Down syndrome

Older news items (pre-2010) brought over from the old website

New screening tool helps identify children at risk

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40% had clinically significant problems externalizing (impulsivity and acting out), internalizing (anxiety, depression, withdrawn personalities), and with school readiness (delays in motor, concepts and language skills), and 35% had low IQ.

http://www.eurekalert.org/pub_releases/2009-12/bu-nst120709.php

Cognitive dysfunction reversed in mouse model of Down syndrome

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/

Testing one time is not enough

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.

http://www.physorg.com/news102689828.html
http://www.eurekalert.org/pub_releases/2007-07/apa-csv062507.php

Common cholesterol-lowering drug reverses learning disabilities in mice

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.

http://www.eurekalert.org/pub_releases/2005-11/uoc--rf110405.php
http://www.newscientist.com/channel/health/dn8276

More light on a common developmental disorder

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.

http://www.eurekalert.org/pub_releases/2005-03/chop-lbt030205.php