Researchers have revealed that they have successfully identified a gene that affects memory and IQ among students.
Chun-Yen Chang, an education researcher at National Taiwan Normal University in Taipei, says that teens with a particular mutation in the COMT gene have been found to score significantly lower on a national placement exam, compared with students who had other versions of the gene.
Each year, a high-stakes exam in Taiwan determines which of the students taking it will go to a prestigious public senior high school or more middling private and vocational schools.
About 310,000 16- and 17-year-olds sit the exam every year.
Chang highlights the fact that pupils are under extreme pressure to perform well in the test, and many employ tutors and practise for years leading up to the exam.
As part of the current study, Chang's team compared the scores of 779 students - 314 boys and 465 girls - from four schools with each student's COMT genotype.
The researcher says that COMT makes an enzyme that recycles a neurotransmitter called dopamine, and that its different versions have been linked to differences in cognitive function.
Chang points out that people with two copies of the Met-158 mutation tend to have a better working memory and higher verbal IQs than those with one or two copies of the Val-158 mutation.
Thus, it appeared probable that pupils having two copies of Met-158 would be more likely to ace the test, said the researcher.
However, that's not what happened.
"When we first got this result we were surprised," New Scientist quoted Chang as saying.
The researcher revealed that the 60 students with two copies of the Met-158 mutation scored far worse than other students, particularly those with two copies of Val-158, on the physical science and social science portions of the exam.
Their scores in mathematics, English, Chinese and writing also tended to be lower than those of other students.
Chang says that the Met-158 mutation not only affect memory and verbal IQ, but it has also been linked to mental illness, anxiety and emotional vulnerability in previous research.
Based on that observation, Chang suggests that in the context of an extremely stressful, high-stakes exam, it makes sense that students with the Met-158 allele tested more poorly than others.
Chang, however, is not sure whether or not his team's findings will apply to other groups.
He speculates that the results may be specific to Asian countries like Taiwan, South Korea and Japan, where national exams can make or break a student's future.
A research article on his study has been published in the journal Brain and Cognition.