Skip to main content
    • Aa
    • Aa
  • Get access
    Check if you have access via personal or institutional login
  • Cited by 31
  • Cited by
    This article has been cited by the following publications. This list is generated based on data provided by CrossRef.

    Broyd, Samantha J. van Hell, Hendrika H. Beale, Camilla Yücel, Murat and Solowij, Nadia 2016. Acute and Chronic Effects of Cannabinoids on Human Cognition—A Systematic Review. Biological Psychiatry, Vol. 79, Issue. 7, p. 557.

    Cadet, Jean Lud and Bisagno, Veronica 2016. Neuropsychological Consequences of Chronic Drug Use: Relevance to Treatment Approaches. Frontiers in Psychiatry, Vol. 6,

    Ganzer, Florian Bröning, Sonja Kraft, Stefanie Sack, Peter-Michael and Thomasius, Rainer 2016. Weighing the Evidence: A Systematic Review on Long-Term Neurocognitive Effects of Cannabis Use in Abstinent Adolescents and Adults. Neuropsychology Review, Vol. 26, Issue. 2, p. 186.

    Jackson, Nicholas J. Isen, Joshua D. Khoddam, Rubin Irons, Daniel Tuvblad, Catherine Iacono, William G. McGue, Matt Raine, Adrian and Baker, Laura A. 2016. Impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies. Proceedings of the National Academy of Sciences, Vol. 113, Issue. 5, p. E500.

    Karschner, Erin L. Swortwood, Madeleine J. Hirvonen, Jussi Goodwin, Robert S. Bosker, Wendy M. Ramaekers, Johannes G. and Huestis, Marilyn A. 2016. Extended plasma cannabinoid excretion in chronic frequent cannabis smokers during sustained abstinence and correlation with psychomotor performance. Drug Testing and Analysis, Vol. 8, Issue. 7, p. 682.

    Yücel, M Lorenzetti, V Suo, C Zalesky, A Fornito, A Takagi, M J Lubman, D I and Solowij, N 2016. Hippocampal harms, protection and recovery following regular cannabis use. Translational Psychiatry, Vol. 6, Issue. 1, p. e710.

    2016. Meyler's Side Effects of Drugs.

    Hooper, Stephen R. Woolley, Donald and De Bellis, Michael D. 2014. Intellectual, neurocognitive, and academic achievement in abstinent adolescents with cannabis use disorder. Psychopharmacology, Vol. 231, Issue. 8, p. 1467.

    Radhakrishnan, Rajiv Addy, Peter H. Sewell, R. Andrew Skosnik, Patrick D. Ranganathan, Mohini and D’Souza, Deepak Cyril 2014. The Effects of Drug Abuse on the Human Nervous System.

    Wilkinson, Samuel T. Radhakrishnan, Rajiv and D’Souza, Deepak Cyril 2014. Impact of Cannabis Use on the Development of Psychotic Disorders. Current Addiction Reports, Vol. 1, Issue. 2, p. 115.

    Faraone, Stephen V. Seidman, Larry J. Buka, Stephen Goldstein, Jill M. Lyons, Michael Kremen, William S. and Glatt, Stephen J. 2013. Festschrift celebrating the career of Ming T. Tsuang. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics, Vol. 162, Issue. 7, p. 551.

    Verdejo-García, Antonio Beatriz Fagundo, Ana Cuenca, Aida Rodriguez, Joan Cuyás, Elisabet Langohr, Klaus de Sola Llopis, Susana Civit, Ester Farré, Magí Peña-Casanova, Jordi and de la Torre, Rafael 2013. COMT val158met and 5-HTTLPR Genetic Polymorphisms Moderate Executive Control in Cannabis Users. Neuropsychopharmacology, Vol. 38, Issue. 8, p. 1598.

    Gonzalez, R. and Swanson, J. M. 2012. Long-term effects of adolescent-onset and persistent use of cannabis. Proceedings of the National Academy of Sciences, Vol. 109, Issue. 40, p. 15970.

