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Mashhoon, Yasmin

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Mashhoon

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Yasmin

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Mashhoon, Yasmin
Author's Publications: search.filters.isAuthorOfPublication.85f8d6d7-a3e2-4bb7-9bf3-1873e81ef558

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    Lower Left Thalamic Myo-Inositol Levels Associated with Greater Cognitive Impulsivity in Marijuana-Dependent Young Men: Preliminary Spectroscopic Evidence at 4T
    (2013) Mashhoon, Yasmin; Jensen, J Eric; Sneider, Jennifer; Yurgelun-Todd, Deborah A; Silveri, Marisa
    The effects of chronic marijuana (MRJ) use on neurochemistry are not well characterized. Previously, altered global myo-Inositol (mI) concentrations and distribution in white matter were associated with impulsivity and mood symptoms in young MRJ-dependent men. The objective of this study was to retrospectively examine previously collected data, to investigate the potential regional specificity of metabolite levels in brain regions densely packed with cannabinoid receptors. Spectra were acquired at 4.0 Tesla using 2D J-resolved proton magnetic resonance spectroscopic imaging (MRSI) to quantify the entire J-coupled spectral surface of metabolites from voxels in regions of interest. For the current regional spectral analyses, a 2D-JMRSI grid was positioned over the central axial slice and shifted in the x and y dimensions to optimally position voxels over regions containing thalamus, temporal lobe, and parieto-occipital cortex. MRJ users exhibited significantly reduced mI levels in the left thalamus (lThal), relative to non-using participants, which were associated with elevated cognitive impulsivity. Other regional analyses did not reveal any significant group differences. The current findings indicate that reduced mI levels are regionally specific to the lThal in MRJ users. Furthermore, findings suggest that mI and the lThal uniquely contribute to elevated impulsivity.
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    A Review of Magnetic Resonance Spectroscopy Studies in Marijuana using Adolescents and Adults
    (2013) Sneider, Jennifer; Mashhoon, Yasmin; Silveri, Marisa
    Marijuana (MJ) remains the most widely used illicit drug of abuse, and accordingly, is associated with adverse effects on mental and physical health, and neurocognitive decline. Studies investigating the neurobiology of underlying MJ effects have demonstrated structural and functional alterations in brain areas that contain moderate to high concentrations of cannabinoid (CB1) receptors and that are implicated in MJ-related cognitive decrements. Proton magnetic resonance spectroscopy (1H MRS), a non-invasive imaging technique used to assess neurochemistry, has been widely applied to probe a variety of substance-abusing populations. To date, however, there is a relative paucity of MRS published studies characterizing changes in neurometabolite concentrations in MJ users. Thus, the current review provides a summary of data from the eight existing MRS studies of MJ use in adolescents and adults, as well as interpretations and implications of study findings. Future MRS studies that address additional factors such as sex differences, onset and duration of use, abstinence and age, are warranted, and would lead to a more thorough characterization of potential neurochemical correlates of chronic MJ use, which would fill critical gaps in the existing literature.
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    Early Versus Late Onset of Cannabis Use: Differences in Striatal Response to Cannabis Cues
    (2017) Wetherill, Reagan R.; Hager, Nathan; Jagannathan, Kanchana; Mashhoon, Yasmin; Pater, Heather; Childress, Anna Rose; Franklin, Teresa R.
    Addiction theories posit that addiction is the result of a progressive transition from voluntary to habitual, compulsive drug use—changes that have been linked, in animals, to a shift from ventral to dorsal striatal control over drug-seeking behavior. Thus, we hypothesized that early-onset (EOs) cannabis users versus late-onset (LOs) cannabis users might exhibit, respectively, greater dorsal versus ventral striatal response to drug cues. We used functional magnetic resonance imaging and an event-related blood oxygen level-dependent backward-masking task to evaluate striatal responses to backward-masked cannabis cues (vs. neutral cues) in EOs (<16 years old, n = 15) and LOs (≥16 years old, n = 26) with similar recent cannabis use patterns. Direct comparisons revealed that EOs showed greater response to cannabis cues in the dorsal striatum than LOs (p < 0.01, k > 50 voxels). Within-group analyses revealed that EOs showed greater neural response to cannabis cues in the dorsal striatum, whereas LOs exhibited greater neural response to cannabis cues in the ventral striatum. Although cross-sectional, these findings are consistent with recent addiction theories suggesting a progressive shift from ventral to dorsal striatal control over drug-seeking behavior and highlight the importance of age of onset of cannabis use on the brain and cognition.