<http://schema.org/description>
"(Medical Xpress) -- As we get older, our cognitive abilities change, improving when we&amp;amp;#146;re younger and declining as we age. Scientists posit a hierarchical structure within which these abilities are organized. There&amp;amp;#146;s the &amp;amp;#147;lowest&amp;amp;#148; level&amp;amp;#151; measured by specific tests, such as story memory or word memory; the second level, which groups various skills involved in a category of cognitive ability, such as memory, perceptual speed, or reasoning; and finally, the &amp;amp;#147;general,&amp;amp;#148; or G, factor, a sort of statistical aggregate of all the thinking abilities."^^<http://www.w3.org/2001/XMLSchema#string>
<http://medicalxpress.com/news/2011-11-nature-aging-brains.html>