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Eric Taylor

Publications and source records attributed to Eric Taylor.

At least 37 records · Page 2Linked to original sources
PubMed2005

Unravelling the complexity of attention-deficit hyperactivity disorder: a behavioural genomic approach.

International research has established that there is a strong genetically inherited contribution to attention-deficit hyperactivity disorder (ADHD) and the genetic mechanisms involved are being sought with considerable success. It is now established that certain alleles of the genes coding for the dopamine D4 receptor and the dopamine transporter occur more frequently in children with ADHD than in healthy controls, and we are finding other DNA changes associated with ADHD. A major challenge for the field now is to clarify how genetic susceptibility is translated into disorder by integrating the fields of quantitative and molecular genetics, neuropsychology and environmental risks.

Attention Deficit Disorder with Hyperactivity↗
PubMed2004

Polymorphisms in the dopamine D5 receptor (DRD5) gene and ADHD.

There is considerable evidence to support a role of dopamine-related genes in the molecular aetiology of attention-deficit hyperactivity disorder (ADHD). A microsatellite located near the dopamine D5 receptor (DRD5) gene has been associated with ADHD in a number of studies, but other polymorphisms within the vicinity of this gene have not been examined. In this study we genotyped three microsatellites spanning the DRD5 region in a large clinical sample. Overall, we found little evidence to support a role for DRD5 in ADHD. We found no evidence of association with either the previously associated DRD5 marker, or a repeat in the promoter region of the gene. We did, however, find significant association for an allele of D4S615, a dinucleotide repeat located 131 kb 3' of DRD5 that has been previously associated with schizophrenia. A global test incorporating all alleles of this marker, however, was not significant and thus this finding needs replication before any conclusions can be made.

Attention Deficit Disorder with Hyperactivity↗
PubMed2004

Neural correlates of switching set as measured in fast, event-related functional magnetic resonance imaging.

Attentional switching has shown to involve several prefrontal and parietal brain regions. Most cognitive paradigms used to measure cognitive switching such as the Wisconsin Card Sorting Task (WCST) involve additional cognitive processes besides switching, in particular working memory (WM). It is, therefore, questionable whether prefrontal brain regions activated in these conditions, especially dorsolateral prefrontal cortex (DLPFC), are involved in cognitive switching per se, or are related to WM components involved in switching tasks. Functional magnetic resonance imaging (fMRI) was used to examine neural correlates of pure switching using a paradigm purposely designed to minimize WM functions. The switching paradigm required subjects to switch unpredictably between two spatial dimensions, clearly indicated throughout the task before each trial. Fast, event-related fMRI was used to compare neural activation associated with switch trials to that related to repeat trials in 20 healthy, right-handed, adult males. A large cluster of activation was observed in the right hemisphere, extending from inferior prefrontal and pre- and postcentral gyri to superior temporal and inferior parietal cortices. A smaller and more caudal cluster of homologous activation in the left hemisphere was accompanied by activation of left dorsolateral prefrontal cortex (DLPFC). We conclude that left DLPFC activation is involved directly in cognitive switching, in conjunction with parietal and temporal brain regions. Pre- and postcentral gyrus activation may be related to motor components of switching set.

Adult↗
PubMed2004

PTSD and depression in refugee children: associations with pre-migration trauma and post-migration stress.

This paper describes the effect of pre-migration and post-migration experiences on the mental health of a sample of 40 refugee children aged 8-16 who lived in London with at least one parent or a refugee relative. Children's post-traumatic stress disorder (PTSD) and depression symptoms were assessed with standardised self-report measures (Impact of Event Scale and Depression Self-Rating Scale for Children, respectively). Information regarding past and present experiences were gathered during an interview with parents. There was a significant correlation between the number of pre-migration traumas experienced by the families and the children's PTSD scores. There was also a significant correlation between the families' number of post-migration stresses and children's depression scores. Higher PTSD scores were significantly associated with the pre-migration experience of violent death of family members and the post-migration experience of an insecure asylum status. Higher depression scores were significantly associated with insecure asylum status and severe financial difficulties. The clinical implications of these findings are discussed.

Adolescent↗
PubMed2004

European clinical guidelines for hyperkinetic disorder -- first upgrade.

BACKGROUND: The validity of clinical guidelines changes over time, because new evidence-based knowledge and experience develop. OBJECTIVE: Hence, the European clinical guidelines on hyperkinetic disorder from 1998 had to be evaluated and modified. METHOD: Discussions at the European Network for Hyperkinetic Disorders (EUNETHYDIS) and iterative critique of each clinical analysis. Guided by evidence-based information and based on evaluation (rather than metaanalysis) of the scientific evidence a group of child psychiatrists and psychologists from several European countries updated the guidelines of 1998. When reliable information is lacking the group gives a clinical consensus when it could be found among themselves. RESULTS: The group presents here a set of recommendations for the conceptualization and management of hyperkinetic disorder and attention deficit/hyperactivity disorder (ADHD). CONCLUSION: A general scheme for practice in Europe could be provided, on behalf of the European Society for Child and Adolescent Psychiatry (ESCAP).

