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Multimodal neuroimaging of frontal white matter microstructure in early phase schizophrenia: the impact of early adolescent cannabis use.

Bernier D, Cookey J, McAllindon D, Bartha R, Hanstock CC, Newman AJ, Stewart SH, Tibbo PG - BMC Psychiatry (2013)

Bottom Line: White matter, which comprises axons and their myelin sheaths, provides the physical foundation for functional connectivity in the brain.These four neuroimaging indices will be assessed within the same brain region of interest, that is, a large white matter fibre bundle located in the frontal region, the left superior longitudinal fasciculus.We will expand our knowledge regarding current theoretical models of schizophrenia with a more comprehensive multimodal neuroimaging approach to studying the underlying cellular abnormalities of white matter, while taking into consideration the important confounding variable of early adolescent onset of regular cannabis use.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Psychiatry, Dalhousie University, 5909 Veterans' Memorial Lane, Abbie J, Lane Building, Room 3030, Halifax B3H 2E2, Nova Scotia, Canada. dcbernie@dal.ca.

ABSTRACT

Background: A disturbance in connectivity between different brain regions, rather than abnormalities within the separate regions themselves, could be responsible for the clinical symptoms and cognitive dysfunctions observed in schizophrenia. White matter, which comprises axons and their myelin sheaths, provides the physical foundation for functional connectivity in the brain. Myelin sheaths are located around the axons and provide insulation through the lipid membranes of oligodendrocytes. Empirical data suggests oligodendroglial dysfunction in schizophrenia, based on findings of abnormal myelin maintenance and repair in regions of deep white matter. The aim of this in vivo neuroimaging project is to assess the impact of early adolescent onset of regular cannabis use on brain white matter tissue integrity, and to differentiate this impact from the white matter abnormalities associated with schizophrenia. The ultimate goal is to determine the liability of early adolescent use of cannabis on brain white matter, in a vulnerable brain.

Methods/design: Young adults with schizophrenia at the early stage of the illness (less than 5 years since diagnosis) will be the focus of this project. Four magnetic resonance imaging measurements will be used to assess different cellular aspects of white matter: a) diffusion tensor imaging, b) localized proton magnetic resonance spectroscopy with a focus on the neurochemical N-acetylaspartate, c) the transverse relaxation time constants of regional tissue water, d) and of N-acetylaspartate. These four neuroimaging indices will be assessed within the same brain region of interest, that is, a large white matter fibre bundle located in the frontal region, the left superior longitudinal fasciculus.

Discussion: We will expand our knowledge regarding current theoretical models of schizophrenia with a more comprehensive multimodal neuroimaging approach to studying the underlying cellular abnormalities of white matter, while taking into consideration the important confounding variable of early adolescent onset of regular cannabis use.

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Water signal decay curve. Note. Water signal areas are fitted to a two-component decay model using MATLAB.
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Figure 4: Water signal decay curve. Note. Water signal areas are fitted to a two-component decay model using MATLAB.

Mentions: Area under the water signal is calculated from the frequency domain at each TE, using a MATLAB script ([98]. From the decrease in water signal amplitude as a function of TE, the corresponding T2 relaxation time constants are estimated as a curve fit of a two-component exponential decay using the Curve Fitting Tool in MATLAB. The decay curve of water could potentially involve three components: CSF (long T2), tissue water (intermediate T2), and myelin water (very short T2) [87]. With this study design however, signals from myelin water mostly decayed at the echo times sampled; the very short myelin component is therefore not identified by the fitting algorithm. As for NAA levels, signal loss (as a function of TE) has a better fit with a mono-exponential decay curve [99] (FiguresĀ 3 and 4).


Multimodal neuroimaging of frontal white matter microstructure in early phase schizophrenia: the impact of early adolescent cannabis use.

Bernier D, Cookey J, McAllindon D, Bartha R, Hanstock CC, Newman AJ, Stewart SH, Tibbo PG - BMC Psychiatry (2013)

Water signal decay curve. Note. Water signal areas are fitted to a two-component decay model using MATLAB.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3852698&req=5

Figure 4: Water signal decay curve. Note. Water signal areas are fitted to a two-component decay model using MATLAB.
Mentions: Area under the water signal is calculated from the frequency domain at each TE, using a MATLAB script ([98]. From the decrease in water signal amplitude as a function of TE, the corresponding T2 relaxation time constants are estimated as a curve fit of a two-component exponential decay using the Curve Fitting Tool in MATLAB. The decay curve of water could potentially involve three components: CSF (long T2), tissue water (intermediate T2), and myelin water (very short T2) [87]. With this study design however, signals from myelin water mostly decayed at the echo times sampled; the very short myelin component is therefore not identified by the fitting algorithm. As for NAA levels, signal loss (as a function of TE) has a better fit with a mono-exponential decay curve [99] (FiguresĀ 3 and 4).

Bottom Line: White matter, which comprises axons and their myelin sheaths, provides the physical foundation for functional connectivity in the brain.These four neuroimaging indices will be assessed within the same brain region of interest, that is, a large white matter fibre bundle located in the frontal region, the left superior longitudinal fasciculus.We will expand our knowledge regarding current theoretical models of schizophrenia with a more comprehensive multimodal neuroimaging approach to studying the underlying cellular abnormalities of white matter, while taking into consideration the important confounding variable of early adolescent onset of regular cannabis use.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Psychiatry, Dalhousie University, 5909 Veterans' Memorial Lane, Abbie J, Lane Building, Room 3030, Halifax B3H 2E2, Nova Scotia, Canada. dcbernie@dal.ca.

ABSTRACT

Background: A disturbance in connectivity between different brain regions, rather than abnormalities within the separate regions themselves, could be responsible for the clinical symptoms and cognitive dysfunctions observed in schizophrenia. White matter, which comprises axons and their myelin sheaths, provides the physical foundation for functional connectivity in the brain. Myelin sheaths are located around the axons and provide insulation through the lipid membranes of oligodendrocytes. Empirical data suggests oligodendroglial dysfunction in schizophrenia, based on findings of abnormal myelin maintenance and repair in regions of deep white matter. The aim of this in vivo neuroimaging project is to assess the impact of early adolescent onset of regular cannabis use on brain white matter tissue integrity, and to differentiate this impact from the white matter abnormalities associated with schizophrenia. The ultimate goal is to determine the liability of early adolescent use of cannabis on brain white matter, in a vulnerable brain.

Methods/design: Young adults with schizophrenia at the early stage of the illness (less than 5 years since diagnosis) will be the focus of this project. Four magnetic resonance imaging measurements will be used to assess different cellular aspects of white matter: a) diffusion tensor imaging, b) localized proton magnetic resonance spectroscopy with a focus on the neurochemical N-acetylaspartate, c) the transverse relaxation time constants of regional tissue water, d) and of N-acetylaspartate. These four neuroimaging indices will be assessed within the same brain region of interest, that is, a large white matter fibre bundle located in the frontal region, the left superior longitudinal fasciculus.

Discussion: We will expand our knowledge regarding current theoretical models of schizophrenia with a more comprehensive multimodal neuroimaging approach to studying the underlying cellular abnormalities of white matter, while taking into consideration the important confounding variable of early adolescent onset of regular cannabis use.

Show MeSH
Related in: MedlinePlus