Learning problems

Poverty affects brain development through attention needs

December, 2012

One reason for the association between poverty and poorer cognition in children may lie in how poverty affects attention, with poor children tending to use more cognitive resources in monitoring the environment.

There have been a number of studies in the past few years showing how poverty affects brain development and function. One of these showed specifically that children of high and low socioeconomic status showed differences in brain wave patterns associated with an auditory selective attention task. This was thought to indicate that the groups were using different mechanisms to carry out the task, with the lower SES children employing extra resources to attend to irrelevant information.

In a follow-up study, 28 young adolescents (12-14 years) from two schools in neighborhoods of different socioeconomic status answered questions about their emotional and motivational state at various points during the day, and provided saliva samples to enable monitoring of cortisol levels. At one point in the afternoon, they also had their brainwaves monitored while they carried out an auditory selective attention task (hearing different sounds played simultaneously into both ears, they were required to press a button as fast as possible when they heard one particular sound).

While performance on the task was the same for both groups, there were, once again, differences in the brain wave patterns. Higher SES children exhibited far larger theta waves in the frontal lobes in response to sounds they attended to than to compared to those they should have ignored, while lower SES children showed much larger theta waves to the unattended sounds than for the attended sounds.

While the lower SES children had higher cortisol levels throughout the school day, like the higher SES children, they showed little change around the task, suggesting neither group was particularly stressed by the task. Both groups also showed similar levels of boredom and motivation.

What the findings suggest is that lower SES children have to exert more cognitive control to avoid attending to irrelevant stimuli than higher SES children — perhaps because they live in more threatening environments.

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Sensory therapy contraindicated for autism

December, 2012

A review has concluded that there is no evidence that sensory integration therapy helps autistic children.

A review of 25 major studies investigating the value of sensory integration therapy (SIT) for autistic children has concluded that this most popular of therapies has no scientific support.

Only three of the 25 studies found benefits from SIT, and these three all had serious methodological flaws. Eight of the studies found mixed results, while 14 studies reported no benefits. Many of the reviewed studies had serious methodological flaws.

It has been suggested that SIT may even be harmful, in that it may lead to an increase in undesirable behavior. Regardless, by taking up time that could otherwise be spent on effective therapies, the use of SIT is not recommended.

The only scientifically valid treatment and intervention for individuals on the autism spectrum is said to be applied behavior analysis, in which, unfortunately, few are trained. With applied behavior analysis, the therapist teaches children age-appropriate skills and offers systematic, repetitious positive reinforcement for desired behaviors.

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Autism therapy can normalize face processing

November, 2012

A small study shows that an intensive program to help young children with autism not only improves cognition and behavior, but can also normalize brain activity for face processing.

The importance of early diagnosis for autism spectrum disorder has been highlighted by a recent study demonstrating the value of an educational program for toddlers with ASD.

The study involved 48 toddlers (18-30 months) diagnosed with autism and age-matched normally developing controls. Those with ASD were randomly assigned to participate in a two-year program called the Early Start Denver Model, or a standard community program.

The ESDM program involved two-hour sessions by trained therapists twice a day, five days every week. Parent training also enabled ESDM strategies to be used during daily activities. The program emphasizes interpersonal exchange, social attention, and shared engagement. It also includes training in face recognition, using individualized booklets of color photos of the faces of four familiar people.

The community program involved evaluation and advice, annual follow-up sessions, programs at Birth-to-Three centers and individual speech-language therapy, occupational therapy, and/or applied behavior analysis treatments.

All of those in the ESDM program were still participating at the end of the two years, compared to 88% of the community program participants.

At the end of the program, children were assessed on various cognitive and behavioral measures, as well as brain activity.

Compared with children who participated in the community program, children who received ESDM showed significant improvements in IQ, language, adaptive behavior, and autism diagnosis. Average verbal IQ for the ESDM group was 95 compared to an average 75 for the community group, and 93 vs 80 for nonverbal IQ. These are dramatically large differences, although it must be noted that individual variability was high.

Moreover, for the ESDM group, brain activity in response to faces was similar to that of normally-developing children, while the community group showed the pattern typical of autism (greater activity in response to objects compared to faces). This was associated with improvements in social behavior.

Again, there were significant individual differences. Specifically, 73% of the ESDM group, 53% of the control group, and 29% of the community group, showed a pattern of faster response to faces. (Bear in mind, re the control group, that these children are all still quite young.) It should also be borne in mind that it was difficult to get usable EEG data from many of the children with ASD — these results come from only 60% of the children with ASD.

