JU INSIGHT Structural Changes in Brain White Matter Tracts Associated With Overactive Bladder

By: H. Henry Lai, MD, Washington University School of Medicine, St Louis, Missouri; Jerrel Rutlin, BA, Washington University School of Medicine, St Louis, Missouri; Abigail R. Smith, PhD, Arbor Research Collaborative for Health, Ann Arbor, Michigan; Margaret E. Helmuth, PhD, Arbor Research Collaborative for Health, Ann Arbor, Michigan; James A. Hokanson, PhD, Medical College of Wisconsin, Milwaukee; Claire C. Yang, MD, University of Washington, Seattle; J. Quentin Clemens, MD, University of Michigan, Ann Arbor; Vincent A. Magnotta, PhD, University of Iowa, Iowa City; C. Emi Bretschneider, MD, Northwestern University, Chicago, Illinois; Kimberly Kenton, MD, University of Chicago, Illinois; John O. L. DeLancey, MD, University of Michigan, Ann Arbor; Karen John, BA, Northwestern University, Chicago, Illinois; Ziya Kirkali, MD, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland; Joshua S. Shimony, MD, PhD, Washington University School of Medicine, St Louis, Missouri, for the LURN Study | Posted on: 14 Aug 2024

Lai HH, Rutlin J, Smith AR, et al. Structural changes in brain white matter tracts associated with overactive bladder revealed by diffusion tensor magnetic resonance imaging: findings from a Symptoms of Lower Urinary Tract Dysfunction Research Network cross-sectional case-control study. J Urol. 2024;212(2):351-361. doi:10.1097/JU.0000000000004022

Study Need and Importance

Perception of all bodily sensations occurs in the brain, including the sensation of urinary urgency (UU) in overactive bladder (OAB). In this study, we investigated whether structural disruption of white matter tracts or pathways in the brain may contribute to UU in patients with OAB.

What We Found

Brain diffusion tensor imaging data were compared between 146 participants with OAB and 75 age-matched controls without OAB. Participants with OAB showed greater disruption of brain white matter tracts in anterior thalamic radiations, superior longitudinal fasciculus tracts, and body of corpus callosum compared with controls (red/orange areas in Figure). There was significant correlation between degree of white matter structural disruption (lower fractional anisotropy) and severity of OAB-Questionnaire symptoms (correlation coefficient, R = −0.32, P < .001).

Figure. Diffusion tensor imaging fractional anisotropy (FA) results, overactive bladder vs controls. Left panel, green color indicates P > .05. Red/orange color indicates P < .05, with FA values in overactive bladder statistically lower than controls. Lower FA indicates more structural disruption in white matter tracts. Right panel, negative correlation between FA and Overactive Bladder Questionnaire (OABQ) among overactive bladder participants.

Limitations

This was a cross-sectional study, so we cannot draw causal conclusion. Men were included in the neuroimaging study. Since urodynamics were not performed as part of the neuroimaging study, obstruction could not be ruled out in some men with OAB.

Interpretation for Patient Care

Our study showed that loss of structural integrity of white matter tracts or pathways in the brain may contribute to the pathophysiology of UU in OAB. Study participants did not have a diagnosis of a brain disease (eg, stroke, multiple sclerosis). Instead, OAB patients may have microstructural abnormalities in specific brain white matter tracts that correlated to their UU or OAB symptoms. Our findings suggested a central mechanism or brain-centric mechanism of UU in OAB. Whether or not OAB treatment may reverse these structural changes in the brain is currently unknown. It is possible that microstructural changes in brain nerve fiber tracts, loss of myelination, and axonal degradation continue to deteriorate with time or aging, leading to progression of OAB symptoms with time.