The data come from the 1970 British Cohort Study, which has been following thousands of people over a period of decades, reports Jennifer Bixler at CNN. The children’s IQ scores were taken at ages 5, 10 and 16. The study also asked about drug use, among other questions.
When the participants turned 30, they were asked if they had used drugs such as marijuana, cocaine and heroin in the past year.
The study found that men with high childhood IQs were up to twice as likely to use illegal drugs as adults than their lower-IQ former classmates. The difference was even more pronounced in girls, where those with high IQs were up to three times more likely to use drugs as adults.
A high IQ is defined as a score between 107 and 158, with an average IQ being 100.
The findings don’t come as a shock to the lead researcher.
“Previous research found for the most part people with high IQs lead a healthy life, but that they are more likely to drink to excess as adults,” said James White, a psychologist at Cardiff University in the United Kingdom.
“We suspect they may be more open to new experiences and are more sensation seeking,” White said. Other factors, according to the paper, which was published in the Journal of Epidemiology and Community Health, are that high IQ kids may use drugs due to boredom or in an attempt to cope with being different.