Elsevier

Addictive Behaviors

Volume 35, Issue 2, February 2010, Pages 172-174
Addictive Behaviors

Short Communication
Heritability of cannabis initiation in Dutch adult twins

https://doi.org/10.1016/j.addbeh.2009.09.015Get rights and content

Abstract

Previous studies exploring the heritability of cannabis initiation have been carried out in the United States, Australia and United Kingdom. In the present study we assess cannabis initiation in The Netherlands, where the use of cannabis in small amounts is permitted. The sample included 3115 twins with a mean age of 27.4 years (SD 4.7) who are registered with the Netherlands Twin Register (NTR). Individual differences in cannabis initiation showed moderate genetic influences (44%). The remaining variance was explained by environmental influences shared by twins (31%) and by unique environmental factors (24%). Compared to studies from other countries, these results suggest that the relative importance of genetic and environmental factors is not different in a country with a more liberal cannabis policy.

Introduction

Cannabis is a commonly used drug worldwide. An estimated 166 million people used cannabis in 2006/7, equivalent to about 4 percent of the global population aged 15-64 (World Drug Report 2008).

Cannabis use is associated with increased risk for the subsequent use of more harmful drugs such as cocaine and heroin (Lynskey, Vink, & Boomsma, 2006) and higher risk to psychotic symptoms (Chen & Lin, 2009). Therefore it is important to know what causes people to initiate cannabis use. Twin studies can be used to disentangle the magnitude of genetic and environmental influences. Previous studies have reported both genetic and environmental factors as significant contributors to cannabis initiation. The heritability estimates ranged from 13% to 72%, while the shared environmental influences ranged from 0% to 68% (Kendler et al., 2000, Lynskey et al., 2002, Maes et al., 1999, McGue et al., 2000, Miles et al., 2001, Rhee et al., 2003, Shelton et al., 2007). These studies were mainly done in the United States, Australia and United Kingdom. In contrast to those countries, the use of cannabis in small amounts is, although not legal, permitted in the Netherlands. In the present study we use data from a sample of Dutch twins to examine the heritability of cannabis initiation in a country with a liberal cannabis policy.

Section snippets

Sample

Subjects are registered with the Netherlands Twin Register (NTR) (Boomsma et al., 2006). Most of them participate in longitudinal studies of health, lifestyle and personality. For this study we focused on the data from the 2000 survey (Vink and Boomsma, 2008, Vink et al., 2007), which was completed by 4609 twins. We selected participants between 21 and 40 years (N = 3115). Mean age of the subjects was 27.4 years old (SD = 4.7). Zygosity was based on DNA tests or on questions concerning similarity.

Cannabis initiation

The

Results

The prevalence in cannabis initiation did not differ for MZ or DZ twins (Table 1, model 1b), indicating that there is no process of social interaction between the co-twins. Constraining the thresholds to be the same in men and women resulted in a significant worsening of the model fit (Table 1, model 1c). The prevalence of cannabis initiation in men was 36.2% compared to 24.7% in women. The tetrachoric correlations derived from the best fitting model (model 1b), which allowed for different

Discussion

The prevalence of cannabis initiation was significantly higher in men than in women, which is in line with other studies (Degenhardt et al., 2008). The heritability estimates for cannabis initiation were the same in both sexes. The size of the estimate (44%) seems in line with other studies exploring the heritability of cannabis initiation. However, it should be noted that the heritability estimates in other studies ranged from 13% to 72%. This could be due to several factors, like phenotypic

Web resources

World Drug Report: http://www.unodc.org/unodc/en/data-and-analysis/WDR-2008.html

Netherlands Twin Register: www.tweelingenregister.org

Role of funding sources

This study was funded by NWO grant 985-10-002, by ZonMW (Addiction) grant 31160008 and by NIH DA018673 (Psychometric and genetic assessments of substance use, PI Neale). Dr. Vink is financially supported by NWO (VENI 451-06-004). These organizations had no further role in study design, in the collection, analysis and interpretation of data, in the writing of the report, or in the decision to submit the paper for publication.

