Biomedical subjects

H van Engeland

Publications and source records attributed to H van Engeland.

At least 19 recordsLinked to original sources

PubMed2007

Visual information processing in high-functioning individuals with autism spectrum disorders and their parents.

The authors assessed visual information processing in high-functioning individuals with pervasive developmental disorders (PDD) and their parents. The authors used tasks for contrast sensitivity, motion, and form perception to test visual processing occurring relatively early and late in the magnocellular-dorsal and parvocellular-ventral pathways. No deficits were found in contrast sensitivity for low or high spatial frequencies or for motion or form perception between individuals with PDD in comparison with a matched control group. Individuals with PDD performed equally with or better than controls on motion detection tasks. In addition, the authors did not find differences on any of the tasks between parents of the PDD group and matched control parents. These results indicate that high-functioning individuals with PDD and their parents are able to process visual stimuli that rely on early or late processing in the magnocellular-dorsal and parvocellular-ventral pathways as well as controls.

Adolescent↗

PubMed2006

Integrity of lateral and feedbackward connections in visual processing in children with pervasive developmental disorder.

Enhanced visual detail processing in subjects with pervasive developmental disorder (PDD) has been related to impairments in feature integration. The functional integrity of two types of neuronal connections involved in visual feature integration, namely horizontal and feedbackward connections, were tested. Sixteen children with PDD and 17 age- and IQ-matched control children (mean age 13.3 years) were included. In a texture segregation task the difference in ERP response to homogeneous and checkered visual stimuli was determined. Additionally, in a contour integration task subjects had to point out a contour consisting of colinearly aligned Gabor signals in backgrounds increasing in noise. Children with PDD showed a normal performance on the contour integration task, suggesting that neurons in the primary visual cortex of children with PDD can effectively integrate the activity of local detectors that process different aspects of the same object information by making use of long-range lateral connections. The amplitude of ERP activity related to texture segregation was also not different between the PDD and control groups, indicating functional visual feedback mechanisms between V1 and higher order areas in subjects with PDD. However, a difference in latency of texture-segmentation related activity between the groups was noted. This effect did not reach significance, which could be due to the small N of the study. Therefore, the data need replication in a study with larger samples before more definitive conclusions can be drawn.

Adolescent↗

PubMed2006

Proton magnetic resonance spectroscopy in developmentally delayed young boys with or without autism.

OBJECTIVE: The aim of the present study is to investigate whether brain metabolism of boys with autism spectrum disorder (ASD) is altered compared to boys with a developmental delay without autism if corrected for patient age and developmental level. STUDY DESIGN: 25 boys with ASD (with or without concurrent mental retardation) and 12 boys without ASD with mental retardation or language disorder underwent proton magnetic resonance spectroscopy. All analyses were performed with chronological age and developmental level as independent variables. RESULTS: No metabolic differences were found between boys with ASD and without ASD. CONCLUSIONS: Our findings do not replicate previous reports of differences in NAA, Cho and Cr levels in ASD.

Age Factors↗

PubMed2006

Adolescent outcome of disruptive behaviour disorder in children who had been treated in in-patient and day-treatment settings.

Although several studies have been conducted on the longitudinal course of childhood disruptive behaviours in community samples and in general psychiatric samples, little is known about adolescent adjustment in psychiatrically treated disruptive behaviour disorder (DBD) children. We examined a sample of adolescents (n = 47) who had been treated as children in an in-patient and/or day-treatment setting because of their severely disruptive behaviour. At follow-up, we found that half of the adolescents had a DBD diagnosis, and on average higher numbers of participants ever used soft drugs, had ever been in court, were not attending school when this was mandatory, and were smoking on a daily basis, as compared to comparison groups. There was, however, a large variance among the adolescents of our sample. When outcome was defined in terms of DBD diagnosis, living status, delinquency, school attendance, and smoking behaviour, 38 % had a positive outcome and 34 % had a poor outcome. For clinical purposes, it is important to recognise that there are large individual differences in outcome.

Adolescent↗

PubMed2006

Identification of novel autism candidate regions through analysis of reported cytogenetic abnormalities associated with autism.

