A New Approach to Studying the Links Between Bladder and Brain Activity in People

Researchers have demonstrated the efficacy of a new, more natural approach to studying bladder function in people. Many studies of people with urologic problems, such as bladder pain or sudden urinary urgency, have involved artificially filling the bladder with liquid using a catheter and simultaneously visualizing brain activity using magnetic resonance imaging (MRI). Such studies have helped identify brain regions and networks involved in perceiving and responding to changes in bladder fullness, in the hope of finding ways to alleviate suffering in people with urologic symptoms that are as yet hard to explain or treat. However, this research approach, while having advantages such as control over the amount of liquid inserted, comes with potential drawbacks—for example, the procedure of catheterization itself can cause discomfort and anxiety in study participants, thereby influencing what is seen in brain scans.

To see whether a more natural bladder-filling strategy would be viable and possibly superior as a study method, researchers in the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network studied the brain’s response to natural bladder filling in study participants without urologic problems. Sixty-two healthy men and women were asked to drink about 12 ounces of water after first voiding their bladders; 40 minutes later, they underwent an MRI brain scan for 10 minutes, emptied their bladders into a urine collection container, and underwent a second 10 minute scan. Participants were also asked to report the degree of urgency they felt at different times during the procedure—just after drinking the water, 20 minutes later, and both before and after each MRI scan. The majority of participants responded to the test procedure with an increasing feeling of urinary urgency that peaked by the end of the first scan and was relieved when they voided. More intense feelings of urgency correlated with larger void volumes--a proxy measure of bladder fullness. The researchers found that activity in specific brain regions and networks associated with bladder filling and voiding--from sensory recognition to physical response--not only was detectable, but also correlated with perceived urinary urgency and with void volumes.

This study provides proof that a more natural bladder filling method that avoids invasive catherization is effective for studying brain activities important to urologic function and correlating them with people’s symptom experiences. Such an approach should be easier to implement and help researchers perform studies in larger and more diverse groups of people. Already, it is being used to study symptomatic participants in the MAPP Research Network, and should advance overall efforts to study people with underlying urologic diseases, disorders, and symptoms.