Longitudinal study of hippocampal volumes in heavy cannabis users

L. Koenders*, V. Lorenzetti, L. de Haan, C. Suo, W. A. M. Vingerhoets, W. van den Brink, R. W. Wiers, C. J. Meijer, M. W. J. Machielsen, A. E. Goudriaan, D. J. Veltman, M. Yuecel, J. Cousijn

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Background: Cannabis exposure, particularly heavy cannabis use, has been associated with neuroanatomical alterations in regions rich with cannabinoid receptors such as the hippocampus in some but not in other (mainly cross-sectional) studies. However, it remains unclear whether continued heavy cannabis use alters hippocampal volume, and whether an earlier age of onset and/or a higher dosage exacerbate these changes.

Methods: Twenty heavy cannabis users (mean age 21 years, range 18-24 years) and 23 matched non-cannabis using healthy controls were submitted to a comprehensive psychological assessment and magnetic resonance imaging scan at baseline and at follow-up (average of 39 months post-baseline; standard deviation=2.4). Cannabis users started smoking around 16 years and smoked on average five days per week. A novel aspect of the current study is that hippocampal volume estimates were obtained from manual tracing the hippocampus on T1-weighted anatomical magnetic resonance imaging scans, using a previously validated protocol.

Results: Compared to controls, cannabis users did not show hippocampal volume alterations at either baseline or follow-up. Hippocampal volumes increased over time in both cannabis users and controls, following similar trajectories of increase. Cannabis dose and age of onset of cannabis use did not affect hippocampal volumes.

Conclusions: Continued heavy cannabis use did not affect hippocampal neuroanatomical changes in early adulthood. This contrasts with prior evidence on alterations in this region in samples of older adult cannabis users. In young adults using cannabis at this level, cannabis use may not be heavy enough to affect hippocampal neuroanatomy.

Original languageEnglish
Pages (from-to)1027-1034
Number of pages8
JournalJournal of Psychopharmacology
Issue number8
Publication statusPublished - Aug 2017


  • Cannabis
  • marijuana
  • longitudinal
  • hippocampus
  • manual tracing
  • medial temporal lobe
  • structural MRI
  • DSM-IV

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