Archive for the 'Causes' Category

More on smoking and neuropsych disorders

Published on 13 December 2010 in ADHD, Causes, Comments, Families, News, Research and The press. 0 Comments Tags: , , , , , , , , , , , .

New research shows that using nicotine during pregnancy affects genes involved in myelination and, consequently may help explain why the children of mothers who smoke during pregnancy are more likely to develop such psychiatric disorders as attention deficit hyperactivity disorder, depression, autism, and even drug abuse. In a paper presented at Neuroscience 2010, the annual meeting of the Society for Neuroscience, Professor Ming Li, Ph.D., of the University of Virginia (Charlottesville, VA, US) reported that when rats were given nicotine during pregnancy, their offspring manifested changes in myelin genes for the limbic system, especially the prefrontal cortex, a brain region important for decision-making.

“Our research shows that gestational treatment with nicotine significantly modifies myelin gene expression in specific brain regions that are involved in behavioral processes,” according to Professor Li, leader of the study. “Myelin deficits have been observed in adults with various psychiatric disorders. Our findings suggest that abnormal myelination may contribute to the psychiatric disorders associated with maternal smoking.”
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Preliminary evidence of link between maternal smoking and risk of child problems

Published on 6 December 2010 in ADHD, Causes, Families, News, Research and The press. 0 Comments Tags: , , , .

Researchers from the University of Alabama at Birmingham (AL, US) presented a paper at Neuroscience 2010, the annual meeting of the Society for Neuroscience in which they reported that exposure to nicotine during pregnancy leads to a decrease in adult stem cells and a change in synaptic plasticity in the hippocampus of the offspring. The synaptic changes could have lifelong consequences for the offspring. According to Professor Robin Lester of the Department of Neurobiology and lead researcher on the project, “These problems could include various cognitive deficits, learning difficulties, [and] ADHD.”

These are very preliminary findings. They come from research conducted with rats and will require extensive additional work to make the connections to human learning. Note that the mother rats apparently were also ingesting nicotine while nursing (first 10 days after birth) as well as during pregnancy. My reporting here is based entirely on press releases from UAB and the Society for Neuroscience (with abstract).

Sources: http://www.newswise.com/articles/view/571417/ and http://www.sfn.org/index.aspx?pagename=news_111410b
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A little sugar with your behavior?

Published on 2 November 2010 in ADHD, Causes, News, Research and The press. 0 Comments Tags: , , , , , , , .

Just as I did on EBD Blog, I’m encouraging folks to read Dan Willingham’s blog entry for the Washington Post regarding the persistent myth that sugar causes children to act hyper. Jump right on over to Dan’s post to read his full deflation of this popular balloon, then you can go back and catch my antique take down on the same topic at “Sugar High?”

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ADHD-RD connection confirmed and refined

Published on 28 September 2010 in ADHD, Assessment, Causes, Literacy, News, Research and The press. 3 Comments Tags: , , , .

Writing in Pediatrics, Professor Kouichi Yoshimasu and colleagues reported that the chances of children and youths having reading disabilities is significantly higher among those who have ADHD than it is among the general population of children and youths. Furthermore, although boys are significantly more likely than girls to manifest reading disabilities among the general population, among children and youths with ADHD the chances of reading disabilities are about equal. However, because girls are so much less likely to have reading problems than boys, girls’ risk is much higher in relation to their female peers’ risk.
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Letter-sound correspondences: New scanning data

Published on 15 February 2010 in Causes, Dyslexia, News, Research and The press. 0 Comments Tags: , , , , , , , .