The identification of the candidate genes for autism through linkage and association studies has proven to be a difficult enterprise. An alternative approach is the analysis of cytogenetic abnormalities associated with autism. We present a review of all studies to date that relate patients with cytogenetic abnormalities to the autism phenotype. A literature survey of the Medline and Pubmed databases was performed, using multiple keyword searches. Additional searches through cited references and abstracts from the major genetic conferences from 2000 onwards completed the search. The quality of the phenotype (i.e. of the autism spectrum diagnosis) was rated for each included case. Available specific probe and marker information was used to define optimally the boundaries of the cytogenetic abnormalities. In case of recurrent deletions or duplications on chromosome 15 and 22, the positions of the low copy repeats that are thought to mediate these rearrangements were used to define the most likely boundaries of the implicated 'Cytogenetic Regions Of Interest' (CROIs). If no molecular data were available, the sequence position of the relevant chromosome bands was used to obtain the approximate molecular boundaries of the CROI. The findings of the current review indicate: (1) several regions of overlap between CROIs and known loci of significant linkage and/or association findings, and (2) additional regions of overlap among multiple CROIs at the same locus. Whereas the first finding confirms previous linkage/association findings, the latter may represent novel, not previously identified regions containing genes that contribute to autism. This analysis not only has confirmed the presence of several known autism risk regions but has also revealed additional previously unidentified loci, including 2q37, 5p15, 11q25, 16q22.3, 17p11.2, 18q21.1, 18q23, 22q11.2, 22q13.3 and Xp22.2-p22.3.

Autistic Disorder↗

PubMed2006

Electrocortical reflections of face and gaze processing in children with pervasive developmental disorder.

BACKGROUND: Children with pervasive developmental disorder (PDD) show behavioral abnormalities in gaze and face processing, but recent studies have indicated that normal activation of face-specific brain areas in response to faces is possible in this group. It is not clear whether the brain activity related to gaze processing is also normal in children with PDD. METHODS: Event-related brain potentials (ERPs) were measured during two spatial attention tasks in which a centrally presented stimulus served as cue for the location of a forthcoming target. In one task faces were used as cues, and in the other arrows. Seventeen children with PDD and 18 age- and IQ-matched control children were tested. RESULTS: Face stimuli elicited the same specific ERP activity in both groups. Also, both children with PDD and controls showed shorter reaction times as well as larger amplitudes and shorter latency times of several ERP peaks to congruently cued targets than to incongruently cued targets in both tasks. However, children with PDD showed abnormally small occipital ERPs in response to both face and arrow stimuli. CONCLUSIONS: The results provide evidence for the capability of normal processing of face and gaze change in children with PDD. The smaller occipital activity might be related to more general abnormalities in perception.

Adolescent↗

PubMed2005

The relationship between local and global processing and the processing of high and low spatial frequencies studied by event-related potentials and source modeling.

The processing of global and local elements and of low- and high-spatial frequencies are thought to be interrelated. Evidence for this stems from findings showing that brain localizations for global/local elements and for low/high spatial frequencies seem to overlap. The present study aimed to provide direct evidence that topographical differences between the processing of global and local visual elements can directly be explained by their spatial frequency content, and to study at which point in time this relation is present. This was done by studying the event-related potentials (ERPs) and source models elicited by unfiltered, low- or high-pass filtered hierarchical stimuli. Results showed that performance for global and local targets was affected by removing low and high spatial frequencies, respectively. ERP data indicated that at 250 ms, there was an interaction between the processing of global/local targets and of spatial frequencies because at this time-point removal of low spatial frequencies decreased activity associated with the processing of global targets. When localizing this effect, we found evidence implying that spatial frequency content indeed affected the brain region in which local/global targets were processed. Results implicated that the processing of global information depended on its low spatial frequency content, which was processed more laterally. Instead, processing of local information seemed to depend on its high spatial frequency content, which was processed more medially. Thereby, present results extend former results showing that global and local processing is dependent on spatial frequency and mapped retinotopically in the visual cortex.

Adolescent↗

PubMed2005

Time-varying differences in evoked potentials elicited by high versus low spatial frequencies: a topographical and source analysis.

