Mixed-handed children more likely to have mental health, language and scholastic problems, study finds

ScienceDaily (Jan. 27, 2010) ? Children who are mixed-handed, or ambidextrous, are more likely to have mental health, language and scholastic problems in childhood than right- or left-handed children, according to a new study published in the journal Pediatrics.

The researchers behind the study, from Imperial College London and other European institutions, suggest that their findings may help teachers and health professionals to identify children who are particularly at risk of developing certain problems.

Around one in every 100 people is mixed-handed. The study looked at nearly 8,000 children, 87 of whom were mixed-handed, and found that mixed-handed 7 and 8-year old children were twice as likely as their right-handed peers to have difficulties with language and to perform poorly in school.

When they reached 15 or 16, mixed-handed adolescents were also at twice the risk of having symptoms of attention deficit/hyperactivity disorder (ADHD). They were also likely to have more severe symptoms of ADHD than their right-handed counterparts. It is estimated that ADHD affects between 3 to 9 percent of school-aged children and young people.

The adolescents also reported having greater difficulties with language than those who were left- or right-handed. This is in line with earlier studies that have linked mixed-handedness with dyslexia.

Little is known about what makes people mixed-handed but it is known that handedness is linked to the hemispheres in the brain. Previous research has shown that where a person's natural preference is for using their right hand, the left hemisphere of their brain is more dominant.

Some researchers have suggested that mixed-handedness indicates that the pattern of dominance is not that which is typically seen in most people, i.e. it is less clear that one hemisphere is dominant over the other. One study has suggested that ADHD is linked to having a weaker function in the right hemisphere of the brain, which could help explain why some of the mixed-handed students in the study had symptoms of ADHD.

Dr Alina Rodriguez, the lead researcher on the study from the School of Public Health at Imperial College London, said: "Mixed-handedness is intriguing -- we don't know why some people prefer to make use of both hands when most people use only one. Our study is interesting because it suggests that some children who are mixed handed experience greater difficulties in school than their left- and right-handed friends. We think that there are differences in the brain that might explain these difficulties, but there needs to be more research.

"Because mixed-handedness is such a rare condition, the number of mixed-handed children we were able to study was relatively small, but our results are statistically and clinically significant. That said, our results should not be taken to mean that all children who are mixed-handed will have problems at school or develop ADHD. We found that mixed-handed children and adolescents were at a higher risk of having certain problems, but we'd like to stress that most of the mixed-handed children we followed didn't have any of these difficulties," added Dr Rodriguez.

To study the effects of mixed-handedness, Dr Rodriguez and her colleagues looked at prospective data from a cohort of 7,871 children from Northern Finland. Using questionnaires, the researchers assessed the children when they reached 7 to 8 years of age and again at 15 to 16 years of age.

When the children were aged 8, the researchers asked parents and teachers to assess their linguistic abilities, scholastic performance and behaviour. The teachers reported whether children had difficulties in reading, writing or mathematics and rated the children's academic performance as below average, average or above average.

The adolescents' parents and the adolescents themselves completed follow-up questionnaires when they were 15-16 years of age, with the children evaluating their school performance in relation to their peers and the parents assessing their children's behaviour, on a questionnaire that is widely used to identify ADHD symptoms.

The research was funded by the Academy of Finland; Sigrid Juselius Foundation, Finland; Thule Institute, University of Oulu, Finland; and the National Institute of Mental Health. Dr Rodriguez received support from VINNMER.

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Imperial College London.

Journal Reference:

Alina Rodriguez, Marika Kaakinen, Irma Moilanen, Anja Taanila, James J. McGough, Sandra Loo, and Marjo-Riitta Jarvelin. Mixed-Handedness Is Linked to Mental Health Problems in Children and Adolescents. Pediatrics, 2010 (in press)

Note: If no author is given, the source is cited instead.

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Children with high blood pressure more likely to have learning disabilities, study finds

ScienceDaily (Nov. 10, 2010) ? Children who have hypertension are much more likely to have learning disabilities than children with normal blood pressure, according to a new University of Rochester Medical Center (URMC) study published in the journal Pediatrics. In fact, when variables such as socio-economic levels are evened out, children with hypertension were four times more likely to have cognitive problems.

"This study also found that children with hypertension are more likely to have ADHD (attention deficit hyperactivity disorder)," said Heather R. Adams, Ph.D., an assistant professor of Neurology and Pediatrics at URMC, and an author of the study. "Although retrospective, this work adds to the growing evidence of an association between hypertension and cognitive function. With 4 percent of children now estimated to have hypertension, the need to understand this potential connection is incredibly important."

