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Abnormal white matter microstructure present in young adults with psychosis

Recent findings provide evidence that neurodevelopmental factors cause changes in the cellular composition of white matter circuits essential to high cognitive function.

“Understanding the role of [white matter] abnormalities in the development of psychosis necessitates consideration of numerous risk factors, many of which have been implicated in altered microstructure,” Mark Drakesmith, PhD, of Cardiff University Brain Research Imaging Centre, Cardiff University, Wales, and colleagues wrote. “These risk factors include obstetric and developmental factors as well as substance abuse. Reduced IQ in children and adolescents is one such factor and is generally interpreted as evidence of an aberrant neurodevelopmental process. The biological mechanisms whereby such factors contribute to psychosis and how they relate to the brain abnormalities noted above are not clear, and there are most likely multiple pathways.”

To compare white matter microstructure and myelination in young adults with and without psychotic experiences, researchers conducted semi-structured interviews and MRI among 123 individuals with psychotic experiences and 124 controls. Study participants had a mean age of 20 years.

Fractional anisotropy in left frontomedial white matter was significantly reduced in individuals with psychotic experiences (P = .0046).

A continuum-like ordinal model of psychotic experiences indicated a similar but more widespread effect, with an increase in radial diffusivity (P = .0042).

Low birth weight (P = .015) and childhood IQ (P = .003) were associated with psychotic experiences.

Mediation analysis further indicated these associations, in addition to the mediation of psychotic experiences by fractional anisotropy changes in these regions.

“The regions implicated comprise pathways critical to higher order cognitive function. We propose that atypical developmental trajectories contribute to behavioral and cognitive abnormalities, such as those seen in psychosis, via abnormalities in this [white matter] circuitry. We recommend that future studies focus on mediation to further unravel the associations between [psychotic experiences], risk factors for psychosis, and brain structure,” the researchers concluded. – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.