Nevertheless, the findings are encouraging for parents looking to help their children.

It should also be noted that, although obviously earlier is better, the findings don’t rule out benefits for older children or even adults. Relatively brief targeted training in face recognition has been shown to affect brain activity patterns in adults with ASD.

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Video games and impaired attention: a vicious circle

April, 2012

A large, long-running study suggests both that children with attention difficulties tend to spend more time playing video games, and that extensive video game playing is bad for attention.

A three-year study involving 3,034 Singaporean children and adolescents (aged 8-17) has found that those who spent more time playing video games subsequently had more attention problems, even when earlier attention problems, sex, age, race, and socioeconomic status were statistically controlled. Those who were more impulsive or had more attention problems subsequently spent more time playing video games, even when initial video game playing was statistically controlled. These findings suggest that the cause-effect relationship between video game playing and attention problems/impulsiveness goes both ways.

While the particular content may have an effect on attention problems and impulsiveness (violent games appeared to be an additional, independent, factor in attention problems), it was the total time spent that was more important.

Participants completed questionnaires about their video game playing habits annually for three years running. They also completed questionnaires aimed to measure attention and impulsiveness (the Current ADHD Symptoms Scale Self-Report, and the Barratt Impulsiveness Scale-11, respectively). Regarding attention, the children answered questions such as how often they "fail to give close attention to details or make careless mistakes" in their work or "blurt out answers before questions have been completed." For the impulsivity test, they selected points they felt described themselves, such as "I often make things worse because I act without thinking" or "I concentrate easily."

How does this finding relate to other evidence showing that playing video games can improve visual attention for rapid and accurate recognition of information from the environment? The answer lies in the different nature of attention — the attention needed for visual search differs in important ways from the attention necessary for sustained concentration in contexts that are often effortful and/or boring.

The example of many attention-challenged individuals makes this more understandable. Many parents of children with ADHD find that the only thing their child can concentrate on for a lengthy period is video games. The answer to that riddle is the rapidly changing nature of video games, and the way they are designed to grab the attention, with flashing lights and loud noises and moving images etc. The young person is not, therefore, improving their ability to focus in a way that is helpful for the school environment, or indeed for everyday life.

Unfortunately, this study suggests that it is precisely those people who are most in need of such ‘external supports’ for attention (‘grabbing’ stimuli such as lights and sounds and movement) — that is, those individuals who are least able to control their own attention — who are most likely to spend a lot of time playing such games. The games then weaken their attentional control even more, and so the cycle continues.

So this research answers the question ADHD parents tend to have: should I encourage my child to play video games a lot (given that it’s the only thing that holds their attention) or not? The answer, unfortunately, would seem to be: not. However, all is not lost. There are computer ‘games’ that are designed to help those with ADHD learn to concentrate in a way that is more useful (see the Topic collection on ADHD for more on this).

The American Academy of Pediatrics recommends one hour per day of total media screen time (including TV, DVDs, video games, Internet, iPad, etc.) for children in elementary school, and two hours for children in secondary school.

Reference: 

Gentile, D.A., Swing, E.L., Lim, C.G. & Khoo, A. 2012. Video game playing, attention problems, and impulsiveness: Evidence of bidirectional causality. Psychology of Popular Media Culture, Vol 1(1), Jan 2012, 62-70. doi: 10.1037/a0026969

Full text available at http://www.apa.org/pubs/journals/releases/ppm-1-1-62.pdf

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Long-lasting effects of early-childhood brain injuries

January, 2012

A 10 year follow-up of children hospitalized for brain injuries in early childhood suggests that young brains are not as resilient as we thought.

I recently discussed some of the implications of head injuries and how even mild concussions can have serious and long-term consequences. A follow-up study looking at the effects of childhood traumatic brain injury ten years after the event has found that even those with mild TBI showed some measurable effects, while those with severe TBI had markedly poorer performance on a number of cognitive measures.

The study involved 40 children who were admitted to hospital with TBI in early childhood (between 2 to 7 years; average just under 5), and 16 healthy controls. The children’s cognitive functions were assessed at the time of accident, and again at 12 and 30 months and 10 years later. Of the 40 with TBIs, 7 had mild injuries, 20 had moderate, and 13 severe.

