201 research outputs found
Supporting Licensed Science Teachers’ Professional Development in Adopting Learner-Centred Pedagogy in Tanzanian Secondary Schools
No full textThe purpose of this study was to obtain a better understanding of the professional learning needs of Tanzanian science teachers who were recruited using an alternative route approach to teacher recruitment and to seek ways to address these needs. The alternative route to teacher recruitment usually refers (but not always) to the enlistment of university graduates, who are trained in a non-accredited teacher education programme, and then licensed or certified to teach in schools. In Tanzania teachers trained in this way are referred to as ‘licensed teachers’. This study first identified the licensed teachers’ professional learning needs in relation to pedagogical content knowledge (PCK) by examining their effectiveness in using learner-centred teaching methods in the classroom. The findings from this first phase of the investigation revealed that the licensed science teachers rarely used learner-centred strategies and their PCK was underdeveloped in this area. In the second phase of the study a professional development intervention (PDI) was developed and implemented to enhance the licensed science teachers’ PCK and improve their classroom teaching practices.
This study used a multiple case study approach underpinned by an interpretive research paradigm. The study adopted the situativity theory to inform the professional development intervention, with the view that teachers’ learning and knowing are situated in and influenced by the physical and social context and participation in authentic activity as a community of learners. The participants of this study were six licensed teachers, twenty four students and five education officials. Data were collected from multiple sources such as classroom observations, one-to-one semi-structured interviews, focus group discussions, documentary reviews and teachers’ reflective notes. The data were analysed thematically using the five components of PCK identified by Magnusson, Krajcik, and Borko (1999), as the analytical framework.
The results from the first phase of investigation showed that the licensed science teachers had underdeveloped PCK and did not use/understand learner-centred teaching methods. Instead their classroom teaching practices were dominated by teacher-centred teaching methods and they lacked the skills of preparing learner-centred science lessons. Also tests and examinations prepared by the licensed science teachers were found to be mostly testing the lower levels of Bloom’s knowledge taxonomy, that is, knowledge, comprehension and application, with few items relating to analysis. The evaluation of the PDI indicated that it had a positive impact on licensed science teachers’ PCK, with the licensed teachers showing improved classroom teaching practices after the PDI. Students’ learning was enhanced as a direct result of licensed science teachers’ improvement in their ability to design and teach lesson using learner-centred teaching methods.
This study has implications for teacher education practice and students’ learning in countries using an alternative approach to teacher recruitment and for educational research. This thesis offers suggestions for reform in teacher education institutions, policy and practice and for further research into how to improve this form of alternative route to teacher recruitment. The most significant of these suggestions is the setting up of PLCs of teachers with on-going expert support and school leadership (headmasters/mistresses, district educational officers) involvement. This on-site structure for sustained, supported professional learning offers a way forward for improving PCK of many untrained licensed teachers currently working in Tanzanian rural community secondary schools. The thesis concludes that unqualified licensed science teachers working in schools need school-based professional development support to enhance their underdeveloped PCK, since students taught by licensed teachers are unlikely to be receiving the levels of knowledge and skills potentially needed to compete in the global economy
Conduct disorder and ADHD: evaluation of conduct problems as a categorial and quantitative trait in the international multicentre ADHD genetics study (In special issue: Special Issue on the Genetics of ADHD Dedicated to the Memory of Richard Todd)
No full textAttention-deficit/hyperactivity disorder (ADHD) is typically characterized by inattention, excessive motor activity, impulsivity, and distractibility. Individuals with ADHD have significant impairment in family and peer relations, academic functioning, and show high co-morbidity with a wide range of psychiatric disorders including oppositional defiant disorder (ODD), conduct disorder (CD), anxiety disorder, depression, substance abuse, and pervasive developmental disorder (PDD). Family studies suggest that ADHD + CD represents a specific subtype of the ADHD disorder with familial risk factors only partly overlapping with those of ADHD alone. We performed a hypothesis-free analysis of the GAIN-ADHD sample to identify markers and genes important in the development of conduct problems in a European cohort of individuals with ADHD. Using the Family-Based Association Test (FBAT) package we examined three measures of conduct problems in 1,043,963 autosomal markers. This study is part of a series of exploratory analyses to identify candidate genes that may be important in ADHD and ADHD-related traits, such as conduct problems. We did not find genome-wide statistical significance (P < 5 × 10-7) for any of the tested markers and the three conduct problem traits. Fifty-four markers reached strong GWA signals (P < 10-5). We discuss these findings in the context of putative candidate genes and the implications of these findings in the understanding of the etiology of ADHD + CD. We aimed to achieve insight into the genetic etiology of a trait using a hypothesis-free study design and were able to identify a number of biologically interesting markers and genes for follow-up studies
Home environment: association with hyperactivity/impulsivity in children with ADHD and their non-ADHD siblings.