    Harding, Ian H Solowij, Nadia Harrison, Ben J Takagi, Michael Lorenzetti, Valentina Lubman, Dan I Seal, Marc L Pantelis, Christos and Yücel, Murat 2012. Functional Connectivity in Brain Networks Underlying Cognitive Control in Chronic Cannabis Users. Neuropsychopharmacology, Vol. 37, Issue. 8, p. 1923.

    Lopez-Larson, Melissa P. Rogowska, Jadwiga Bogorodzki, Piotr Bueler, Charles Elliott McGlade, Erin C. and Yurgelun-Todd, Deborah A. 2012. Cortico-cerebellar abnormalities in adolescents with heavy marijuana use. Psychiatry Research: Neuroimaging, Vol. 202, Issue. 3, p. 224.

    Macher, Rayna B. and Earleywine, Mitchell 2012. Enhancing neuropsychological performance in chronic cannabis users: The role of motivation. Journal of Clinical and Experimental Neuropsychology, Vol. 34, Issue. 4, p. 405.

    Palermo, Liana Bianchini, Filippo Iaria, Giuseppe Tanzilli, Antonio and Guariglia, Cecilia 2012. Assessing Topographical Orientation Skills in Cannabis Users. The Scientific World Journal, Vol. 2012, p. 1.

    Ashtari, Manzar Avants, Brian Cyckowski, Laura Cervellione, Kelly L. Roofeh, David Cook, Philip Gee, James Sevy, Serge and Kumra, Sanjiv 2011. Medial temporal structures and memory functions in adolescents with heavy cannabis use. Journal of Psychiatric Research, Vol. 45, Issue. 8, p. 1055.

    Crean, Rebecca D. Crane, Natania A. and Mason, Barbara J. 2011. An Evidence-Based Review of Acute and Long-Term Effects of Cannabis Use on Executive Cognitive Functions. Journal of Addiction Medicine, Vol. 5, Issue. 1, p. 1.

    Fernández-Serrano, Maria Jose Pérez-García, Miguel and Verdejo-García, Antonio 2011. What are the specific vs. generalized effects of drugs of abuse on neuropsychological performance?. Neuroscience & Biobehavioral Reviews, Vol. 35, Issue. 3, p. 377.


Neuropsychological consequences of regular marijuana use: a twin study

  • M. J. LYONS (a1), J. L. BAR (a1), M. S. PANIZZON (a1), R. TOOMEY (a1), S. EISEN (a1), H. XIAN (a1) and M. T. TSUANG (a1)
  • DOI:
  • Published online: 01 October 2004

Background. Results of previous research examining long-term residual effects of marijuana use on cognition are conflicting. A major methodological limitation of prior studies is the inability to determine whether differences between users and non-users are due to differences in genetic vulnerability preceding drug use or due to the effects of the drug.

Method. Fifty-four monozygotic male twin pairs, discordant for regular marijuana use in which neither twin used any other illicit drug regularly, were recruited from the Vietnam Era Twin Registry. A minimum of 1 year had passed since the marijuana-using twins had last used the drug, and a mean of almost 20 years had passed since the last time marijuana had been used regularly. Twins were administered a comprehensive neuropsychological test battery to assess general intelligence, executive functioning, attention, memory and motor skills. Differences in performance between marijuana-using twins and their non-using co-twins were compared using a multivariate analysis of specific cognitive domains and univariate analyses of individual test scores. Dose–response relationships were explored within the marijuana-using group.

Results. Marijuana-using twins significantly differed from their non-using co-twins on the general intelligence domain; however, within that domain only the performance of the block design subtest of the Wechsler Adult Intelligence Scale – Revised reached a level of statistical significance.

Conclusions. Out of the numerous measures that were administered, only one significant difference was noted between marijuana-using twins and their non-using co-twins on cognitive functioning. The results indicate an absence of marked long-term residual effects of marijuana use on cognitive abilities.

Corresponding author
Dr Michael J. Lyons, Psychology Department, Boston University, 64 Cummington Street, Boston, MA 02215, USA. (Email:
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Psychological Medicine
  • ISSN: 0033-2917
  • EISSN: 1469-8978
  • URL: /core/journals/psychological-medicine
Please enter your name
Please enter a valid email address
Who would you like to send this to? *