Unsurprisingly, children with severe TBI had the poorest outcomes. This group was significantly poorer (compared to controls) on full scale IQ; performance IQ; verbal IQ; verbal comprehension; perceptual organization, processing speed. Those who had moderate TBI were significantly poorer on full scale IQ and verbal comprehension only, and those with mild TBI performed more poorly than the controls on verbal comprehension only. Note the size of these effects: the average scores of the group with severe TBI were 18-26 points lower than the control group. In comparison, those with moderate TBI were around 10 points lower on the two significant measures.

These findings are in contrast to research involving adults and older children, where IQ tends to remain intact.

They also contradict the belief that young brains have greater ability to ‘bounce back’ from injury.

Interestingly, the recovery trajectory wasn’t significantly affected by severity of injury — all the groups followed a similar pattern and they all tended to plateau from 5 to 10 years after injury. In general, the findings paint a picture of a long period of disrupted development immediately after the injury, lasting perhaps as long as 30 months, before the brain has recovered sufficiently to progress relatively normally. In other words, intervention may be helpful even years after the injury.

One weakness in the study is the small number of mild TBI cases. It should also be noted that the IQ of the control group was surprisingly high (113). However, given that they had similar IQ levels to the TBI groups prior to injury, it is possible that this reflects a practice effect (but remember that all groups got the same amount of practice).

One thing I wonder about, given recent research pointing to the value of schooling in raising IQ, is the extent to which some of this is due to loss of education that may have resulted from severe injury.

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Bilingualism doesn't hamper language abilities of children with autism

November, 2011

Two studies demonstrate that language development in young children with ASD is the same in those raised in a multilingual environment as in those raised with only one language.

Bilingual parents of children with autism spectrum disorder often decide to speak only one language around their child because of advice from child development professionals who believe that exposure to two languages might further limit the child’s communication skills. Two recent studies challenge that assumption.

One study tested the vocabulary size of 14 bilingual (English-Mandarin/Cantonese) and 14 English-monolingual young children with ASD (aged 3-6). Bilingual children had a larger total vocabulary than monolingual children. When translation equivalents (two words in each language with the same meaning) were counted only once, the vocabularies of both bilingual and monolingual children were not significantly different. Both groups had equivalent scores on all but one measure of language and vocabulary, including English production vocabulary, conceptual production vocabulary, and vocabulary comprehension.

The second Canadian study found similar results in a slightly larger group of children (45 bilingual and 30 monolingual children with an average age of around 5). Languages covered were diverse: French, English, Chinese, Farsi, Hebrew, Italian, Romanian, Spanish and Tamil. Bilingual children were divided into those who were exposed to both languages from infancy, and those who were exposed later (the cut-off was 12 months, but in general changes in the language environment occurred much later: on average, children in the former group were bilingually-exposed for the first 25 months; children in the latter group were monolingually-exposed for the first 31 months). Eleven children were trilingual. In order not to introduce sampler bias, non-verbal children were not excluded — seven participants spoke fewer than 10 words, of whom two were nonverbal.

There were no significant differences between the three groups at a language level, although monolingual and bilingual children exposed from infancy consistently scored higher than bilingual children exposed from a later age. Also, children exposed to two or more languages from infancy scored significantly higher than both groups on social interaction, and those exposed later were worst of the three groups. These differences probably reflect various social variables underlying the different language experiences.

The main reason for the belief that autistic children are better not ‘burdened’ with an additional language is because of their language difficulties. These studies are not saying that a child with ASD raised in two languages will be equally fluent with both. In the second study, second language vocabularies were much smaller than their dominant language vocabularies. But that’s not the point. Whether or not there is any general cognitive advantage in bilingualism for this group, as there is for normally-developing children, remains to be determined. But there is a clear message that parents of ASD children can take on board: if your family is bilingual, relax and enjoy interacting with your ASD child in your language of choice.

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Prenatal exposure to common insecticide linked to lower IQ at age 7

May, 2011

Two longitudinal studies, one rural and one urban, have reported an association between prenatal pesticide exposure and significantly lower IQ at age 7.

A study of 265 New York City minority children has found that those born with higher amounts of the insecticide chlorpyrifos had lower IQ scores at age 7. Those most exposed (top 25%) scored an average 5.3 points lower on the working memory part of the IQ test (WISC-IV), and 2.7 points lower on the full IQ test, compared to those in the lowest quartile.

