS

87% of the path relations in the German and U.S.-American models are identical. Both models show limitations with regard to their predictive power. As expected, the goodness of fit indices for the German model are somewhat better than for the U.S. model (GFI = .81; AGFI = .75 versus GFI = .76; AGFI = .71).

CONCLUSIONS

The goodness of fit indices of the CPRS model are less satisfactory than those of other studies on the cross-cultural generalizability of factor structures of dimensional questionnaires (i.e., De Groot et al., 1994). However, this is mainly due to restrictions within the model (no multiple factor loadings). With respect to the cross-cultural generalizability differences were found in the impulsiveness/hyperactivity scale. All other scales could be well replicated.

[Cross-cultural comparison of Conners Scales: Can the US-American factorial structure be replicated on German clinical sample?]

OBJECTIVE

International networks in child psychiatry research increasingly rely on the cross-cultural generalizability of commonly used questionnaire factor structures. The aim of this study is to analyze whether the U.S. factor structure of the Conners Parent Rating Scale (CPRS) can be replicated in a German clinical sample.

METHOD

A German child psychiatry sample of 1394 children children and adolescents was randomly splitted into halves. One sub-sample was used to calculate a German factor model by means of exploratory factor analysis. This model is tested in comparison with he U.S. model constructed according to Conners (1989) in the second sub-sample by means of a confirmatory factor analysis (LISREL 8).

RESULTS

87% of the path relations in the German and U.S.-American models are identical. Both models show limitations with regard to their predictive power. As expected, the goodness of fit indices for the German model are somewhat better than for the U.S. model (GFI = .81; AGFI = .75 versus GFI = .76; AGFI = .71).

CONCLUSIONS

The goodness of fit indices of the CPRS model are less satisfactory than those of other studies on the cross-cultural generalizability of factor structures of dimensional questionnaires (i.e., De Groot et al., 1994). However, this is mainly due to restrictions within the model (no multiple factor loadings). With respect to the cross-cultural generalizability differences were found in the impulsiveness/hyperactivity scale. All other scales could be well replicated.

[Day treatment in German child and adolescent psychiatry: analysis of data from a nationwide survey with respect to cost effectiveness]

Day treatment plays an increasingly important role in German child and adolescent psychiatry. In spite of a steady and ongoing increase of day treatment facilities over the past 15 years only few empicial data on the structure of German day treatment are available. The study refers to an Germany wide assessment of all day treatment centers (DTC). 45 out of 61 DTC responded (reply rate 74%). Analyses were done over 560 treatment places used by 69% male and 31% female patients mean ages 10 years and 2 months. Mean treatment duration is 104 days without differences with respect to the primary psychotherapeutic orientation (behavioral, psychodynamic, family therapy, other). Personnel is in 80.5% of the DTC below the governmental guidelines. Rates per day vary between 280 DM and 617 DM with a mean of 389 DM. Mean treatment costs per patient are 36.303 DM (min.: 12.825 DM; max.: 89.793 DM). Rates per day and duration of treatment are negatively correlated: The higher the rate per day, the shorter the treatment (explained variance: 17%). This correlation can only be explained indirectly by more personnel as associated with higher daily rates. However, more influential is the amount of time the children are present in day treatment per week: The longer the children are present, the shorter the duration of the whole treatment. Diagnosis, gender, and age only influence duration and costs of the treatment marginally. Network-effects as operationalized by the availability of additional inpatient and outpatient facilities did not influence costs and duration of day treatment.

A test for the diagnosis of dead regions in the cochlea

Hearing impairment may sometimes be associated with complete loss of inner hair cells (IHCs) over a certain region of the basilar membrane. We call this a 'dead region'. Amplification (using a hearing aid) over a frequency range corresponding to a dead region may not be beneficial and may even impair speech intelligibility. However, diagnosis of dead regions is not easily done from the audiogram. This paper reports the design and evaluation of a method for detecting and delimiting dead regions. A noise, called 'threshold equalizing noise' (TEN), was spectrally shaped so that, for normally hearing subjects, it would give equal masked thresholds for pure tone signals at all frequencies within the range 250-10,000 Hz. Its level is specified as the level in a one-ERB (132 Hz) wide band centred at 1000 Hz. Measurements obtained from 22 normal-hearing subjects and TEN levels of 30, 50 and 70 dB/ERB confirmed that the signal level at masked threshold was approximately equal to the noise level/ERB and was almost independent of signal frequency. Masked thresholds were measured for 20 ears of 14 subjects with sensorineural hearing loss, using TEN levels of 30, 50 and 70 dB/ERB. Psychophysical tuning curves (PTCs) were measured for the same subjects. When there are surviving IHCs corresponding to a frequency region with elevated absolute thresholds, a signal in that frequency region is detected via IHCs with characteristic frequencies (CFs) close to that region. In such a case, threshold in the TEN is close to that for normal-hearing listeners, provided that the noise intensity is sufficient to produce significant masking. Also, the tip of the PTC lies close to the signal frequency. When a dead region is present, the signal is detected via IHCs with CFs different from that of the signal frequency. In such a case, threshold in the TEN is markedly higher than normal, and the tip of the PTC is shifted away from the signal frequency. Generally, there was a very good correspondence between the results obtained using the TEN and the PTCs. We conclude that the measurement of masked thresholds in TEN provides a quick and simple method for the diagnosis of dead regions.