Alleles↗
PubMed2004

International consensus statement on attention-deficit/hyperactivity disorder (ADHD) and disruptive behaviour disorders (DBDs): clinical implications and treatment practice suggestions.

Researchers and clinicians worldwide share concerns that many youngsters with attention-deficit/hyperactivity disorder (ADHD) and/or disruptive behaviour disorders (DBDs) do not receive appropriate treatment despite availability of effective therapies. At the request of Johnson and Johnson (sponsor), 11 international experts in child and adolescent psychiatry were selected by Professor Stan Kutcher (chair) to address these concerns. This paper describes the experts' consensus conclusions, including treatment practice suggestions for physicians involved in the early treatment of youngsters with ADHD (or hyperkinetic disorder, in countries preferring this classification) and/or DBDs internationally: suggested first-line treatment for ADHD without comorbidity is psychostimulant medication aided by psychosocial intervention. For ADHD with comorbid conduct disorder (CD), psychosocial intervention combined with pharmacotherapy is suggested. For primary CD, suggested first-line treatment is psychosocial intervention, with pharmacotherapy considered as an 'add-on' when aggression/impulsivity is marked and persistent. Pharmacotherapy requires careful titration; full-day coverage is the suggested goal. Regular long-term follow-up is recommended.

Attention Deficit Disorder with Hyperactivity↗
PubMed2004

Dopamine appetite and cognitive impairment in attention deficit/hyperactivity disorder.

The underlying defects in ADHD (Attention Deficit/Hyperactivity Disorder) are not yet clear. The current paper tests three existing theories: State Regulation, Cognitive Deficit, and Temporal Difference (TD) learning. We present computational simulations of the Matching Familiar Figures Task and compare these with the experimental results reported by Sonuga-Barke (2002). The TD model contains four parameters: the learning rate, discounting for future rewards, brittleness (randomness) of behavior, and action bias. The results show that the basic TD model accounts well for control performance in trials of 5 sec, 10 sec, and 15 sec duration; but not for the deficits in ADHD performance at 5 sec and 15 sec. Extending the TD model to incorporate either a state regulation deficit, or working memory deficit and delay in starting trials, can provide a good account of both control and ADHD results, at all trial-lengths. We discuss the significance of the results for theories of ADHD and make suggestions for future experimentation.

Algorithms↗
PubMed2004

Detection of child mental health disorders by general practitioners.

BACKGROUND: Few children with mental disorders access specialist services. Although previous studies suggest that general practitioner (GP) recognition is limited, parents may not be presenting these problems. AIM: To compare GP recognition of disorders with child mental health data and to examine factors affecting recognition, in particular whether recognition is enhanced if the parent expresses concern during the consultation. DESIGN OF STUDY: A two-phase design involving an initial community survey of children between the ages of 5 and 11 years. In the second phase, primary care attenders who were regarded by their GP as having a mental health disorder were compared with those who were not. SETTING: Five general practices in Croydon, outer London. METHOD: For 186 children attending primary care, GP recognition of disorders was compared with the results of a child mental health questionnaire completed by parents. Accuracy and predictors of GP recognition were examined. RESULTS: Seventy-four per cent of children meeting criteria for caseness were not recognised by GPs as having a mental health disorder. The expression of parental concern in the consultation about a mental health problem increased the sensitivity of recognition from 26% to 88%. Expression of concern also increased GP recognition of non-cases; this reflected GP identification of other mental health and learning problems. Only a third of parents who had concerns expressed these during the consultation. CONCLUSIONS: GPs are responsive to concern and take parental views into account. As well as detecting disorders, GPs are also sensitive to other psychosocial and educational problems that may present in primary care. There is a need for parental education about child mental health disorders.

Child↗
PubMed2004

Overview of SHOT hardware capabilities and range of cell biology experiment designs.

Cell science hardware is currently available for lease or production by SHOT(R). The SHOT Avian Development Facility (ADF) is a single middeck locker experiment containing two carousels capable of rotating at variable g. Each carousel accommodates 18 40-ml vessels that can be adapted for the cultivation of avian or reptilian eggs, small invertebrates, zebra fish, small plants, seeds, spores, cells or tissues. Cellcult Cassettes contain a small (20-50 ml) rotating cylindrical culture vessel with feed media reservoir, pumps, waste bag and sample collection bags. Cultures can be rotated, perfused, fed, aerated and sampled automatically or on remote command. Fluid Processing Cassettes contain a flexible combination of feed, culture and fixative bags with valves and pumps programmable for various feeding and fixing protocols. Dynacult Cassettes contain a cylindrical bioreactor with differentially rotating walls, pumps and valves for feeding and sampling, and pH and oxygen measurement. All cassettes are doubly contained and are accommodated by a computerized, thermally controlled processing facility, the Advanced Space Experiment Processor, which processes three cassettes, or the Biotechnology Thermal Environment Carrier, which holds up to six cassettes.

