White matter pathology is shared across multiple psychiatric brain disorders: Is abnormal diffusivity a transdiagnostic biomarker for psychopathology?

Background

Neuroimaging methods have become important techniques for exploring the neurobiology of neuropsychiatric disorders before and after treatment. Diffusion Tensor Imaging (DTI), has emerged as a propitious tool for the detection of neurological pathology in a variety of psychiatric syndromes. DTI measures the dispersion of water molecules, giving insight into white matter (WM) integrity. We conducted a selective review of the literature to determine WM pathology across major psychiatric brain disorders, as measured by DTI.

Methods

An online search was conducted to identify systematic reviews and metaanalysis published from January 2010 to September 2019 that assessed the WM integrity in several neuropsychiatric disorders. We examined the WM pathologies in different brain regions to detect patterns that may be common among those disorders.

Results

Studies in schizophrenia, bipolar disorder, major depressive disorder, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, borderline personality, post-traumatic stress disorder, and Alzheimer’s disease all demonstrate decreased diffusivity as measured by fractional anisotropy (FA). A common location for WM pathology in all disorders was found within the commissural fibers of the corpus callosum (CC). Nonetheless, the heterogeneity of these disorders is highlighted, as patients present with different locations for WM pathology.

Conclusions

Our selective review suggests that many neuropsychiatric disorders have underlying WM pathology on DTI, specifically a decrease in diffusivity. Measuring WM pathology using DTI is emerging as a useful tool for identifying individuals with various psychopathologies and may lead to early diagnosis and treatment. Finally, the mechanisms by which WM pathology may contributes to the generation of psychiatric signs and symptoms requires further investigation.