Three-dimensional structure and subunit topology of the V(1) ATPase from Manduca sexta midgut

The three-dimensional structure of the Manduca sexta midgut V(1) ATPase has been determined at 3.2 nm resolution from electron micrographs of negatively stained specimens. The V(1) complex has a barrel-like structure 11 nm in height and 13.5 nm in diameter. It is hexagonal in the top view, whereas in the side view, the six large subunits A and B are interdigitated for most of their length (9 nm). The topology and importance of the individual subunits of the V(1) complex have been explored by protease digestion, resistance to chaotropic agents, MALDI-TOF mass spectrometry, and CuCl(2)-induced disulfide formation. Treatment of V(1) with trypsin or chaotropic iodide resulted in a rapid cleavage or release of subunit D from the enzyme, indicating that this subunit is exposed in the complex. Trypsin cleavage of V(1) decreased the ATPase activity with a time course that was in line with the cleavage of subunits B, C, G, and F. When CuCl(2) was added to V(1) in the presence of CaADP, the cross-linked products A-E-F and B-H were generated. In experiments where CuCl(2) was added after preincubation of CaATP, the cross-linked products E-F and E-G were formed. These changes in cross-linking of subunit E to near-neighbor subunits support the hypothesis that these are nucleotide-dependent conformational changes of the E subunit.

Association of the neutral endopeptidase (MME) gene with anxiety

Enkephalins have been implicated in the regulation of mood, anxiety, reward, euphoria and pain. One of the major enzymes for enkephalin degradation is neutral endopeptidase [enkephalinase, membrane metalloendopeptidase (MME)]. We identified a dinucleotide polymorphism in the 5' region of the MME gene. Subjects were placed into three genotypes, 3/3, 3/x, and x/x since the 3 allele was the most common of the six alleles. Using one-way analysis of variance, we examined the association of these genotypes with the mean SCL-90 scores for anxiety, depression, obsessive-compulsive and phobic anxiety symptoms in 120 Caucasian males from an addiction treatment unit. There was a significant association between the MME genotypes and the SCL-90 scores for phobic anxiety, obsessive-compulsive and anxiety at a Bonferroni corrected alpha value of 0.0125. These results support a role of genetic variants of enkephalin metabolism in anxiety.

Association between the adrenergic alpha 2A receptor gene (ADRA2A) and measures of irritability, hostility, impulsivity and memory in normal subjects

The noradrenergic system has been implicated in arousal, vigilance, irritability hostility, and memory. This suggests the hypothesis that genetic variants at noradrenergic receptors may be risk factors of these behaviors. To test this hypothesis, the potential association between measures of these traits and genetic variation at the adrenergic2A receptor gene (ADRA2A), using a common single nucleotide polymorphism (SNP) polymorphism of the promoter region, were examined in two independent sets of subjects: university students (student group), and parents of twins in the Minnesota Twin Study (twin group). In the student group, there was a significant linear association by genotype (11 > 12 > 22) for the total Brown ADD score (BADD), and BADD subscores of memory and irritability, and with the total Buss-Durkee Hostility Inventory (BDHI) score and BDHI subscores of indirect hostility, irritability, negativity, and verbal aggression. A multiple analysis of variance (MANOVA) of all the BADD and BDHI subscores was significant at P < or = 0.009. For the twin group, the same genotype associations were significant for the Multidimensional Personality Questionnaire (MPQ) impulsivity scores but not for the MPQ aggression or harm avoidance scores. The ADRA2A gene accounted for 1.8-8.3% of the variance of these scores.