Among the study's 201 patients, all of whom had been referred to a pediatric hypertension clinic at URMC's Golisano Children's Hospital, 101 actually had hypertension, or sustained high blood pressure, determined by 24-hour ambulatory monitoring or monitoring by a school nurse or at home. Overall, 18 percent of the children had learning disabilities, well above the general population's rate of 5 percent. But the percentage among those without hypertension was closer to 9 percent, and among those with hypertension, the rate jumped to 28 percent. All of the children were between 10- and 18-years-old, and the children's learning disability and ADHD diagnoses were reported by parents.

This study is part of a series of hypertension studies by Golisano Children's Hospital researchers, led by Principal Investigator Marc Lande, M.D., a pediatric nephrologist, but it was the first that included children with ADHD. Previous studies excluded them because ADHD medications can increase blood pressure. Researchers included them this time because, although it is possible that some of the children's hypertension was caused by medications, it is also possible that the higher rate of ADHD among children with hypertension is a reflection of neurocognitive problems caused by hypertension. Twenty percent of the children with hypertension had ADHD whereas only 7 percent of those without hypertension had ADHD among the study participants. And even when ADHD was factored out of the analyses, there was still a higher rate of learning disabilities in the hypertensive, compared to the non-hypertensive group of children.

"With each study, we're getting closer to understanding the relationship between hypertension and cognitive function in children," Lande said. "And this study underscores the need for us to continue to tease out the potential risk children with hypertension have for learning difficulties at a time when learning is so important. It may be too early to definitively link hypertension and learning disabilities, but it isn't too early for us, as clinicians, to ensure our pediatric patients with hypertension are getting properly screened for cognitive issues."

The study was funded by a grant from the National Institutes of Health. The authors have no conflicts to disclose.

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Rochester Medical Center.

Journal Reference:

H. R. Adams, P. G. Szilagyi, L. Gebhardt, M. B. Lande. Learning and Attention Problems Among Children With Pediatric Primary Hypertension. Pediatrics, 2010; DOI: 10.1542/peds.2010-1899

Note: If no author is given, the source is cited instead.

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Learning Disabilities More Likely In Children With High Blood Pressure

Main Category: Hypertension
Also Included In: Pediatrics / Children's Health;??ADHD;??Psychology / Psychiatry
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Children who have hypertension are much more likely to have learning disabilities than children with normal blood pressure, according to a new University of Rochester Medical Center (URMC) study published this week in the journal, Pediatrics. In fact, when variables such as socio-economic levels are evened out, children with hypertension were four times more likely to have cognitive problems.

"This study also found that children with hypertension are more likely to have ADHD (attention deficit hyperactivity disorder)," said Heather R. Adams, Ph.D., an assistant professor of Neurology and Pediatrics at URMC, and an author of the study. "Although retrospective, this work adds to the growing evidence of an association between hypertension and cognitive function. With 4 percent of children now estimated to have hypertension, the need to understand this potential connection is incredibly important."

Among the study's 201 patients, all of whom had been referred to a pediatric hypertension clinic at URMC's Golisano Children's Hospital, 101 actually had hypertension, or sustained high blood pressure, determined by 24-hour ambulatory monitoring or monitoring by a school nurse or at home. Overall, 18 percent of the children had learning disabilities, well above the general population's rate of 5 percent. But the percentage among those without hypertension was closer to 9 percent, and among those with hypertension, the rate jumped to 28 percent. All of the children were between 10- and 18-years-old, and the children's learning disability and ADHD diagnoses were reported by parents.

This study is part of a series of hypertension studies by Golisano Children's Hospital researchers, led by Principal Investigator Marc Lande, M.D., a pediatric nephrologist, but it was the first that included children with ADHD. Previous studies excluded them because ADHD medications can increase blood pressure. Researchers included them this time because, although it is possible that some of the children's hypertension was caused by medications, it is also possible that the higher rate of ADHD among children with hypertension is a reflection of neurocognitive problems caused by hypertension. Twenty percent of the children with hypertension had ADHD whereas only 7 percent of those without hypertension had ADHD among the study participants. And even when ADHD was factored out of the analyses, there was still a higher rate of learning disabilities in the hypertensive, compared to the non-hypertensive group of children.