Contributors

L.W. carried out preliminary analysis and a literature search. J.V. undertook the final analyses and wrote the manuscript. D.B. and M.N. helped in the design and implementation of the study and in the interpretation of the results. All authors contributed to and have approved the final manuscript.

Conflict of interest

All authors declare that they have no conflicts of interest.

References (16)

  • D.R. Miles et al.

    A twin study on sensation seeking, risk taking behavior and marijuana use

    Drug and Alcohol Dependence

    (2001)
  • D.I. Boomsma et al.

    Netherlands Twin Register: from twins to twin families

    Twin Research and Human Genetics

    (2006)
  • G. Carey

    Sibling imitation and contrast effects

    Behavior Genetics

    (1986)
  • C.Y. Chen et al.

    Health consequences of illegal drug use.Chen CY, Lin KM

    Current Opinion in Psychiatry

    (2009)
  • L. Degenhardt et al.

    Toward a global view of alcohol, tobacco, cannabis, and cocaine use: findings from the WHO World Mental Health Surveys

    PLoS Med

    (2008)
  • D.S. Falconer et al.

    Treshold Characters (chapter 18)

    Quantitative Genetics

    (1996)
  • K.S. Kendler et al.

    Illicit psychoactive substance use, heavy use, abuse and dependence in a US population-based sample of male twins

    Archives of General Psychiatry

    (2000)
  • M.T. Lynskey et al.

    Genetic and environmental contributions to cannabis dependence in a national young adult twin sample

    Psychological Medicine

    (2002)
There are more references available in the full text version of this article.

Cited by (14)

  • Investigating the genetic and causal relationship between initiation or use of alcohol, caffeine, cannabis and nicotine

    2020, Drug and Alcohol Dependence
    Citation Excerpt :

    Genetic influences play an important role in the use of multiple substances. Twin studies reported a wide range of heritability estimates of substance use phenotypes: 0.39−0.51 for coffee consumption (Luciano et al., 2005; Vink et al., 2009), 0.44−0.48 for the initiation of cannabis use (Verweij et al., 2010; Vink et al., 2010), - 0.75−0.44 for the initiation of smoking (Chang et al., 2018; Maes et al., 2004; Vink et al., 2005), and 0.24−0.53 for a range of alcohol consumption and alcohol use disorder phenotypes (Chang et al., 2018; Grant et al., 2009; Sartor et al., 2009; van Beek et al., 2012). Recent genetic association studies based on the variation in single nucleotide polymorphisms (SNPs) provide the support that the genes underlying use of one substance are overlapping with those underlying use of other substances.

  • Early adolescent patterns of alcohol, cigarettes, and marijuana polysubstance use and young adult substance use outcomes in a nationally representative sample

    2014, Drug and Alcohol Dependence
    Citation Excerpt :

    This latter notion is also consistent with Problem Behavior theory, which posits that some individuals possess a personality proneness, environmental proneness, and behavioral proneness to engage in multiple problem behaviors (such as delinquency, substance abuse, or criminality) that depart from social and legal norms and can result in mild social reproof, social rejection, or even incarceration (Jessor, 1987; Jessor et al., 2006). It is noteworthy that although Problem Behavior Theory tends to emphasize psychosocial factors leading to “proneness,” there is a burgeoning body of genetic evidence for both specific patterns of drug-associated risks (Agrawal and Lynskey, 2006; Batra et al., 2003; Distel et al., 2011; Ehlers et al., 2010; Gillespie et al., 2007; Horimoto et al., 2012; Li, 2003; Pickens et al., 1991; Vink et al., 2010; Wang et al., 2012), and an emerging literature reporting significant heritability for the common addiction liability diathesis (Hicks et al., 2012; Palmer et al., 2012; Vanyukov and Ridenour, 2012; Vrieze et al., 2012a,b). In this study, we use data from a nationally representative survey to examine the U.S. prevalence of various patterns of early adolescent (prior to age 16) use of alcohol, cigarettes, and marijuana individually and in combination and differences of these patterns in age, gender, and race/ethnicity among users of all three substances.

View all citing articles on Scopus
View full text