Structure and regulation of insect plasma membrane H(+)V-ATPase

H(+) V-ATPases (V-ATPases) are found in two principal locations, in endomembranes and in plasma membranes. The plasma membrane V-ATPase from the midgut of larval Manduca sexta is the sole energizer of all transepithelial secondary transport processes. At least two properties make the lepidopteran midgut a model tissue for studies of general aspects of V-ATPases. First, it is a rich source for purification of the enzyme and therefore for structural studies: 20 larvae provide up to 0.5 mg of holoenzyme, and soluble, cytosolic V(1) complexes can be obtained in even greater amounts of up to 2 mg. Second, midgut ion-tranport processes are strictly controlled by the regulation of the V-ATPase, which is the sole energizer of all ion transport in this epithelium. Recent advances in our understanding the structure of the V(1) and V(o) complexes and of the regulation of the enzyme's biosynthesis and ion-transport activity will be discussed.

A novel insect V-ATPase subunit M9.7 is glycosylated extensively

Plasma membrane V-ATPase isolated from midgut and Malpighian tubules of the tobacco hornworm, Manduca sexta, contains a novel prominent 20-kDa polypeptide. Based on N-terminal protein sequencing, we cloned a corresponding cDNA. The deduced hydrophobic protein consisted of 88 amino acids with a molecular mass of only 9.7 kDa. Immunoblots of the recombinant 9.7-kDa polypeptide, using a monoclonal anti- body to the 20-kDa polypeptide, confirmed that the correct cDNA had been cloned. The 20-kDa polypeptide is glycosylated, as deduced from lectin staining. Treatment with N-glycosidase A resulted in the appearance of two additional protein bands of 16 and 10 kDa which both were immunoreactive to the 20-kDa polypeptide-specific monoclonal antibody. Thus, extensive N-glycosylation of the novel Vo subunit M9.7 accounts for half of its molecular mass observed in SDS-polyacrylamide gel electrophoresis. M9.7 exhibits some similarities to the yeast protein Vma21p which resides in the endoplasmic reticulum and is required for the assembly of the Vo complex. However, as deduced from immunoblots as well as from activities of the V-ATPase and endoplasmic reticulum marker enzymes in different membrane preparations, M9.7 is, in contrast to the yeast polypeptide, a constitutive subunit of the mature plasma membrane V-ATPase of M. sexta.

The plasma membrane H+-V-ATPase from tobacco hornworm midgut

The midgut plasma membrane V-ATPase from larval Manduca sexta, the tobacco hornworm, is the sole energizer of any epithelial ion transport in this tissue and is responsible for the alkalinization of the gut lumen up to a pH of more than 11. This mini-review deals with those topics of research on this enzyme which may have contributed or are expected to contribute novel and general aspects to the field of V-ATPases. Topics dealt with include novel subunits or the quaternary structure of the V1 complex, as well as the regulation of the enzyme's function by reversible dissociation of the V1 from the V0 complexes and by genetic control on the transcriptional and posttranscriptional level.

Quaternary structure of V1 and F1 ATPase: significance of structural homologies and diversities

The V1 ATPase from the tobacco hornworm Manduca sexta and the Escherichia coli F1 ATPase were characterized by small-angle X-ray scattering (SAXS). The radii of gyration (Rg) of the complexes were 6.2 +/- 0.1 and 4.7 +/- 0.02 nm, respectively. The shape of the M. sexta V1 ATPase was determined ab initio from the scattering data showing six masses, presumed to be the A and B subunits, arranged in an alternating manner about a 3-fold axis. A seventh mass with a length of about 11.0 nm extends perpendicularly to the center of the hexameric unit. This central mass is presumed to be the stalk that connects V1 with the membrane domain (V(O)) in the intact V1V(O)-ATPase. In comparison, the shape of the F1 ATPase from E. coli possesses a quasi-3-fold symmetry over the major part of the enzyme. The overall asymmetry of the structure is given by a stem, assumed to include the central stalk subunits. The features of the V1 and F1 ATPase reveal structural homologies and diversities of the key components of the complexes.

[Incidence of psychiatric symptoms and somatic complaints in 4- to 10-year-old children in Germany as judged by parents--a comparison of norm-oriented and criteria-oriented models]

OBJECTIVES

To analyze the frequency of behavioral/emotional problems and somatic complaints of children aged four to ten as rated by their parents.

METHOD

The analysis is based on the PAK-KID study on behavioural and emotional problems and psychosocial competencies of children and adolescents in Germany. In a nationally representative sample of N = 1030 children aged four to ten years the parents rated their child using the Child Behavior Checklist.

