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An MRI study of white matter tract integrity in regular cannabis users: Effects of cannabis use and age
Jakabek, David Yucel, Murat Lorenzetti, Valentina Solowij, Nadia
Jakabek, David
Yucel, Murat
Lorenzetti, Valentina
Solowij, Nadia
Abstract
Rationale Conflicting evidence exists on the effects of cannabis use on brain white matter integrity. The extant literature has exclusively focused on younger cannabis users, with no studies sampling older cannabis users. Objectives We recruited a sample with a broad age range to examine the integrity of major white matter tracts in association with cannabis use parameters and neurodevelopmental stage. Methods Regular cannabis users (n = 56) and non-users (n = 20) with a mean age of 32 (range 18–55 years) underwent structural and diffusion MRI scans. White matter was examined using voxel-based statistics and via probabilistic tract reconstruction. The integrity of tracts was assessed using average fractional anisotropy, axial diffusivity and radial diffusivity. Diffusion measures were compared between users and non-users and as group-by-age interactions. Correlations between diffusion measures and age of onset, duration, frequency and dose of current cannabis use were examined. Results Cannabis users overall had lower fractional anisotropy than healthy non-users in the forceps minor tract only (p = .015, partial eta = 0.07), with no voxel-wise differences observed. Younger users showed predominantly reduced axial diffusivity, whereas older users had higher radial diffusivity in widespread tracts. Higher axial diffusivity was associated with duration of cannabis use in the cingulum angular bundle (beta = 5.00 × 10−5, p = .003). Isolated higher AD in older cannabis users was also observed. Conclusions The findings suggest that exogenous cannabinoids alter normal brain maturation, with differing effects at various neurodevelopmental stages of life. These age-related differences are posited to account for the disparate results described in the literature.
Keywords
cannabis, brain, diffusion tensor imaging, magnetic resonance imaging, tractography, white matter
Date
2016
Type
Journal article
Journal
Psychopharmacology
Book
Volume
233
Issue
19-20
Page Range
3627-3637
Article Number
ACU Department
School of Behavioural and Health Sciences
Faculty of Health Sciences
Faculty of Health Sciences
Relation URI
Source URL
Event URL
Open Access Status
License
File Access
Controlled