According to a study published online in the Journal of Epidemiology and Community Health, a high IQ in childhood could be associated to illegal drug use later in life, especially among women. The researchers findings were based on data from just under 8,000 individuals in the 1970 British Cohort Study, a large ongoing population based investigation, which examines educational attainment, lifetime drug use as well as socioeconomic factors.

Researchers used a validated scale in order to measure the IQ scores of participants at the ages of 5 and ten years. In addition they collected information on participants self reported levels of drug use and psychological distress at the age of 16 and again at the age of 30 (drug use only).

Drug use included cocaine, cannabis, LSD (acid), heroin, downers (tanks, blues, barbiturates), and uppers (speed and wiz).

They discovered that 1 in 3 men (35.4%) and 1 in 6 women (15.9%) had used cannabis by the age of 30. Furthermore, they found that in the previous 12 months 3.6% of women and 8.6% of men had used cocaine.

For other drugs they discovered a similar pattern of use, with overall drug use two times as prevalent in men as among women participants.

When intelligence was taken into account, the examination revealed that men who received high IQ scores when they were 5 years old were approximately 50% more likely to have taken ecstasy, several illegal drugs, and amphetamines 25 years later compared to men who received low IQ scores.

Women with a high IQ score were more than two times as likely to have used cocaine and cannabis later in life compared to those with low IQ scores.

They discovered that the same associations appeared between participants who received a high IQ score at the age of 10 and subsequent use of ecstasy, cannabis, multiple drug use and cocaine, even though this last connection was only apparent at age 30.

The discoveries held true, regardless of parental social class, lifetime household income and anxiety/depression during adolescence.

The researchers explain:

“Although most studies have suggested that higher child or adolescent IQ prompts the adoption of a healthy lifestyle as an adult, other studies have linked higher childhood IQ scores to excess alcohol intake and alcohol dependency in adulthood.”

Even though it is not exactly clear why there should be an association between illegal drug use and high IQ, the researchers highlight that prior investigations have revealed that individuals who are highly intelligent are open to experiences and keen on stimulation and novelty.

In addition other studies have shown that children who are intelligent are usually easily bored and suffer at the hands of their peers for being different, “either of which could conceivably increase vulnerability to using drugs as an avoidant coping strategy,” say the researchers.

Written by Grace Rattue