OBJECTIVE: To investigate time-varying differences in visual-evoked potentials (VEPs) and dipoles elicited by high versus low spatial frequencies. The main question was whether different spatial frequencies are processed in distinct cortical areas, especially after 100 ms. An additional question was whether and how a hemispheric balance in spatial frequency processing develops over time. METHODS: Stimuli were square-wave gratings, with spatial frequencies of 0.75, 1.5, and 6 c/d. VEPs and dipole models were analyzed at various latencies. RESULTS: For the time-window of 80-100 ms, spatial frequency-related differences in VEPs and dipoles in posterior regions as reported previously were replicated: lower spatial frequencies were associated with more positivity in the VEP and with more anterior and radial sources than high frequencies. However, after 100 ms differences in amplitude, but not in topography and dipoles, were found between the different spatial frequencies. Between 180-200 ms a right hemisphere dominance was found for all frequencies. CONCLUSIONS: After 100 ms, VEPs in response to different spatial frequencies seem to be generated in the same cortical areas. Also, no evidence for frequency-related hemispheric lateralization was found. SIGNIFICANCE: Insight is provided into the functional-anatomical basis of longer-latency frequency-related differences in processing.

Adolescent↗

PubMed2005

Differential effects of DRD4 and DAT1 genotype on fronto-striatal gray matter volumes in a sample of subjects with attention deficit hyperactivity disorder, their unaffected siblings, and controls.

Genetic influences on behavior are complex and, as such, the effect of any single gene is likely to be modest. Neuroimaging measures may serve as a biological intermediate phenotype to investigate the effect of genes on human behavior. In particular, it is possible to constrain investigations by prior knowledge of gene characteristics and by including samples of subjects where the distribution of phenotypic variance is both wide and under heritable influences. Here, we use this approach to show a dissociation between the effects of two dopamine genes that are differentially expressed in the brain. We show that the DAT1 gene, a gene expressed predominantly in the basal ganglia, preferentially influences caudate volume, whereas the DRD4 gene, a gene expressed predominantly in the prefrontal cortex, preferentially influences prefrontal gray matter volume in a sample of subjects including subjects with ADHD, their unaffected siblings, and healthy controls. This demonstrates that, by constraining our investigations by prior knowledge of gene expression, including samples in which the distribution of phenotypic variance is wide and under heritable influences, and by using intermediate phenotypes, such as neuroimaging, we may begin to map out the pathways by which genes influence behavior.

Adolescent↗

PubMed2004

Salivary cortisol and aggression in a population-based longitudinal study of adolescent males.

Chronic antisocial behaviour in youth has been associated with cortisol, a measure of stress reactivity. However, some studies have found low cortisol levels, while others have found elevated cortisol levels. The present study compared variously defined aggressive subgroups for differences in salivary cortisol. A population-based sample of boys was followed longitudinally from childhood to adolescence. Assessments of different forms of antisocial behaviour were obtained from various informants at several points in time, and cortisol was collected at age 13. Higher cortisol levels were found in boys with conduct disorder (CD) than in boys without CD. In addition, boys with an aggressive form of CD had higher cortisol levels than boys who showed a covert form of CD. Furthermore, reactive aggression was strongly correlated with elevated cortisol. Adolescent boys with chronic reactive aggression and those who scored high on aggressive CD symptoms seem to have a more active hypothalamic-pituitary-adrenal system.

Adolescent↗

PubMed2004

In search of neurophysiological markers of pervasive developmental disorders: smooth pursuit eye movements?

Genetic studies of autism would benefit from the identification of (neurophysiological) markers of the disease. Reports that subjects with autism suffer from abnormalities of visual motor processing, indicate that abnormalities in smooth pursuit eye movements (SPEM) may be a marker of the disorder. Sixteen high-functioning school-aged children with pervasive developmental disorder (PDD) were compared with a matched group of eighteen normally developing controls on performance of a SPEM task and a task which tested the integrity of visually guided saccadic eye movements. Both groups of children had normal eye movements during performance of these tasks. Thus abnormalities in SPEM would appear not to be a marker of PDD. The earlier reported abnormalities in visual motion processing might need to be reinterpreted.

Child↗

PubMed2004

Review on structural neuroimaging findings in autism.