"With each study, we're getting closer to understanding the relationship between hypertension and cognitive function in children," Lande said. "And this study underscores the need for us to continue to tease out the potential risk children with hypertension have for learning difficulties at a time when learning is so important. It may be too early to definitively link hypertension and learning disabilities, but it isn't too early for us, as clinicians, to ensure our pediatric patients with hypertension are getting properly screened for cognitive issues."

The study was funded by a grant from the National Institutes of Health. The authors have no conflicts to disclose.

Source:
Heather Hare
University of Rochester Medical Center

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First direct evidence that ADHD is a genetic disorder: Children with ADHD more likely to have missing or duplicated segments of DNA

ScienceDaily (Sep. 30, 2010) ? New research provides the first direct evidence that attention-deficit/hyperactivity disorder (ADHD) is a genetic condition. Scientists at Cardiff University found that children with ADHD were more likely to have small segments of their DNA duplicated or missing than other children.

The study also found significant overlap between these segments, known as copy number variants (CNVs), and genetic variants implicated in autism and schizophrenia, proving strong evidence that ADHD is a neurodevelopmental disorder -- in other words, that the brains of children with the disorder differ from those of other children.

The research, published in the journal The Lancet, was largely funded by the Wellcome Trust, with additional support from Action Medical Research, the Medical Research Council and the European Union.

"We hope that these findings will help overcome the stigma associated with ADHD," says Professor Anita Thapar. "Too often, people dismiss ADHD as being down to bad parenting or poor diet. As a clinician, it was clear to me that this was unlikely to be the case. Now we can say with confidence that ADHD is a genetic disease and that the brains of children with this condition develop differently to those of other children."

ADHD is one of the most common mental health disorders in childhood, affecting around one in 50 children in the UK. Children with ADHD are excessively restless, impulsive and distractible, and experience difficulties at home and in school. Although no cure exists for the condition, symptoms can be reduced by a combination of medication and behavioural therapy.

The condition is highly heritable -- children with ADHD are statistically more likely to also have a parent with the condition and a child with an identical twin with ADHD has a three in four chance of also having the condition. Even so, until now there has been no direct evidence that the condition is genetic and there has been much controversy surrounding its causes, which some people have put down to poor parenting skills or a sugar-rich diet.

The team at Cardiff University analysed the genomes of 366 children, all of whom had been given a clinical diagnosis of ADHD, against over 1,000 control samples in search of variations in their genetic make-up that were more common in children with the condition.

"Children with ADHD have a significantly higher rate of missing or duplicated DNA segments compared to other children and we have seen a clear genetic link between these segments and other brain disorders," explains Dr Nigel Williams. "These findings give us tantalising clues to the changes that can lead to ADHD."

The researchers found that rare CNVs were almost twice as common in children with ADHD compared to the control sample -- and even higher for children with learning difficulties. CNVs are particularly common in disorders of the brain.

There was also significant overlap between CNVs identified in children with ADHD and regions of the genome which are known to influence susceptibility to autism and schizophrenia. Whilst these disorders are currently thought to be entirely separate, there is some overlap between ADHD and autism in terms of symptoms and learning difficulties. This new research suggests there may be a shared biological basis to the two conditions.

The most significant overlap was found at a particular region on chromosome 16 which has been previously implicated in schizophrenia and other major psychiatric disorders and spans a number of genes including one known to play a role in the development of the brain .

"ADHD is not caused by a single genetic change, but is likely caused by a number of genetic changes, including CNVs, interacting with a child's environment," explains Dr Kate Langley. "Screening children for the CNVs that we have identified will not help diagnose their condition. We already have very rigorous clinical assessments to do just that."

Dr John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, which has supported Professor Thapar's work for ten years, says: "These findings are testament to the perseverance of Professor Thapar and colleagues to prove the often unfashionable theory that ADHD is a brain disorder with genetic links. Using leading-edge technology, they have begun to shed light on the causes of what is a complex and often distressing disorder for both the children and their families."

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Wellcome Trust, via EurekAlert!, a service of AAAS.

Journal Reference:

Nigel M Williams, Irina Zaharieva, Andrew Martin, Kate Langley, Kiran Mantripragada, Ragnheidur Fossdal, Hreinn Stefansson, Kari Stefansson, Pall Magnusson, Olafur O Gudmundsson, Omar Gustafsson, Peter Holmans, Michael J Owen, Michael O'Donovan, Anita Thapar. Rare chromosomal deletions and duplications in attention-deficit hyperactivity disorder: a genome-wide analysis. Lancet, 2010; DOI: 10.1016/S0140-6736(10)61109-9

Note: If no author is given, the source is cited instead.

View the original article here