A research team in Professor Leo Blomert’s lab at Maastricht University in the Netherlands reported that brain scans of children with and without dyslexia reveal differences when associating letters with sounds. Vera Blau and colleagues studied 34 9-½-year-old children, 18 of whom were identified as having dyslexia. While the children completed tasks under four different conditions (letters presented only visually; speech sounds presented alone; multi-sensory matching letter–sound pairs; and multi-sensory not-matching letter–sound pairs), the researchers obtained scans of brain activity. They found that in the brains of children with dyslexia there were weaker effects when letters and sounds matched than in the brains of children without dyslexia; these effects appeared most clearly in certain areas of the brain related to language function. In addition, the dyslexic readers’ brains showed weaker activation when speech sounds were the only stimulus (i.e., without accompanying letters).
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The gene DYX1C1 and reading and spelling

Published on 19 November 2009 in Causes, Dyslexia, Families, News and Research. 0 Comments Tags: , , , .

Paul Bates and colleagues have reported new findings about the gene DYX1C1, which has been a focal point for research on genetic contributions to dyslexia for at least six years. Writing for the journal Molecular Psychiatry, the research team revealed that their examination of the relationship between DYX1C1 and variations in reading ability points at certain variations in genes and reading ability. Specific differences in individual nucleotides (single nucleotide polymorphisms, or SNPs), different from those reported previously, appear to be associated with ability and disability in reading and spelling.

The status of DYX1C1 (C15q21.3) as a susceptibility gene for dyslexia is unclear. We report the association of this gene with reading and spelling ability in a sample of adolescent twins and their siblings. Family-based association analyses were carried out on 13 single-nucleotide polymorphisms (SNPs) in DYX1C1, typed in 790 families with up to 5 offspring and tested on 6 validated measures of lexical processing (irregular word) and grapheme–phoneme decoding (pseudo-word) reading- and spelling-based measures of dyslexia, as well as a short-term memory measure. Significant association was observed at the misssense mutation rs17819126 for all reading measures and for spelling of lexical processing words, and at rs3743204 for both irregular and nonword reading. Verbal short-term memory was associated with rs685935. Support for association was not found at rs3743205 and rs61761345 as previously reported by Taipale et al., but these SNPs had very low (0.002 for rs3743205) minor allele frequencies in this sample. These results suggest that DYX1C1 influences reading and spelling ability with additional effects on short-term information storage or rehearsal. Missense mutation rs17819126 is a potential functional basis for the association of DYX1C1 with dyslexia.

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Phonological core in dyslexia

Published on 11 August 2009 in Causes, Dyslexia, News and Research. 2 Comments Tags: , , , , , .

In Archives of Clinical Neuropsychology, Michelle Kibby published the results of a study examining the relationships among measures of short-term memory and dyslexia. In two studies involving children ages 9-13 with and without dyslexia (defined on the basis of discrepancy; > 1 SD difference between IQ and word identification) she found results that are consistent with the theory that the primary problem for children with reading problems is in phonological processing.

The goals of this project were threefold: to determine the nature of the memory deficit in children/adolescents with dyslexia, to utilize clinical memory measures in this endeavor, and to determine the extent to which semantic short-term memory (STM) is related to basic reading performance. Continue reading ‘Phonological core in dyslexia’

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IQ, memory, and reading are hertitable

Published on 15 April 2009 in Causes, Dyslexia, Families, News and Research. 0 Comments Tags: .

In a forthcoming report in Behavioral Genetics, Professor M. van Leeuwen of VU University (Amsterdam, NL) and colleagues reported that the vast majority of variation in children’s reading performance is heritable, with most of the variance in reading attributable to IQ and memory. The researchers studied twins and siblings (only some of whom had reading disabilities), and they measured children’s reading rate, how many times they could correctly tap blocks in a sequence that had just been displayed, the number times the children could correctly recall the location of a part of a visual display (a catepillar in different holes in an apple), repetition of sequences of digits, and IQ.

Figure 3 from van Leeuwen et al.

Before folks begin using this study to argue that there is a simple causal relationship between IQ and reading, please remember three things: (a) this research also implicates memory as an explanatory factor; (b) there are likely other factors that affect IQ, memory, and reading; and (c) even if lots of variance is explained by such factors as IQ and memory, the remaining variance is sufficient to allow fairly substantial instructional effects.