Autism is now widely viewed as a neurodevelopmental disorder, although the underlying biological causes remain to be established. In this review, we examine the literature in magnetic resonance imaging (MRI) as applied to autism, discuss the findings that have emerged, and give directions for potential future research. To date, structural MRI results are inconsistent, partly due to the heterogeneity of the disorder itself, and partly due to the different composition and the varied degree of matching of the studied groups. However, recent studies have begun to elucidate the underlying neuroanatomical abnormalities and brain-behavior relationships in autism, with the most consistent finding being increased brain volume in autism. Future large-scale longitudinal structural imaging studies, starting at very young ages, investigating homogeneous groups of patients and extensively matched control groups, and making use of (combinations of) newer and more sophisticated techniques, hold a great promise to further elucidate the enigma of autism.

Age Factors↗

PubMed2004

Dipole source localization of event-related brain activity indicative of an early visual selective attention deficit in ADHD children.

OBJECTIVE: This study was aimed at investigating whether attention-deficit hyperactivity disorder (ADHD) children suffer from specific early selective attention deficits in the visual modality with the aid of event-related brain potentials (ERPs). Furthermore, brain source localization was applied to identify brain areas underlying possible deficits in selective visual processing in ADHD children. METHODS: A two-channel visual color selection task was administered to 18 ADHD and 18 control subjects in the age range of 7-13 years and ERP activity was derived from 30 electrodes. RESULTS: ADHD children exhibited lower perceptual sensitivity scores resulting in poorer target selection. The ERP data suggested an early selective-attention deficit as manifested in smaller frontal positive activity (frontal selection positivity; FSP) in ADHD children around 200 ms whereas later occipital and fronto-central negative activity (OSN and N2b; 200-400 ms latency) appeared to be unaffected. Source localization explained the FSP by posterior-medial equivalent dipoles in control subjects, which may reflect the contribution of numerous surrounding areas. CONCLUSIONS: ADHD children have problems with selective visual processing that might be caused by a specific early filtering deficit (absent FSP) occurring around 200 ms. The neural sources underlying these problems have to be further identified. Source localization also suggested abnormalities in the 200-400 ms time range, pertaining to the distribution of attention-modulated activity in lateral frontal areas.

Attention↗

PubMed2003

Effects of methylphenidate, desipramine, and L-dopa on attention and inhibition in children with Attention Deficit Hyperactivity Disorder.

The objective of this study was to investigate the effects of methylphenidate (MPH) on attention and inhibition in children with Attention Deficit Hyperactivity Disorder (ADHD) and to establish what the relative contributions of the noradrenergic and dopaminergic systems to this effect were. In addition to MPH, two other drugs were administered in order to affect both transmitter systems more selectively, L-dopa (dopamine (DA) agonist) and desipramine (DMI) (noradrenaline (NA) re-uptake inhibitor). Sixteen children with ADHD performed a stop-task, a laboratory task that measures the ability to inhibit an ongoing action, in a double-blind randomized within-subjects design. Each child received an acute clinical dose of MPH, DMI, L-dopa, and placebo; measures of performance and plasma were determined. The results indicated that inhibition performance was improved under DMI but not under MPH or L-dopa. The response-time to the stop-signal was marginally shortened after intake of DMI. MPH decreased omission and choice-errors and caused faster reaction times to the trials without the stop-tone. No effects of L-dopa whatsoever were noted. Prolactin levels were increased and 5-HIAA levels were lowered under DMI relative to placebo. It is suggested that the effects of MPH on attention are due to a combination of noradrenergic and dopaminergic mechanisms. The improved inhibition under DMI could be serotonergically mediated.

Attention↗

PubMed2003

Do integrated mental healthcare organisations facilitate process quality in the treatment of people with schizophrenia and related psychoses?

