Psychopharmacology

, Volume 210, Issue 3, pp 429–438

Effects of marijuana on visuospatial working memory: an fMRI study in young adults

  • Andra M. Smith
  • Carmelinda A. Longo
  • Peter A. Fried
  • Matthew J. Hogan
  • Ian Cameron
Original Investigation

DOI: 10.1007/s00213-010-1841-8

Cite this article as:
Smith, A.M., Longo, C.A., Fried, P.A. et al. Psychopharmacology (2010) 210: 429. doi:10.1007/s00213-010-1841-8

Abstract

Objectives

The effects of marijuana use on visuospatial working memory were investigated in 19–21-year-olds using functional magnetic resonance imaging (fMRI).

Methods

Participants were members of the Ottawa Prenatal Prospective Study, a longitudinal study that collected a unique body of information on participants from infancy to young adulthood including: prenatal drug history, detailed cognitive/behavioral performance, and current and past drug usage. This information allowed for the measurement of an unprecedented number of potentially confounding drug exposure variables including: prenatal marijuana, nicotine, alcohol, and caffeine exposure and offspring alcohol, marijuana, and nicotine use. Ten marijuana users and 14 nonusing controls performed a visuospatial 2-back task while fMRI blood oxygen level-dependent response was examined.

Results

Despite similar task performance, marijuana users had significantly greater activation in the inferior and middle frontal gyri, regions of the brain normally associated with visuospatial working memory. Marijuana users also had greater activation in the right superior temporal gyrus, a region of the brain not typically associated with visuospatial working memory tasks.

Conclusions

These results suggest that marijuana use leads to altered neural functioning during visuospatial working memory after controlling for other prenatal and current drug use. This alteration appears to be compensated for by the recruitment of blood flow in additional brain regions. It is possible that this compensation may not be sufficient in more real-life situations where this type of processing is required and thus deficits may be observed. Awareness of these neural physiological effects of marijuana in youth is critical.

Keywords

Visuospatial working memoryMarijuanaExecutive functioningFunctional magnetic resonance imaging

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Andra M. Smith
    • 1
  • Carmelinda A. Longo
    • 1
  • Peter A. Fried
    • 2
  • Matthew J. Hogan
    • 3
    • 4
  • Ian Cameron
    • 3
    • 4
  1. 1.Department of PsychologyUniversity of OttawaOttawaCanada
  2. 2.Department of PsychologyCarleton UniversityOttawaCanada
  3. 3.Department of Diagnostic ImagingThe Ottawa HospitalOttawaCanada
  4. 4.Ottawa Health Research InstituteOttawaCanada