A team of scientists, led by psychiatric geneticists at Washington University School of Medicine in St. Louis, has gathered the most extensive evidence to date that a gene that activates signaling pathways in the brain influences one kind of intelligence. They have confirmed a link between the gene, CHRM2, and performance IQ, which involves a person's ability to organize things logically.
"This is not a gene FOR intelligence," says Danielle M. Dick, Ph.D., assistant professor of psychiatry and lead author on the study. "It's a gene that's involved in some kinds of brain processing, and specific alterations in the gene appear to influence IQ. But this single gene isn't going to be the difference between whether a person is a genius or has below-average intelligence."
Dick's team comprehensively studied the DNA along the gene and found that several variations within the CHRM2 gene could be correlated with slight differences in performance IQ scores, which measure a person's visual-motor coordination, logical and sequential reasoning, spatial perception and abstract problem solving skills. When people had more than one positive variation in the gene, the improvements in performance IQ were cumulative. The study's findings are available online in Behavioral Genetics and will appear in an upcoming print issue of that journal.
IQ tests also measure verbal skills and typically include many subtests. For this study, subjects took five verbal subtests and four performance subtests, but the genetic variations influenced only performance IQ scores.
"One way to measure performance IQ may be to ask people to order pictures correctly to tell a story," Dick explains. "A simple example might be pictures of a child holding a vase, the vase broken to bits on the floor and the child crying. The person taking the test would have to put those pictures int
Source:Washington University School of Medicine