People With Higher IQ’s Are More Likely to Use Illegal Drugs… Why?

Researchers have found that those with high childhood IQs are more prone to illegal drug use as adults. But what does this correlation really mean?

Intelligent-People-Are-More-Likely-to-Use-Drugs

Two major papers have found a positive correlation between high childhood IQ and adult drug use.

The first was published in 2011 (Intelligence across childhood in relation to illegal drug use in adulthood: 1970 British Cohort Study). The second was published in 2012 (Intelligence quotient in childhood and the risk of illegal drug use in middle-age: the 1958 National Child Development Survey). Both were co-authored by James W. White PhD and all of the data for both research papers comes from The Centre for Longitudinal Studies (CLS), a research council operating from the Department for Quantitative Social Science, Institute of Education, at the University of London.

Perhaps it is the concept of intelligence that needs to be reconsidered in order to answer the question; IQ does not measure emotional intelligence or creativity.

Longitudinal studies observe variables over extended periods of time. Cohort studies are longitudinal studies of groups of people with shared characteristics or experiences; for example, the 1958 study follows the lives of 17,000 people born within the United Kingdom in a single week in 1958. The cohort is that group of 17,000 people. The CLS has done several such studies: in 1958, in 1970, another in 1989, and the Millennium Cohort Study of 2000-2001. All of these studies are, by definition, ongoing.

The CLS has provided data for publications on the most disparate topics: from the visual acuity of a national sample (Developmental Medicine and Child Neurology) to The Role of Breakfast Cereals in the Diets of 16-17-year-old Teenagers in Britain (Journal of Human Nutrition and Dietetics). Thus far, only the two aforementioned papers investigate a direct link between drug use and intelligence.

See also: 10 famous geniuses and their drugs of choice

The 1958 cohort consists of 3,509 males and 3,204 females. All of the participants underwent cognitive ability testing at age 11. The test consisted of 40 verbal and 40 nonverbal items, created by The National Foundation for Educational Research in England and Wales, and was tried against other testing methods for validity. Cognitive ability scores were then “transformed into IQ equivalents to give a cohort mean of 100 and standard deviation of 15.” At the age of 42, participants were asked to complete a drug questionnaire. The questionnaire inquired about the use of cannabis, cocaine, amphetamines, ecstasy, LSD, amyl nitrate, psilocybin mushrooms, temazepam, ketamine, crack, heroin, methadone, and the fictitious drug semeron to identify false claims. Adjustments were made for socioeconomic background, material disadvantage, and antisocial behavior, though the study claims that “associations between IQ and most drugs were materially unchanged after these adjustments.” For men and women, one standard deviation increase in IQ scores (15 points) was associated with an increased risk of using all drugs with the exception of cocaine, amphetamines, ecstasy, and temazepam in men; ecstasy and temazepam in women.

While the strengths of this study are the size of the sample and the length of participant contact, there is limited data on the actual patterns of drug use. The 1958 cohort study lists a number of other studies which claim a correlation between IQ and generally good health practices such as lower rates of smoking, greater levels of physical activity, and increased intake of fruits and vegetables, which makes the link between IQ and drug use very curious: “These findings suggest that, in contrast to most studies on the association between childhood IQ and later health, a high childhood IQ may prompt the adoption of behaviors that are potentially harmful to health (ie, excess alcohol consumption and drug use) in adulthood” (1958 Cohort Study).

The 1970 cohort study differs slightly from the 1958 study in methodology. The 1970 study is the largest to date to examine childhood IQ and drug use, with 3,818 male participants and 4,128 female. At the age of five, researchers went to the participants’ homes and administered four tests of cognitive function: the Human Figure Drawing Test, a Copying Designs Test, the English Picture Vocabulary Test and the Profile Test. Scores were calculated and transformed into the IQ distribution (mean=100, SD=15). Intelligence was assessed a second time, at the age of ten, using a modified version of the British Ability Scales, and transformed into the commonly used IQ distribution.

At 16, participants reported on their level of psychological distress using a 12-item General Health Questionnaire, as well as their drug use, by way of simple yes or no questions. For example, “Have you ever tried taking cannabis?” The drugs on the questionnaire, street names included, were cannabis, cocaine, uppers, downers, LSD, heroin, and the fictitious semeron.

At the age of 30, participants were tested again on psychological distress and drug use. They also answered questions on educational achievement, salary, occupation, and social class. As in the 1958 cohort study, adjustments were made to account for psychological distress and socioeconomic background. It was discovered at the ages of 16 and 30 that both male and female participants who reported using illicit drugs had significantly higher childhood IQ scores.

Men who had used cannabis by age 16 had a mean IQ score of 109.65, men who had not had a mean IQ of 103.86. Men at 30 who had used multiple drugs within the previous 12 months had a mean IQ score of 104.72, men who had not had a mean IQ score of 101.69.

See also: Top dangerous drugs in the world

Women consistently showed greater correlation between IQ score and drug use. Women who had tried cannabis by age 16 had a mean IQ score of 107.74, women who had not had a mean IQ score of 101.42. Women at 30 who had used multiple drugs within the previous 12 months had a mean IQ score of 108.85, women who had not had a mean IQ score of 100.31.

The study suggests that greater intelligence is associated with novelty seeking, “A possible pathway that emerges from the literature on personality is that high IQ individuals have also been shown to score highly on tests of stimulation seeking and openness to experience.”

Though no specific studies are cited linking intelligence and stimulation, it isn’t difficult to find literature that supports these claims. Stimulation Seeking and Intelligence: A Prospective Longitudinal Study published in the Journal of Personality and Social Psychology in 2002, asserts that it is the first study to show a link between between stimulation seeking and intelligence, hypothesizing that stimulation seekers are looking to create an enriched environment for their cognitive development.

If it is true that higher intelligence correlates with stimulation seeking behaviors, the question that follows is why. Some evolutionary psychologists attempt to explain the motivation behind the desire to grow intelligence through stimulation and novelty, claiming that it was an evolutionary imperative to be able to solve new problems, and thus people with greater intelligence are drawn to the novel. One evolutionary psychologist has made a name for himself online making such claims.

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