Research using data from a population-based birth cohort from Rotterdam, in The Netherlands, has found that children exposed to higher levels of air pollution when they were in womb had significantly thinner cortex in several brain regions. Some of this appeared to be related to impaired inhibitory control.
More than 10% of all babies are born preterm every year, and prematurity is a well-established risk factor for cognitive impairment at some level.
In a recent German study involving 1326 8-year-old children, it was found that being born preterm specifically affected the ability to solve tasks with a high cognitive load (i.e. greater demands on working memory), whereas tasks with a low load were largely unaffected.
It’s always difficult in human studies to disentangle the effects of lifestyle factors. Alcohol is a case in point, and in particular the vexed question of whether any alcohol is safe during pregnancy. A new study, however, has avoided the complication of co-occurring lifestyle and environment factors by looking directly at genetic variants.
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An exam, called the NICU (neonatal intensive care unit) Network Neurobehavioral Scale (NNNS), has been created to identify newborns who may have problems with school readiness and behavior at age four. This opens up the possibility of early intervention to prevent these problems. The screening exam has been tested on 1248 babies, mostly black and on public assistance. Five discrete behavioral profiles were reliably identified; the most extreme negative profile was found in 5.8% of the infants. Infants with poor performance were more likely to have behavior problems at age three, school readiness problems at age four, and low IQ at 4 ½ — 40% had clinically significant problems externalizing (impulsivity and acting out), internalizing (anxiety, depression, withdrawn personalities), and with school readiness (delays in motor, concepts and language skills), and 35% had low IQ.
Liu, J., Bann, C., Lester, B., Tronick, E., Das, A., Lagasse, L., … Bada, H. (2010). Neonatal neurobehavior predicts medical and behavioral outcome. Pediatrics, 125(1), e90-98 . Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/19969621
http://www.eurekalert.org/pub_releases/2009-12/bu-nst120709.php
Down syndrome is characterized by specific learning impairments (for example, difficulties in using spatial and contextual information to form new memories, but less difficulty at remembering information linked to sensory cues) that point to the hippocampus as a problem area. Investigation has revealed that the problem lies in degeneration of the locus coeruleus, which sends norepinephrine to neurons in the hippocampus. Now a study using genetically engineered mice has found that norepinephrine precursor drugs improved performance in the mice within a few hours. However, the effect did wear off quite quickly too. Other research has looked at acetylcholine, which also acts at the hippocampus. The present findings suggest the best medication regimen will be one that improves both norepinephrine and acetylcholine signals. Locus coeruleus degeneration is also seen in dementia; Alzheimer’s develops among those with Down syndrome at a significantly higher rate than in the general population.
Salehi, A. et al. 2009. Restoration of Norepinephrine-Modulated Contextual Memory in a Mouse Model of Down Syndrome. Science Translational Medicine, 1 (7), 7-17.
http://www.eurekalert.org/pub_releases/2009-11/sumc-nds111309.php
http://www.eurekalert.org/pub_releases/2009-11/uoc--cdr111609.php http://www.the-scientist.com/blog/display/56154/
A study demonstrating the perils of one-time testing gave 16 common cognitive and neuropsychological tests to groups of people ages 18-39, 50-59 and 60-97 years. The variation between scores on the same test given three times during a two-week period was as big as the variation between the scores of people in different age groups. “It's as if on the same test, someone acted like a 20-year-old on a Monday, a 45-year-old on Friday, and a 32-year-old the following Wednesday”. The study makes clear the dangers of diagnosing learning disability, progressive brain disease or impairment from head injury on the basis of testing on a single occasion. The researcher suggests we should view cognitive abilities as a distribution of many potential levels of performance instead of as one stable short-term level; that people have a range of typical performances, a one-person bell curve. It may also be that within-person variability could be a useful diagnostic marker in itself — for example, extreme fluctuations might be an early warning of mental decline.
