Deficits in neurite density underlie white matter structure abnormalities in first-episode psychosis

Rae, Charlotte, Davies, Geoff, Garfinkel, Sarah, Gabel, Matthew, Dowell, Nicholas, Cercignani, Mara, Seth, Anil, Greenwood, Kathryn, Medford, Nick and Critchley, Hugo (2017) Deficits in neurite density underlie white matter structure abnormalities in first-episode psychosis. Biological Psychiatry. ISSN 0006-3223

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Abstract

Background: Structural abnormalities across multiple white matter tracts are recognised in people with early psychosis, consistent with dysconnectivity as a neuropathological account of symptom expression. We applied advanced neuroimaging techniques to characterise microstructural white matter abnormalities for a deeper understanding of the developmental aetiology of psychosis.

Methods: Thirty-five first-episode psychosis patients, and 19 healthy controls, participated in a quantitative neuroimaging study using Neurite Orientation Dispersion and Density Imaging (NODDI), a multi-shell diffusion-weighted MRI technique that distinguishes white matter fibre arrangement and geometry from changes in neurite density. Fractional anisotropy (FA) and mean diffusivity images were also derived. Tract-based spatial statistics compared white matter structure between patients and controls and tested associations with age, symptom severity and medication.

Results: Patients with first-episode psychosis had lower regional FA in multiple commissural, corticospinal, and association tracts. These abnormalities predominantly colocalized with regions of reduced neurite density, rather than aberrant fibre bundle arrangement (orientation dispersion index). There was no direct relationship with active symptomatology. FA decreased and orientation dispersion index increased with age in patients, but not controls, suggesting accelerated effects of white matter geometry change.

Conclusions: Deficits in neurite density appear fundamental to abnormalities in white matter integrity in early psychosis. In the first application of NODDI in psychosis, we found that processes compromising axonal fibre number, density, and myelination, rather than processes leading to spatial disruption of fibre organisation, are implicated in the aetiology of the disorder. This accords with a neurodevelopmental origin of aberrant brain-wide structural connectivity predisposing individuals to psychosis.

Item Type: Article
Schools and Departments: Brighton and Sussex Medical School > Neuroscience
School of Engineering and Informatics > Informatics
Research Centres and Groups: Sackler Centre for Consciousness Science
Subjects: Q Science > QM Human anatomy > QM0531 Regional anatomy
Depositing User: Charlotte Rae
Date Deposited: 13 Feb 2017 14:56
Last Modified: 19 Aug 2017 09:58
URI: http://sro.sussex.ac.uk/id/eprint/66732

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