RESULTS

The prevalence rates of the symptoms are presented. Additionally global prevalence rates based on three different models were calculated and compared. They range from 13.1% to 28.3%. The issues of defining cutoffs necessary for the calculation of prevalence rates are discussed.

[Mental disturbances in children and adolescents in Germany. Results of a representative study:age,gender and rater effects]

METHOD

A study on behavioral and emotional problems and competence in children and adolescents in Germany (PAK-KID study) is described. It is the first nationwide representative survey of this kind of children and adolescents aged 4 to 18 years in Germany. For children aged 4 to 10 years the parents completed the German version of Achenbach's Child Behavior Checklist (CBCL 4-18) developed by the Arbeitsgruppe Deutsche Child Behavior Checklist. Children and adolescents aged 11 years and older filled out the German version of the Youth Self-Report that is part of Achenbach's CBCL in addition to the parents completing the German version of the CBCL. A total of 2856 parent questionnaires and 1798 self-report questionnaires completed by children and adolescents were analyzed.

RESULTS

The sample was representative with respect to the main sociodemographic variables. On all problem scales children and adolescents aged 11 to 18 years reported significantly more problems than their parents did. The frequency of internalizing problems (social withdrawal, somatic complaints, anxiety/depression) and delinquent behavior of children and adolescents reported by parents increased with the children's age, whereas aggressive behavior and attention problems decreased with age. Girls reported significantly more problems than boys on all internalizing scales of the Youth Self-Report. The effect was not totally replicated in the parent reports. In the parent reports, boys had more attention problems and more aggressive and delinquent behavior than girls.

Children's ability to delay gratification: longitudinal relations to mother-child attachment

Concurrent and longitudinal mother-child attachment qualities were studied in relation to children's ability to postpone gratification at age 6 years. A sample of 32 children (at ages 12 months and 18 months) and their mothers participated in the strange situation procedure. At age 6 years, they were observed in an attachment situation and administered a standard delay of gratification task. The length of time that children were able to delay gratification at age 6 was predicted both by concurrent attachment quality and by a longitudinal attachment measure. Children with secure attachment were able to wait the longest periods of time, whereas those with insecure-disorganized attachment had the most difficulties in waiting. The effects of longitudinal, but not concurrent, attachment quality on children's total waiting time remained significant when other important variables were considered, including gender and children's cognitive functioning. An interactive effect was found between attachment quality and cognitive functioning. Insecure-avoidantly attached children with high cognitive functioning did not differ in their overall waiting times from securely attached children, but insecure-avoidantly attached children with average or low cognitive functioning did have shorter waiting times. The study provides a basis for the further investigation of mother-child attachment quality as a factor that is linked to children's delay behavior.

[The value of different sources of information in evaluating psychiatric disorders in adolescence--a comparison of parental judgment and self-assessment by adolescents]

Data from the national representative epidemiologic survey (PAK-KID-study) assessed by the German versions of Achenbach'S Child Behavior Checklist and Youth Self-Report of N = 1757 parents and their children aged 11 to 18 years are compared by using the corresponding Cross-Informant-Scales. On all problem scales adolescents report more problems than parents. For some scales the differences between girls and their parents are higher than between boys and their parents (social withdrawal, somatic complaints, anxious/depressed, attention problems, internalizing and total score). Averaged Pearson correlations of the eight subscales are in a moderate rage (r < 0.50). For all problem scales an agreement of 30% in the area of high problems (> PR95) is found. If one informant scores above PR95 the Relative Risk of the other one scoring in this range too is significantly higher than one for nearly all scales.

Regulation of proton-translocating V-ATPases

Vacuolar-type ATPases (V-ATPases) are proton-translocating enzymes that occur in the endomembranes of all eukaryotes and in the plasma membranes of many eukaryotes. They are multisubunit, heteromeric proteins composed of two structural domains, a peripheral, catalytic V1 domain and a membrane-spanning V0 domain. Both the multitude of locations and the heteromultimeric structure make it likely that the expression and the activity of V-ATPases are regulated in various ways. Regulation of gene expression encompasses control of transcription as well as control at the post-transcriptional level. Regulation of enzyme activity encompasses many diverse mechanisms such as disassembly/reassembly of V1 and V0 domains, oxidation of SH groups, control by activator and inhibitor proteins or by small signalling molecules, and sorting of the holoenzyme or its subunits to target membranes.