Brain activity underlying impaired continence control in older women with overactive bladder.

AIMS: To identify, in subjects with overactive bladder (OAB), differences in brain activity between those who maintained and those who lost bladder control during functional magnetic resonance imaging (fMRI) of the brain with simultaneous urodynamics.
METHODS: Secondary analysis of a cohort of older women (aged >60) with proven urgency urinary incontinence, who, in the scanner, either developed detrusor overactivity and incontinence (the "DO group") or did not (the "no DO" group). A priori hypothesis: during urgency provoked by bladder filling, without DO, activity in regions related to continence control is diminished in the DO group; specifically (1a) less activation in supplementary motor area (SMA) and (1b) less deactivation in prefrontal cortex (PFC) and parahippocampal complex (PH). We also explored phenotypic (clinical and urodynamic) differences between the groups.
RESULTS: During urgency preceding DO, the DO group showed stronger activation in SMA and adjacent regions (hypothesis 1a rejected), and less deactivation in PH but no significant difference in PFC (hypothesis 1b partially accepted). These subjects were older, with more changes in brain's white matter, decreased tolerance of bladder filling and greater burden of incontinence.
CONCLUSIONS: (1) In older women with OAB, brain activity in the SMA is greater among those with more easily elicitable DO, suggesting a compensatory response to failure of control elsewhere. (2) OAB is heterogeneous; one possible phenotype shows severe functional impairment attributable partly to age-related white matter changes. (3) Functional brain imaging coupled with urodynamics may provide CNS markers of impaired continence control in subjects with OAB.