Format

Send to

Choose Destination
Drug Alcohol Depend. 2019 Nov 2:107712. doi: 10.1016/j.drugalcdep.2019.107712. [Epub ahead of print]

Investigating the causal effect of cannabis use on cognitive function with a quasi-experimental co-twin design.

Author information

1
Institute for Behavioral Genetics, University of Colorado Boulder, 447 UCB, Boulder, CO, 80309, United States. Electronic address: Jessica.M.Ross@Colorado.edu.
2
Department of Psychology and Neuroscience, University of Colorado Boulder, United States; Department of Psychiatry, University of Colorado School of Medicine, United States.
3
Institute for Behavioral Genetics, University of Colorado Boulder, 447 UCB, Boulder, CO, 80309, United States; Department of Psychology and Neuroscience, University of Colorado Boulder, United States.
4
Institute for Behavioral Genetics, University of Colorado Boulder, 447 UCB, Boulder, CO, 80309, United States.

Abstract

BACKGROUND:

It is unclear whether cannabis use causes cognitive decline; several studies show an association between cannabis use and cognitive decline, but quasi-experimental twin studies have found little support for a causal effect. Here, we evaluate the association of cannabis use with general cognitive ability and executive functions (EFs) while controlling for genetic and shared environmental confounds in a longitudinal twin study.

METHODS:

We first examined the phenotypic associations between cannabis initiation, frequency, and use disorder with cognitive abilities, while also controlling for pre-use general cognitive ability and other substance involvement. We tested the concurrent association between the cannabis use variables and cognitive abilities in late adolescence and young adulthood and the longitudinal association between cannabis use variables during adolescence and young adulthood cognitive abilities. Next, we used multilevel models to test whether these relations reflect between- and/or within-twin pair associations.

RESULTS:

Phenotypically, cannabis use was related to poorer cognitive functioning, although most associations were negligible after accounting for other substance use. Nevertheless, there were few significant within-family twin-specific associations, except that age 17 cannabis frequency was associated with worse age 23 Common EF and general cognitive ability.

CONCLUSIONS:

We found little support for a potential causal effect of cannabis use on cognition, consistent with previous twin studies. Results suggest that cannabis use may not cause decline in cognitive ability among a normative sample of cannabis users.

KEYWORDS:

Adolescence; Cannabis; Executive control; Intelligence; Young adulthood

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center