Salthouse, T. A. (2007). Implications of within-person variability in cognitive and neuropsychological functioning for the interpretation of change. Neuropsychology, 21(4), 401-411. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/17605573
http://www.physorg.com/news102689828.html
http://www.eurekalert.org/pub_releases/2007-07/apa-csv062507.php
Following their discovery that neurofibromatosis 1 (NF1) — the leading genetic cause of learning disabilities — is linked to dysfunction in a protein called Ras, researchers have successfully used a commonly prescribed cholesterol-lowering statin drug (lovastatin) to reverse the learning deficits in mice. Clinical trials with humans are being planned.
Li, W., Cui, Y., Kushner, S., Brown, R., Jentsch, J., Frankland, P., … Silva, A. (2005). The HMG-CoA Reductase Inhibitor Lovastatin Reverses the Learning and Attention Deficits in a Mouse Model of Neurofibromatosis Type 1. Current Biology, 15(21), 1961-1967. Retrieved from http://www.cell.com/current-biology/abstract/S0960-9822(05)01113-9
http://www.eurekalert.org/pub_releases/2005-11/uoc--rf110405.php
http://www.newscientist.com/channel/health/dn8276
Chromosome 22q11.2 deletion syndrome is the most common genetic deletion syndrome, and causes symptoms such as heart defects, cleft palate, abnormal immune responses and cognitive impairments. Two related studies have recently cast more light on these cognitive impairments. Previously it was known that numerical abilities were impaired more than verbal skills. The new study found children with the chromosome deletion performed more poorly on experiments designed to test visual attention orienting, enumerating, and judging numerical magnitudes. All three tasks relate to how the children mentally represent objects and the spatial relationships among them, supporting previous arguments that such visual-spatial skills are a fundamental foundation to the later learning of counting and mathematics. The second study found that such children had changes in the shape, size and position of the corpus callosum, the main bridge between the two hemispheres.
Simon, T. J., Bearden, C. E., Mc-Ginn, D. M., & Zackai, E. (2005). Visuospatial and Numerical Cognitive Deficits in Children with Chromosome 22Q11.2 Deletion Syndrome. Cortex, 41(2), 145-155. Retrieved from http://www.sciencedirect.com/science/article/B8JH1-4S0JBRK-7/2/ad6567fc8ae7be0ddb6387920387fc1a
Simon, T. J., Ding, L., Bish, J. P., McDonald-McGinn, D. M., Zackai, E. H., & Gee, J. (2005). Volumetric, connective, and morphologic changes in the brains of children with chromosome 22q11.2 deletion syndrome: an integrative study. NeuroImage, 25(1), 169-180. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/15734353
http://www.eurekalert.org/pub_releases/2005-03/chop-lbt030205.php
An Australian study of 3796 14-year-olds has found that those who had been reported as having suffered abuse or neglect (7.9%) scored the equivalent of some three IQ points lower than those who had not been maltreated, after accounting for a large range of socioeconomic and other factors. Abuse and neglect were independent factors: those who suffered both (and 74% of those who suffered neglect also suffered abuse) were doubly affected.
Last year I reported on a study involving 210 subjects aged 7 to 31 that found that in contrast to the adult brain, most of the tightest connections in a child's brain are between brain regions that are physically close to each other. As the child grows to adulthood, the brain switches from an organization based on local networks based on physical proximity to long-distance networks based on functionality. Now the same researchers, using five-minute scans from 238 people aged 7 to 30, have looked at nearly 13,000 functional (rather than structural) connections and identified 200 key ones.
Neurofibromatosis type 1 (NF1) is the most common cause of learning disabilities, caused by a mutation in a gene that makes a protein called neurofibromin. Mouse research has now revealed that these mutations are associated with higher levels of the inhibitory neurotransmitter GABA in the medial prefrontal cortex. Brain imaging in humans with NF1 similarly showed reduced activity in the prefrontal cortex when performing a working memory task, with the levels of activity correlating with task performance.
A new automated vocal analysis technology can discriminate pre-verbal vocalizations of very young children with autism with 86% accuracy. The LENA™ (Language Environment Analysis) system also differentiated typically developing children and children with autism from children with language delay. The processor fits into the pocket of specially designed children's clothing and records everything the child vocalizes.