No full textWe wished to ascertain if there is an association between symptoms of attention-deficit/hyperactivity disorder (ADHD) and home environment in children with ADHD and non-ADHD siblings, controlling for other environmental measures.
METHODS:
96 children with ADHD combined type (ADHD-CT) and their siblings participated in the study. Parent and teacher Conners\u27 rating scales were completed and home environment was assessed using the middle childhood and early adolescent Home Observation for Measurement of the Environment (HOME). ADHD symptoms were assessed for correlation with HOME in children with ADHD-CT and non-ADHD siblings and multiple regression analysis was used to control for gender, socio-economic status, exposure to nicotine, exposure to alcohol in utero, birth weight, gestational age, pregnancy and perinatal risk factors. The presence of oppositional disorders was assessed for association with HOME score in those with ADHD-CT. The multiple regression analysis was repeated controlling for environmental factors and for oppositional disorders in those with ADHD-CT. Oppositional symptoms were assessed for correlation with HOME score in non-ADHD siblings.
RESULTS:
Teacher-rated hyperactive/impulsive scores correlated with HOME (r=-0.27, P < 0.01) in children with ADHD-CT. This association remained significant when other environmental factors and oppositional disorders were controlled for. Environmental factors and gender contributed to 30% of the variance of ADHD symptoms in ADHD-CT. Parent-rated hyperactive/impulsive scores also correlated with HOME (r=-0.28, P < 0.05) for non-ADHD siblings. An association between HOME and diagnosis of oppositional defiant disorder or conduct disorder was found for children with ADHD-CT and between HOME and oppositional symptoms in non-ADHD siblings.
CONCLUSIONS:
The home environment has a small but significant association with hyperactive/impulsive symptoms in children with ADHD-CT and non-ADHD siblings. This association remained when other environmental factors were taken into account. Oppositional symptoms are associated with home environment in ADHD-CT and in non-ADHD siblings
Using the R Package crlmm for Genotyping and Copy Number Estimation
No full textGenotyping platforms such as Affymetrix can be used to assess genotype-phenotype as well as copy number-phenotype associations at millions of markers. While genotyping algorithms are largely concordant when assessed on HapMap samples, tools to assess copy number changes are more variable and often discordant. One explanation for the discordance is that copy number estimates are susceptible to systematic differences between groups of samples that were processed at different times or by different labs. Analysis algorithms that do not adjust for batch effects are prone to spurious measures of association. The R package crlmm implements a multilevel model that adjusts for batch effects and provides allele-specific estimates of copy number. This paper illustrates a workflow for the estimation of allele-specific copy number and integration of the marker-level estimates with complimentary Bioconductor software for inferring regions of copy number gain or loss. All analyses are performed in the statistical environment R.