OBJECTIVE: The objective of this study is to investigate the influence of mergers of ambulatory and mental healthcare organisations on the process quality of care for persons suffering from schizophrenia or related psychoses. THEORY: On the basis of the theory of Donabedian we assume the relationships between three types of quality in healthcare: structure quality, process quality and outcome quality. This study focuses on the influences of structure quality, i.e. years since merger and catchment area size upon process quality. METHODS: Criteria according to Tugwell for evaluating healthcare were used to describe the process quality of schizophrenia care, resulting in a process quality questionnaire with 6 subscales and 21 items. Leading psychiatrists of 31 Dutch mental healthcare organisations, covering 89% of the country, answered the questionnaire. Both programmes and documents from the responding institutions and schizophrenia projects were analysed. Correlations of two determinants, age of the merged organisation and catchment area size, were made with total scale scores and the sub scores of the questionnaire. RESULTS: The response rate was 97% (31/32). Twenty-two organisations (71%) had a score of more than 50% on the used scale, 8 (29%) scored less. Two evidence-based interventions were implemented in more than 50% of the organisations, three in less than 50%. A low degree of implementation occurs in establishing care for people with schizophrenia from ethnic minorities, standardising diagnostic procedures and continuity of care. No significant relationship between the age of the merged organisation ('age') and the total process quality of schizophrenia care was found, however, the relationships between age and the subscales availability of interventions and integrated treatment were significant. No association was found between the size of the MHO's catchment area and any of the used subscales. CONCLUSIONS: The age of integration of residential and ambulatory mental health institutions correlates significantly with two subscales of process quality of schizophrenia care, i.e. availability of interventions and treatment. Catchment area size is not significantly associated with process quality or any of the subscales. Despite the mentioned positive effects, the overall picture of schizophrenia care is not very positive. Additional forces other than merely integration of ambulatory and residential services are needed for the further implementation of evidence-based interventions, diagnostic standards and continuity of care. The development of a national 'schizophrenia standard' (like in other countries) in relation with implementation plans and strategies to evaluate care on a regional level is recommended as well as further research on patient outcomes in relation to mergers of mental healthcare organisations.

Journal Article↗

PubMed2002

Do adolescent anorexia nervosa patients have deficits in emotional functioning?

Adult eating disorder patients have been characterised by alexithymia. We investigated whether adolescent eating disorder patients also show deficits in emotional functioning. To measure emotional functioning a questionnaire (the TAS) and an emotion recognition test were administered to 30 eating disorder (ED) adolescent girls and 31 healthy controls (HC), matched for age, education, and social status. Non-emotional, cognitive parallel tasks were administered on the same occasion to find out whether a possible deficit was emotion-specific or of a more general cognitive nature. The ED patients scored higher on the TAS and performed worse on the emotion recognition test, but no differences between the groups were found on the non-emotional cognitive instruments. It was concluded that adolescent eating disorder patients, just like adult eating disorder patients, are characterised by alexithymia and show specific deficits in emotional functioning. The implications of these findings are discussed.

Adolescent↗

PubMed2002

Effective treatments of school-aged conduct disordered children: recommendations for changing clinical and research practices.

The present article discusses reviews, meta-analytical and other relevant outcome studies of treating school-aged conduct-disordered children. Meta-analytical studies of Parent Management Training and Cognitive-behavioural Therapy for the child have demonstrated that these interventions affect conduct disorder in children positively. However, most studies involved in these meta-analyses are conducted in research conditions and are not representative of the treatment effectiveness in everyday clinical practice. We believe there is a gap between the so-called efficacy studies in research conditions and the effectiveness studies in clinical practice and we discuss how clinical and research practice could be brought together.

Adolescent↗

PubMed2002

Looking at images with human figures: comparison between autistic and normal children.

Based on clinical observations of abnormal gaze behavior of autistic children, it has been suggested that autistic children have a problem in processing social information. Several studies on eye movements have indeed found indications that children with autism show particularly abnormal gaze behavior in relation to social stimuli. However, the methodology used in such investigations did not allow for precise gaze analysis. In the present study, the looking behavior of autistic children toward cartoon-like scenes that included a human figure was measured quantitatively using an infrared eye-tracking device. Fixation behavior of autistic children was similar to that of their age- and IQ-matched normal peers. These results do not support the notion that autistic children have a specific problem in processing socially loaded visual stimuli. Also, there is no indication for an abnormality in gaze behavior in relation to neutral objects. It is suggested that the often-reported abnormal use of gaze in everyday life is not related to the nature of the visual stimuli but that other factors, like social interaction, may play a decisive role.

Autistic Disorder↗