Urgency urinary incontinence (UUI), a form of overactive bladder (OAB), is prevalent (36% of women over age 65), morbid and costly ($83 billion/year), and treatment is problematic. Current treatment is largely bladder centric has limited efficacy,and adherence rates fade to 21% at 12 months. The researchers believe that a complimentary approach, one that also addresses etiology beyond the bladder may enhance treatment success. Up to 50% of older adults complain of poor sleep and nighttime bladder symptoms (nocturia) are considered the major cause. However, the relationship between sleep and the bladder is complex and bidirectional. Poor sleep not only exacerbates daytime lower urinary tract symptoms (LUTS), but can also cause these, increasing the risk of LUTS by up to 55% over 5 years. Sleep disruption increases anxiety and impairs daytime attention, both of which affect bladder control. Consistent with findings in anxiety disorders and attention control, poor sleep is linked to media prefrontal cortex (mPFC) hypoactivity, a region the investigators have identified as key to executive control of voiding and to therapeutic response to biofeedback-assisted pelvic floor muscle therapy. Hence, the investigators posit that enhanced mPFC function through improved sleep might ameliorate bladder control. Despite evidence of a bidirectional relationship, the impact of sleep treatment on UUI has never been assessed. The researchers prior study demonstrated that improving sleep using Brief Behavioral Treatment of Insomnia (BBTI), a simple intervention for insomnia, improved both sleep and nocturia in older adults, yet its impact on UUI and mechanism of action is not known. Our exploratory analysis of sleep and voiding data from 20 older adults with UUI and nocturia showed that with behavioral sleep intervention alone, 24-hour UUI episodes decreased with prolongation of uninterrupted sleep before the first awakening to void (r=-0.50, p=0.02), and increased proportion of deep sleep (r=-0.56, p=0.01). Hence, the researchers postulate that addressing sleep in patients with UUI and nocturia may further potentiate bladder-focused UUI treatment. The efficacy of mirabegron, a β3- adrenoceptor agonist is comparable to first-line antimuscarinic pharmacotherapy for UUI, with fewer side effects, but it has only a modest effect on nocturia. Although these drugs show statistically significant improvement in LUTS, drug compliance remains poor secondary to modest perceived clinical benefit. The researchers central hypothesis is that comorbid insomnia contributes to poor therapeutic response for UUI and concurrent insomnia treatment will improve outcomes. Specifically, addition of BBTI to drug therapy will improve sleep, nocturia, and daytime LUTS, likely mediated by improvement of mPFC function.

The researchers propose an 8-week randomized controlled trial of mirabegron+BBTI vs. mirabegron alone for UUI in 100 women (aged ≥60), assessing both clinical and neural effects of treatment. The researchers will also assess durability of the combination therapy at 6 months. This design encompasses the role of sleep in OAB treatment, insight into the central and peripheral effects of mirabegron and BBTI, and response durability.