Relationship between cognitive abilities and mental health as represented by cognitive abilities at the neural and genetic levels of analysis
No full textCognitive abilities are closely tied to mental health from early childhood. This study explores how neurobiological units of analysis of cognitive abilities—multimodal neuroimaging and polygenic scores (PGS)—represent this connection. Using data from over 11,000 children (ages 9–10) in the Adolescent Brain Cognitive Development (ABCD) Study, we applied multivariate models to predict cognitive abilities from mental health, neuroimaging, PGS, and environmental factors. Neuroimaging included 45 MRI-derived features (e.g. task/resting-state fMRI, structural MRI, diffusion imaging). Environmental factors encompassed socio-demographics (e.g. parental income/education), lifestyle (e.g. sleep, extracurricular activities), and developmental adverse events (e.g. parental use of alcohol/tobacco, pregnancy complications). Cognitive abilities were predicted by mental health (r = 0.36), neuroimaging (r = 0.54), PGS (r = 0.25), and environmental factors (r = 0.49). Commonality analyses showed that neuroimaging (66%) and PGS (21%) explained most of the cognitive–mental health link. Environmental factors accounted for 63% of the cognitive–mental health link, with neuroimaging and PGS explaining 58% and 21% of this environmental contribution, respectively. These patterns remained consistent over two years. Findings highlight the importance of neurobiological units of analysis for cognitive abilities in understanding the cognitive–mental health connection and its overlap with environmental factors
Relationship between cognitive abilities and mental health as represented by cognitive abilities at the neural and genetic levels of analysis
No full textCognitive abilities are closely tied to mental health from early childhood. This study explores how neurobiological units of analysis of cognitive abilities—multimodal neuroimaging and polygenic scores (PGS)—represent this connection. Using data from over 11,000 children (ages 9–10) in the Adolescent Brain Cognitive Development (ABCD) Study, we applied multivariate models to predict cognitive abilities from mental health, neuroimaging, PGS, and environmental factors. Neuroimaging included 45 MRI-derived features (e.g. task/resting-state fMRI, structural MRI, diffusion imaging). Environmental factors encompassed socio-demographics (e.g. parental income/education), lifestyle (e.g. sleep, extracurricular activities), and developmental adverse events (e.g. parental use of alcohol/tobacco, pregnancy complications). Cognitive abilities were predicted by mental health (r = 0.36), neuroimaging (r = 0.54), PGS (r = 0.25), and environmental factors (r = 0.49). Commonality analyses showed that neuroimaging (66%) and PGS (21%) explained most of the cognitive–mental health link. Environmental factors accounted for 63% of the cognitive–mental health link, with neuroimaging and PGS explaining 58% and 21% of this environmental contribution, respectively. These patterns remained consistent over two years. Findings highlight the importance of neurobiological units of analysis for cognitive abilities in understanding the cognitive–mental health connection and its overlap with environmental factors
ADHD and DAT1: further evidence of paternal over-transmission of risk alleles and haplotype
No full textWe [Hawi et al. (2005); Am J Hum Genet 77:958-965] reported paternal over-transmission of risk alleles in some ADHD-associated genes. This was particularly clear in the case of the DAT1 3-UTR VNTR. In the current investigation, we analyzed three new sample comprising of 1,248 ADHD nuclear families to examine the allelic over-transmission of DAT1 in ADHD. The IMAGE sample, the largest of the three-replication samples, provides strong support for a parent of origin effect for allele 6 and the 10 repeat allele (intron 8 and 3-UTR VNTR, respectively) of DAT1. In addition, a similar pattern of over-transmission of paternal risk haplotypes (constructed from the above alleles) was also observed. Some support is also derived from the two smaller samples although neither is independently significant. Although the mechanism driving the paternal over-transmission of the DAT risk alleles is not known, these finding provide further support for this phenomenon
Functional analysis of intron 8 and 3' UTR variable number of tandem repeats of SLC6A3: Differential activity of intron 8 variants
No full textAssociation studies have found that variation in the dopamine transporter gene (SLC6A3) is important in the susceptibility to attention-deficit hyperactivity disorder (ADHD) and response to methylphenidate treatment. An understanding of the biological mechanisms underlying these associations is still inconclusive. We assessed the relative activity of variable number tandem repeat (VNTR) alleles of SLC6A3 under basal and stimulated cellular conditions, as well as in the presence of pharmacological blockade of the dopamine transporter using gene-reporter constructs. The intron 8 VNTR 5-repeat allele is more active than the 6-repeat allele. In the presence of forskolin, both alleles were significantly induced. Blockade of the dopamine transporter did not influence activity of either allelic construct. No difference in activity between 9-and 10-repeat alleles of the 3′-untranslated region VNTR was observed under any experimental condition. These data suggest that the intron 8 VNTR is a functional variant with an ADHD susceptibility allele having reduced activity. The lack of enhanced allele-specific activity in response to treatment regimes suggests that differential activity under basal conditions is the primary mode of action
