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High IQ girls ’twice as likely’ to take drugs in their 30s

15 November 2011

Girls with high childhood IQs are more likely to take illegal drugs in their 30s, new research has uncovered.

Dr James White from Cardiff University’s Centre for the Development and Evaluation of Complex Interventions for Public Health Improvement (DECIPHer) examined data from just under 8000 people in the 1970 British Cohort Study, a large ongoing population based study, which looks at lifetime drug use, socioeconomic factors, and educational attainment.

The IQ scores of the participants were measured at the ages of 5 and 10 years, using validated scales, and information was gathered on self reported levels of psychological distress and drug use at the age of 16, and again at the age of 30.

Drugs assessed at 16 included cannabis and cocaine; and at 30 years of age included cannabis; cocaine; amphetamines; and ecstasy.

By the age of 30, around one in three men (35.4%) and one in six women (15.9%) had used cannabis, while 8.6% of men and 3.6% of women had used cocaine, in the previous 12 months. A similar pattern of use was found for the other drugs, with overall drug use twice as common among men as among women.

Men with high IQ scores at the age of 5 were around 50% more likely to have used amphetamines, ecstasy, and several illicit drugs than those with low scores, 25 years later.

The link was even stronger among women, who were more than twice as likely to have used cannabis and cocaine as those with low IQ scores. The same associations emerged between a high IQ score at the age of 10 and subsequent use of cannabis, ecstasy, amphetamines, and cocaine, although this last was only evident at the age of 30.

Dr White, who led the research, said: "Although most studies suggest 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.

"Although it is not yet clear exactly why there should be a link between high IQ and illicit drug use, previous research has shown that people with a high IQ are more open to new experiences and keen on novelty and stimulation".

"There is a clear need for future epidemiological and experimental studies to explore these and other pathways."

Recognised risk factors for drug use, such as, levels of anxiety/depression during adolescence, parental social class, level of education, social class at 30 years and monthly income were all taken into account during analysis of the study’s findings.

Notes to Editor

Intelligence across childhood in relation to illegal drug use in adulthood: 1970 British Cohort Study Online First doi: 10.1136/jech-2011-200252 was published in the Journal of Epidemiology and Community Health: A copy of the paper is available, on request.


The Centre for the Development and Evaluation of Complex Interventions for Public Health Improvement (DECIPHer; is one of five UKCRC Public Health Research Centres of Excellence. DECIPHer brings together leading experts from a range of disciplines tackling public health issues such as diet and nutrition, physical activity; and alcohol, tobacco and drugs, with a particular focus on developing and evaluating multi-level interventions that have an impact on the health and well-being of children and young people.

The Centre engages strongly with policy, practice and public user communities to translate the research results into practical outcomes. DECIPHer is part of a £20 million investment into public health research and is funded by the UK Clinical Research Collaboration (UKCRC) comprising the Economic & Social Research Council, The British Heart Foundation, Cancer Research UK, the Wellcome Trust, the Welsh Government and the Medical Research Council.

Cardiff University

Cardiff University is recognised in independent government assessments as one of Britain’s leading teaching and research universities and is a member of the Russell Group of the UK’s most research intensive universities. Among its academic staff are two Nobel Laureates, including the winner of the 2007 Nobel Prize for Medicine, University President Professor Sir Martin Evans.

Founded by Royal Charter in 1883, today the University combines impressive modern facilities and a dynamic approach to teaching and research. The University’s breadth of expertise in research and research-led teaching encompasses: the humanities; the natural, physical, health, life and social sciences; engineering and technology; preparation for a wide range of professions; and a longstanding commitment to lifelong learning. Three major new Research Institutes, offering radical new approaches to neurosciences and mental health, cancer stem cells and sustainable places were announced by the University in 2010.

Further information/media interview:

Dr James White

The Centre for the Development and Evaluation of Complex Interventions for Public Health Improvement (DECIPHer)

School of Medicine

Cardiff University
Tel: 029 20687243



Chris Jones

Public Relations

Cardiff University

Tel: 029 20 874731