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Regional brain abnormalities associated with heavy long-term cannabis use

Journal Article


Abstract


  • Context: Cannabis is the most widely used illicit drug

    in the developed world. Despite this, there is a paucity

    of research examining its long-term effect on the human

    brain.

    Objective: To determine whether long-term heavy cannabis

    use is associated with gross anatomical abnormalities

    in 2 cannabinoid receptor–rich regions of the brain,

    the hippocampus and the amygdala.

    Design: Cross-sectional design using high-resolution

    (3-T) structural magnetic resonance imaging.

    Setting: Participants were recruited from the general

    community and underwent imaging at a hospital research

    facility.

    Participants: Fifteen carefully selected long-term (10

    years) and heavy (5 joints daily) cannabis-using men

    (mean age, 39.8 years; mean duration of regular use, 19.7

    years) with no history of polydrug abuse or neurologic/

    mental disorder and 16 matched nonusing control subjects

    (mean age, 36.4 years).

    Main Outcome Measures: Volumetric measures of

    the hippocampus and the amygdala combined with measures

    of cannabis use. Subthreshold psychotic symptoms

    and verbal learning ability were also measured.

    Results: Cannabis users had bilaterally reduced hippocampal

    and amygdala volumes (P=.001), with a relatively

    (and significantly [P=.02]) greater magnitude of

    reduction in the former (12.0% vs 7.1%). Left hemisphere

    hippocampal volume was inversely associated with

    cumulative exposure to cannabis during the previous 10

    years (P=.01) and subthreshold positive psychotic symptoms

    (P.001). Positive symptom scores were also associatedwith

    cumulative exposure to cannabis (P=.048).

    Although cannabis users performed significantly worse

    than controls on verbal learning (P.001), this did not

    correlate with regional brain volumes in either group.

    Conclusions: These results provide new evidence of exposure-

    related structural abnormalities in the hippocampus

    and amygdala in long-term heavy cannabis users and

    corroborate similar findings in the animal literature. These

    findings indicate that heavy daily cannabis use across protracted

    periods exerts harmful effects on brain tissue and

    mental health.

UOW Authors


  •   Yucel, Murat (external author)
  •   Solowij, Nadia
  •   Respondek, Colleen M.
  •   Whittle, Sarah (external author)
  •   Fornito, Alex (external author)
  •   Pantelis, Christos (external author)
  •   Lubman, Daniel I. (external author)

Publication Date


  • 2008

Citation


  • Yücel, M., Solowij, N., Respondek, C., Whittle, S., Fornito, A., Pantelis, C. & Lubman, D. I. (2008). Regional brain abnormalities associated with heavy long-term cannabis use. Archives of General Psychiatry, 65 (6), 694-701.

Scopus Eid


  • 2-s2.0-44649187915

Ro Metadata Url


  • http://ro.uow.edu.au/hbspapers/2257

Has Global Citation Frequency


Number Of Pages


  • 7

Start Page


  • 694

End Page


  • 701

Volume


  • 65

Issue


  • 6

Place Of Publication


  • United States

Abstract


  • Context: Cannabis is the most widely used illicit drug

    in the developed world. Despite this, there is a paucity

    of research examining its long-term effect on the human

    brain.

    Objective: To determine whether long-term heavy cannabis

    use is associated with gross anatomical abnormalities

    in 2 cannabinoid receptor–rich regions of the brain,

    the hippocampus and the amygdala.

    Design: Cross-sectional design using high-resolution

    (3-T) structural magnetic resonance imaging.

    Setting: Participants were recruited from the general

    community and underwent imaging at a hospital research

    facility.

    Participants: Fifteen carefully selected long-term (10

    years) and heavy (5 joints daily) cannabis-using men

    (mean age, 39.8 years; mean duration of regular use, 19.7

    years) with no history of polydrug abuse or neurologic/

    mental disorder and 16 matched nonusing control subjects

    (mean age, 36.4 years).

    Main Outcome Measures: Volumetric measures of

    the hippocampus and the amygdala combined with measures

    of cannabis use. Subthreshold psychotic symptoms

    and verbal learning ability were also measured.

    Results: Cannabis users had bilaterally reduced hippocampal

    and amygdala volumes (P=.001), with a relatively

    (and significantly [P=.02]) greater magnitude of

    reduction in the former (12.0% vs 7.1%). Left hemisphere

    hippocampal volume was inversely associated with

    cumulative exposure to cannabis during the previous 10

    years (P=.01) and subthreshold positive psychotic symptoms

    (P.001). Positive symptom scores were also associatedwith

    cumulative exposure to cannabis (P=.048).

    Although cannabis users performed significantly worse

    than controls on verbal learning (P.001), this did not

    correlate with regional brain volumes in either group.

    Conclusions: These results provide new evidence of exposure-

    related structural abnormalities in the hippocampus

    and amygdala in long-term heavy cannabis users and

    corroborate similar findings in the animal literature. These

    findings indicate that heavy daily cannabis use across protracted

    periods exerts harmful effects on brain tissue and

    mental health.

UOW Authors


  •   Yucel, Murat (external author)
  •   Solowij, Nadia
  •   Respondek, Colleen M.
  •   Whittle, Sarah (external author)
  •   Fornito, Alex (external author)
  •   Pantelis, Christos (external author)
  •   Lubman, Daniel I. (external author)

Publication Date


  • 2008

Citation


  • Yücel, M., Solowij, N., Respondek, C., Whittle, S., Fornito, A., Pantelis, C. & Lubman, D. I. (2008). Regional brain abnormalities associated with heavy long-term cannabis use. Archives of General Psychiatry, 65 (6), 694-701.

Scopus Eid


  • 2-s2.0-44649187915

Ro Metadata Url


  • http://ro.uow.edu.au/hbspapers/2257

Has Global Citation Frequency


Number Of Pages


  • 7

Start Page


  • 694

End Page


  • 701

Volume


  • 65

Issue


  • 6

Place Of Publication


  • United States