The influence of serotonin and other genes on impulsive behavioral aggression and cognitive impulsivity in children with attention-deficit/hyperactivity disorder (ADHD): findings from a family-based association test (FVAT) analysis
No full textBackground: Low serotonergic (5-HT) activity correlates with increased impulsive-aggressive
behavior, while the opposite association may apply to cognitive impulsiveness. Both types of
impulsivity are associated with attention-deficit/hyperactivity disorder (ADHD), and genes of
functional significance for the 5-HT system are implicated in this disorder. Here we demonstrate
the separation of aggressive and cognitive components of impulsivity from symptom ratings and test their association with 5-HT and functionally related genes using a family-based association test
(FBAT-PC).Methods: Our sample consisted of 1180 offspring from 607 families from the International
Multicenter ADHD Genetics (IMAGE) study. Impulsive symptoms were assessed using the long
forms of the Conners and the Strengths and Difficulties parent and teacher questionnaires. Factor
analysis showed that the symptoms aggregated into parent- and teacher-rated behavioral and
cognitive impulsivity. We then selected 582 single nucleotide polymorphisms (SNPs) from 14 genes
directly or indirectly related to 5-HT function. Associations between these SNPs and the
behavioral/cognitive groupings of impulsive symptoms were evaluated using the FBAT-PC
approach.Results: In the FBAT-PC analysis for cognitive impulsivity 2 SNPs from the gene encoding
phenylethanolamine N-methyltransferase (PNMT, the rate-limiting enzyme for adrenalin synthesis)
attained corrected gene-wide significance. Nominal significance was shown for 12 SNPs from
BDNF, DRD1, HTR1E, HTR2A, HTR3B, DAT1/SLC6A3, and TPH2 genes replicating reported
associations with ADHD. For overt aggressive impulsivity nominal significance was shown for 6
SNPs from BDNF, DRD4, HTR1E, PNMT, and TPH2 genes that have also been reported to be
associated with ADHD. Associations for cognitive impulsivity with a SERT/SLC6A4 variant (STin2:
12 repeats) and aggressive behavioral impulsivity with a DRD4 variant (exon 3: 3 repeats) are also
described.Discussion: A genetic influence on monoaminergic involvement in impulsivity shown by children
with ADHD was found. There were trends for separate and overlapping influences on impulsiveaggressive
behavior and cognitive impulsivity, where an association with PNMT (and arousal
mechanisms affected by its activity) was more clearly involved in the latter. Serotonergic and
dopaminergic mechanisms were implicated in both forms of impulsivity with a wider range of
serotonergic mechanisms (each with a small effect) potentially influencing cognitive impulsivity.
These preliminary results should be followed up with an examination of environmental influences
and associations with performance on tests of impulsivity in the laboratory
Does parental expressed emotion moderate genetic effects in ADHD? An exploration using a genome wide association scan
No full textStudies of gene × environment (G × E) interaction in ADHD have previously focused on known risk genes for ADHD and environmentally mediated biological risk. Here we use G × E analysis in the context of a genome-wide association scan to identify novel genes whose effects on ADHD symptoms and comorbid conduct disorder are moderated by high maternal expressed emotion (EE). SNPs (600,000) were genotyped in 958 ADHD proband-parent trios. After applying data cleaning procedures we examined 429,981 autosomal SNPs in 909 family trios. ADHD symptom severity and comorbid conduct disorder was measured using the Parental Account of Childhood Symptoms interview. Maternal criticism and warmth (i.e., EE) were coded by independent observers on comments made during the interview. No G × E interactions reached genome-wide significance. Nominal effects were found both with and without genetic main effects. For those with genetic main effects 36 uncorrected interaction P-values were <10-5 implicating both novel genes as well as some previously supported candidates. These were found equally often for all of the interactions being investigated. The observed interactions in SLC1A1 and NRG3 SNPs represent reasonable candidate genes for further investigation given their previous association with several psychiatric illnesses. We find evidence for the role of EE in moderating the effects of genes on ADHD severity and comorbid conduct disorder, implicating both novel and established candidates. These findings need replicating in larger independent samples
- …