The children were born prior to the 2001 ban on indoor residential use of the common household pesticide in the US. The babies' umbilical cord blood was used to measure exposure to the insecticide.

Previous research had found that, prior to the ban, chlorpyrifos was detected in all personal and indoor air samples in New York, and 70% of umbilical cord blood collected from babies. The amount of chlorpyrifos in babies' blood was associated with neurodevelopmental problems at age three. The new findings indicate that these problems persist.

While exposure to the organophosphate has measurably declined, agricultural use is still permitted in the U.S.

Similarly, another study, involving 329 7-year-old children in a farming community in California, has found that those with the highest prenatal exposure to the pesticide dialkyl phosphate (DAP) had an average IQ 7 points lower than children whose exposure was in the lowest quintile. Prenatal pesticide exposure was linked to poorer scores for working memory, processing speed, verbal comprehension, and perceptual reasoning, as well as overall IQ.

Prenatal exposure was measured by DAP concentration in the mother’s urine. Urine was also collected from the children at age 6 months and 1, 2, 3½ and 5 years. However, there was no consistent link between children’s postnatal exposure and cognition.

While this was a farming community where pesticide exposure would be expected to be high, the levels were within the range found in the general population.

It’s recommended that people wash fruit and vegetables thoroughly, and limit their use of pesticides at home.

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Proximity to freeway associated with autism

February, 2011

Evidence that environmental toxins might be part of the reason for the increase in autism is supported by a finding that autism risk doubled for those living close to a freeway at birth.

Increased awareness and changes in diagnostic criteria can’t entirely explain the massive increase in autism — the U.S. Centers for Disease Control reported a 57% increase between 2002 and 2006. Another factor may involve environmental pollutants.

A Californian study involving 304 autism cases and 259 typically developing controls has found that living within 309 meters of a freeway at birth or during the third trimester was associated with a two-fold increase in autism risk. This association held after adjustment for gender, ethnicity, parental education, maternal age, or prenatal smoking. The researchers found no consistent pattern of association of autism with proximity to a major road.

The finding is consistent with other evidence that oxidative stress and inflammation are involved in the pathogenesis of autism. This is likely to be only one of many environmental factors that are involved.

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Children with autism lack visual skills required for independence

February, 2011

Autism is popularly associated with intense awareness of systematic regularities, but a new study shows that the skill displayed in computer tasks is not available in real-world tasks.

Contrary to previous laboratory studies showing that children with autism often demonstrate outstanding visual search skills, new research indicates that in real-life situations, children with autism are unable to search effectively for objects. The study, involving 20 autistic children and 20 normally-developing children (aged 8-14), used a novel test room, with buttons on the floor that the children had to press to find a hidden target among multiple illuminated locations. Critically, 80% of these targets appeared on one side of the room.

Although autistics are generally believed to be more systematic, with greater sensitivity to regularities within a system, such behavior was not observed. Compared to other children, those with autism were slower to pick up on the regularities that would help them choose where to search. The slowness was not due to a lack of interest — all the children seemed to enjoy the game, and were keen to find the hidden targets.

The findings suggest that those with ASD have difficulties in applying the rules of probability to larger environments, particularly when they themselves are part of that environment.

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[2055] Pellicano E, Smith AD, Cristino F, Hood BM, Briscoe J, Gilchrist ID. Children with autism are neither systematic nor optimal foragers. Proceedings of the National Academy of Sciences [Internet]. 2011 ;108(1):421 - 426. Available from: http://www.pnas.org/content/108/1/421.abstract

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Twin studies shed light on relationship among ADHD, reading, math

January, 2011

While one twin study points to the common attribute of slow processing speed between those with ADHD and those with reading disabilities, another indicates a role for environment.

A twin study involving 457 pairs has found that ADHD on its own was associated with a reduced ability to inhibit responses to stimuli, while reading disabilities were associated independently with weaknesses on measures of phoneme awareness, verbal reasoning, and working memory. Both disorders were associated with a slow processing speed, and there was a significant genetic correlation between RD and ADHD.

However, just to remind us that genetics are rarely solely the answer, another twin study, involving 271 pairs of 10-year-old identical and fraternal twins, has found evidence that the associations between ADHD symptoms, reading outcomes and math outcomes are a product of both genetic and common environmental influences. The researchers speculate that such environmental influences may include aspects of the classroom and homework environment.

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