This study investigates the genetic relationship among reading performance, IQ, verbal and visuospatial working memory (WM) and short-term memory (STM) in a sample of 112, 9-year-old twin pairs and their older siblings. The relationship between reading performance and the other traits was explained by a common genetic factor for reading performance, IQ, WM and STM and a genetic factor that only influenced reading performance and verbal memory. Genetic variation explained 83% of the variation in reading performance; most of this genetic variance was explained by variation in IQ and memory performance. We hypothesize, based on these results, that children with reading problems possibly can be divided into three groups: (1) children low in IQ and with reading problems; (2) children with average IQ but a STM deficit and with reading problems; (3) children with low IQ and STM deficits; this group may experience more reading problems than the other two.

van Leeuwen, M. van den Berg, S. M., Peper, J. S., Hulshoff Pol, H. E., & Boomsma, D. I. (2009). Genetic covariance structure of reading, intelligence and memory in children. Behavioral Genetics, [forthcoming].

Link to the PubMed abstract I’ve reproduced here.

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Davis goes on tour

Published on 9 April 2009 in Causes, Dyslexia, Events, Families, News, Research, The press and Treatment. 4 Comments

Ron Davis, whose arguments that dyslexia is something worth having ring hollow and whose claims to have discovered the answer to dyslexia deserve strong challenge, will begin a speaking tour of the US and CA in May. If the lectures are like the public relations materials promoting them and Mr. Davis’ views, they will be heavy on a recounting of his terrific childhood triumphs, when he overcame Autism, taught himself to read, and learned to speak during his late adolescence. He will also provide a first-person account of what it is like to have dyslexia—one is likely to resonate with others’ views—and tout his books, The Gift of Dyslexia and The Gift of Learning, as well as his methods, “Davis Dyslexia Correction®,” “Davis Math Mastery®,” and “Davis Learning Strategies®.”

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Anesthesia and LD

Published on 28 March 2009 in Causes, Families, News, Research and The press. 0 Comments Tags: , .

Cumulative percentage of learning disabilities diagnosis by the age at exposure shown separately for those that have zero, one, or multiple anesthetic exposures before age 4 yr. (Fig 1 from Wilder et al., see sources).

Writing in the academic journal Anesthesiology under the title “Early Exposure to Anesthesia and Learning Disabilities in a Population-based Birth Cohort,” Robert T. Wilder, M.D., and colleagues reported that young children’s exposure to anesthesia was associated with a significant risk for development of Learning Disabilities in children having anesthesia two or more times during early childhood. Although the findings are consistent with analog studies showing that anesthetics affect baby animals’ brain development, they do not necessarily indicate that the drugs caused the children’s LD; one or more other factors could have caused both the need for the surgeries and the LD.

The investigators studied the association between anesthetic exposure before age 4 yr and the development of learning disabilities (LD). A single exposure to anesthesia (n = 449) was not associated with an increased risk of LD (hazard ratio = 1.0, 95% confidence interval [CI], 0.79-1.27). However, children receiving two anesthetics (n = 100) or three or more anesthetics (n = 44) were at increased risk for LD (hazard ratio = 1.59, 95% CI, 1.06-2.37, and hazard ratio = 2.60, 95% CI, 1.60-4.24, respectively). The team noted they cannot determine whether anesthesia itself may contribute to LD, or whether the need for anesthesia is a marker for other unidentified factors that contribute to LD.

In the following video, two of the researchers discuss the project and it’s implications.

Link to the Mayo Clinic press release. Free access to the full article. Hear (or read, or both) Joseph Shapiro’s report on the story for US National Public Radio.

Wilder, R. T., Flick, R. P., Sprung, J., Katusic, S. K., Barbaresi, W. J., Mickelson, C., Gleich, S. J., Schroeder, D. R., Weaver, A. L., & Warner, D. O. (2009). Early exposure to anesthesia and learning disabilities in a population-based birth cohort. Anesthesiology, 110, 796-804.

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