Animals↗
PubMed2003

Polymorphisms in the dopamine D4 receptor gene and attention-deficit hyperactivity disorder.

There is considerable evidence to support a role of dopamine-related genes in the molecular aetiology of attention-deficit hyperactivity disorder (ADHD). A 48 bp repeat in exon three of the dopamine D4 receptor gene has been widely studied in clinical ADHD samples, and a meta-analysis of published studies suggests it is associated with ADHD. A number of other polymorphisms across this gene have been characterised but not so thoroughly investigated in relation to ADHD. In this study we have genotyped five polymorphisms (a 120 bp promoter-region duplication, the -616 C/G substitution, the -521 C/T substitution, a poly-G repeat in intron 1, and the 48 bp exon 3 repeat) across the gene in a large clinical sample (n = 188) and their families. We found that none of the markers is individually associated with ADHD, although there is evidence to suggest that a haplotype of markers in the 5' promoter region of the gene (allele 2 of the 120 bp duplication, the C allele of the -616 substitution, and the C allele of the -521 substitution) may confer susceptibility.

Alleles↗
PubMed2003

CHIP: Defining a dimension of the vulnerability to attention deficit hyperactivity disorder (ADHD) using sibling and individual data of children in a community-based sample.

We are taking a quantitative trait approach to the molecular genetic study of attention deficit hyperactivity disorder (ADHD) using a truncated case-control association design. An epidemiological sample of children aged 5 to 15 years was evaluated for symptoms of ADHD using a parent rating scale. Individuals scoring high or low on this scale were selected for further investigation with additional questionnaires and DNA analysis. Data in studies like this are typically complicated. In the study reported on here, individuals have from 1 to 4 questionnaires completed on them and the sample is composed of a mixture of singletons and siblings. In this paper, we describe how we used a genetic hierarchical model to fit our data, together with a twin dataset, in order to estimate genetic factor loadings. Correlation matrices were estimated for our data using a maximum likelihood approach to account for missing data. We describe how we used these results to create a composite score, the heritability of which was estimated to be acceptably high using the twin dataset. This score measures a quantitative dimension onto which molecular genetic data will be mapped.

Adolescent↗
PubMed2003

Right inferior prefrontal cortex mediates response inhibition while mesial prefrontal cortex is responsible for error detection.

Inhibitory control and error detection are among the highest evolved human self-monitoring functions. Attempts in functional neuroimaging to effectively isolate inhibitory motor control from other cognitive functions have met with limited success. Different brain regions in inferior, mesial, and dorsolateral prefrontal cortices and parietal and temporal lobes have been related to inhibitory control in go/no-go and stop tasks. The widespread activation reflects the fact that the designs used so far have comeasured additional noninhibitory cognitive functions such as selective attention, response competition, decision making, target detection, and inhibition failure. Here we use rapid, mixed trial, event-related functional magnetic resonance imaging to correlate brain activation with an extremely difficult situation of inhibitory control in a challenging stop task that controls for noninhibitory functions. The difficulty of the stop task, requiring withholding of a triggered motor response, was assured by an algorithm that adjusted the task individually so that each subject only succeeded on half of all stop trials, failing on the other half. This design allowed to elegantly separate brain activation related to successful motor response inhibition and to inhibition failure or error detection. Brain activation correlating with successful inhibitory control in 20 healthy volunteers could be isolated in right inferior prefrontal cortex. Failure to inhibit was associated with activation in mesial frontopolar and bilateral inferior parietal cortices, presumably reflecting an attention network for error detection.

Adult↗
PubMed2003

A right hemispheric frontocerebellar network for time discrimination of several hundreds of milliseconds.

Debate still surrounds the nature of the role of the dorsolateral prefrontal gyrus (DLPFC) in time perception. This region is frequently associated with working memory and is thus implicated as a so-called "accumulator" within a hypothesized internal clock model. However, we hypothesized that this region may have a more primary role in time perception. To test this hypothesis we used functional magnetic resonance imaging (fMRI) to examine the neural correlates of relatively pure time perception with a temporal discrimination task where intervals of 1 s had to be discriminated from those of 1.3, 1.4, and 1.5 s. Time perception in this particular time domain within the "perceived present" has not previously been investigated using fMRI. By using relatively short time periods to be discriminated and also contrasting activation with an order judgment task, we aimed to minimize the confounding aspects of sustained attention and working memory. In a group of 20 healthy right-handed adult males, neural activation associated with time discrimination was found in a predominantly right hemispheric network of right dorsolateral and inferior prefrontal cortices, right supplementary motor area, and left cerebellum. We conclude that right DLPFC, rather than having a purely working memory function, might be more centrally involved in time perception than previously thought.

