Reduced Diffusivity along Perivascular Spaces on MR Imaging Associated with Younger Age of First Use and Cognitive Impairment in Recreational Marijuana Users

Christina Andica; Koji Kamagata; Kaito Takabayashi; Zaimire Mahemuti; Akifumi Hagiwara; Shigeki Aoki

doi:10.3174/ajnr.A8215

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FIG 1.
Flow chart of inclusion and exclusion criteria, along with the count of individuals meeting the criteria and included in the study population. MMSE indicates the Mini-Mental State Examination; DSM-IV, Diagnostic and Statistical Manual of Mental Disorders, 4th edition.
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FIG 2.
Calculation of the DTI index along the perivascular space (ALPS index). A, Color-coded FA map shows the distribution of projection fibers (blue, z-axis) and association fibers (green, y-axis) at the lateral ventricle level of the body. Spherical ROIs measuring 5 mm in diameter were positioned in projection and association areas. The perivascular space runs perpendicular to the projection and association tracts. B, Diffusivity maps in the x-axis (Dxx), y-axis (Dyy), and z-axis (Dzz). C, The ALPS index was derived from the ratio of the mean x-axis diffusivity in the projection area (Dxxproj) and x-axis diffusivity in the association area (Dxxassoc) to the mean of y-axis diffusivity in the projection area (Dyyproj) and z-axis diffusivity in the association area (Dzzassoc).
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FIG 3.
Raincloud plots of ALPS indices (A) among nonusers (individuals with zero lifetime cannabis use) and users (those who reported using marijuana at least once in their lifetime) with different ages of first use and (B) among nonusers and users with various lifetime usage frequencies. The P values correspond to a univariate General Linear Model after controlling for age, sex, years of education, tobacco use, alcohol use, PSQI score, and intracranial volume.