Adult↗
PubMed2003

Parental perception of problems and mental health service use for hyperactivity.

OBJECTIVE: To examine predictors of parental perception of hyperactivity as a serious problem and its role in determining the use of specialist mental health services. METHOD: A community sample of 5- to 11-year-old children with pervasive hyperactivity (n = 93) was identified. Children whose parents perceived the hyperactivity as a serious problem were compared with those whose parents did not. Predictors of parental perception of problem and the roles of this and child and parent clinical factors in predicting service use were examined. RESULTS: Controlling for child and parental mental health, the strongest predictor of parental perception of problems was the financial impact of the child's behavior on either parent's work (odds ratio [OR] = 17.43; 95% confidence interval [CI] 3.52-86.40). Other effects on the parent's working ability were also important. Parental perception of problems was the strongest predictor of service use (OR = 9.85; 95% CI 1.42-68.50). CONCLUSIONS: The effects of child behavior difficulties on perceptions of caregivers are multidimensional. The impact of hyperactivity on parents' work and family finances is substantial. Mental health service use is increased if these impacts reach the threshold for the parent to perceive the child's behavior as a problem.

Attention Deficit Disorder with Hyperactivity↗
PubMed2002

Association study of a SNAP-25 microsatellite and attention deficit hyperactivity disorder.

Several lines of evidence implicate synaptosomal-associated protein of 25 kDa (SNAP-25) in the etiology of attention deficit hyperactivity disorder (ADHD). Most notably, the coloboma mouse mutant, considered to be a good animal model of hyperactivity, has a deletion spanning this gene. Introducing a SNAP-25 transgene into these animals alleviates hyperlocomotion. We have identified a novel microsatellite repeat in SNAP-25 located between the 5'UTR and the first coding exon, and tested for association with ADHD. Case-control analyses suggest there may be a role of this polymorphism in ADHD, with one allele over-represented in controls and another over-represented in probands. Within-family tests of linkage and association confirmed these findings. Further work is needed to ascertain the role of SNAP-25 in ADHD and assess the functional significance of this polymorphism.

Alleles↗
PubMed2002

Association of DRD4 in children with ADHD and comorbid conduct problems.

Recent family and twin study findings suggest that ADHD when comorbid with conduct problems may represent a particularly familial and heritable form of ADHD. Although several independent groups have shown association between the DRD4 7 repeat allele and ADHD, others have failed to replicate this finding. Previous TDT analyses of UK and Eire samples had also been negative. We set out to further examine the role of DRD4 but selecting a subgroup of children with ADHD and comorbid conduct problems. Families were recruited from Manchester, Ireland, Birmingham and London clinics. From these, 67 children who fulfilled diagnostic criteria for ADHD and who displayed conduct disorder symptoms were selected. TDT analysis, which had previously yielded negative results for the total sample, showed evidence of association between DRD4 and "ADHD with conduct problems" (7 repeat allele-24 transmissions, 13 non-transmissions; one-tailed P=0.05). These results provide further support for the role of DRD4 in ADHD. Furthermore, these results when considered together with family and twin study findings, suggest that those children with ADHD and comorbid conduct problems may be particularly informative for molecular genetic studies of ADHD. Further work is needed to examine these phenotype issues.

Adolescent↗
PubMed2002

A pilot twin study of psychological measures of attention deficit hyperactivity disorder.

There has been much interest in the genetics of attention deficit hyperactivity disorder and molecular genetic studies are now underway. The success of genetic studies will depend on how well the phenotype is defined. Twin studies using parent and teacher rated questionnaires or interviews all appear to yield highly heritable measures. Nevertheless, there is evidence to suggest that parent measures are subject to rater bias. Consequently there has been much interest in obtaining more objective measures of related traits such as attention span and impulsiveness using, computerised neuropsychological tasks. However there have been few twin studies examining the genetic contribution to these neuropsychological measures. The present study aims to investigate whether performance on the Matching Familiar Figures Test (MFFT) and Continuous Performance Task (CPT) is genetically influenced in childhood. 20 monozygotic (MZ) and 20 dizygotic (DZ) twin pairs were randomly selected from the Greater Manchester Twin Register. Preliminary data suggest that MZ twins perform more similarly than DZ twins on the MFFT, but not the CPT. Future work needs to examine whether other neuropsychological measures commonly used in research on ADHD are genetically influenced using larger twin samples.

Attention↗