Effects of biofeedback-based sleep improvement program on urinary symptoms and sleep patterns of elderly Korean women with overactive bladder syndrome

Sleep disorders in elderly individuals with overactive bladder syndrome (OAB) are a common problem. The prevalence of OAB in elderly individuals in the United States and Europe is 16.9 and 11.8%, respectively [1, 2]. OAB is characterized by major lower urinary tract dysfunction that causes urinary frequency, nocturia, and urinary urgency irrespective of urge incontinence [3]. Its prevalence increases with age [2] and lower physical activity [4] and is higher in females than in males [1]. Nocturia is the most uncomfortable lower urinary tract symptom in elderly individuals; it directly causes sleep disturbances and increases the risk of falls and fractures [5]. Frequent awakening due to symptoms of OAB disturbs the quality of sleep, resulting in severe fatigue in daytime activities [6].

The cause of OAB has not been identified yet; however, one or more physiological changes are thought to play a role in its development [7]. OAB without the presence of a neurological disease has been attributed to autonomic nervous system (ANS) abnormalities based on the role of the ANS in regulating bladder function [8]. The parasympathetic nervous system induces bladder contractions, while the sympathetic nervous system regulates the contractions of the bladder neck and urethral smooth muscle and relaxation of the bladder body [9]. Therefore, ANS imbalances can result in abnormal bladder activity [8].

Although elderly individuals can suffer from sleep disorders secondary to OAB, aging itself causes ANS changes, leading to increased and decreased activities of the sympathetic and parasympathetic nervous systems, respectively, thereby lowering the sleep quality [10]. Excessive sympathetic nervous system activity leads to frequent awakening and interferes with deep sleep, suggesting that sleep interventions in elderly women should be directed towards maintaining balance in the ANS [11, 12].

However, active efforts to solve such problems are lacking because most patients tend to perceive this issue as a natural phenomenon due to aging. Few studies have examined the management of symptoms in the elderly at the physiological level and few interventions are available to address sleep disorders. Sleep disorders are often considered characteristic of elderly patients. Additionally, there are limited drug therapies that can be used to improve sleep problems in elderly people with OAB. Anti-muscarinic drugs are the most commonly used ones in the treatment of OAB; however, long-term adherence to the management is very low due to the side effects, such as constipation and dry mouth [13, 14]. Particularly, elderly patients may be on multiple drugs for various comorbidities; therefore, care must be taken in prescribing these drugs. For this reason, several studies have suggested that multicomponent treatment should be considered as the first-line therapy for OAB in elderly people [15, 16].

In this study, we aimed to use mechanism-based interventions to improve sleep in elderly people with OAB and focused on using mechanisms to balance the ANS. A therapeutic approach towards balancing the ANS is essential to be an effective sleep intervention in elderly patients with OAB. The use of biofeedback from the sympathetic and parasympathetic nervous systems to balance the ANS appears to be an important approach in alleviating the symptoms of OAB. Additionally, biofeedback has been reported to be not only an effective intervention in patients with physical and psychological disorders secondary to ANS imbalances but also a suitable sleep intervention as well [17].

In the literature, changes in autonomic functions might be the underlying cause of OAB and lowered sleep quality. OAB also could be one of the major factors that interfere with deep sleep in the elderly. Therefore, we hypothesized that stabilizing the autonomic functions might reduce the symptoms of OAB and improve sleep.

Twenty elderly women with OAB treated with the BBSI program (BBSI group) and 18 with OAB without the BBSI program (control group) were included in the present study. The patients’ basic characteristics, clinical and laboratory parameters of ANS activity, OAB symptoms, and sleep patterns are summarized in Table 1. The mean age in the BBSI group and control group was 80.05 ± 4.21 and 81.06 ± 4.32 years, respectively. There were no intergroup differences in the educational level, marital status, monthly income, parity, caffeine intake, water intake, BMI, or OAB duration. Regarding the parameters of HRV, catecholamines, OAB symptoms, and sleep patterns did not differ between the groups.

The effects of the 12-week BBSI program on the HRV parameters and plasma catecholamine levels are summarized in Table 2. Significant decreases were observed in RMSSD (37.02 ± 35.56 vs. 51.93 ± 49.61, p = 0.025), LF/HF ratio (2.59 ± 2.23 vs. 1.03 ± 0.27, p = 0.006), and epinephrine levels (42.31 ± 13.58 vs. 34.69 ± 12.83, p = 0.039) in the BBSI group after the intervention, whereas SDNN, TP, LF, and HF did not differ after the intervention. All the parameters related to HRV and plasma catecholamine levels in the control group did not change in the control group after the 12-week period.

The effects of the 12-week BBSI intervention on OAB symptoms measured by OAQ-q are summarized in Table 3. At baseline, no significant difference was found in the frequency, urgency, nocturia, or urgency incontinence between the patients and controls (Table 1). After the 12-week intervention, the BBSI group demonstrated a significant improvement in the urgency score (8.5 ± 1.5 vs. 7.5 ± 0.82, p = 0.004), nocturia (9.35 ± 2.08 vs. 6.85 ± 1.42, p < 0.001), and total score (48.81 ± 10.59 vs. 33.96 ± 7.31, p < 0.001).

Table 4 shows that, regarding sleep patterns, in the BBSI group, we observed a significant difference in SE, WASO, number of awakenings, and number of awakenings within three hours after sleep onset (p = 0.004, p = 0.001, p = 0.001, and p = 0.048, respectively).

In this study, we aimed to develop, apply, and analyze the efficacy of a BBSI program in elderly women with OAB who were assumed to have an overall ANS imbalance due to excessive sympathetic activity. The program included biofeedback training using HRV, lifestyle modifications, physical activity, depression management, sleep hygiene, and PFM exercises. After the 12-week program, RMSSD—a key indicator of HRV—had increased significantly, while the LF/HF ratio and epinephrine secretion decreased significantly. Furthermore, OAB symptoms had alleviated. These results improved sleep by decreasing WASO, number of awakenings during sleep, number of awakenings within 3 h of sleep onset, and increasing sleep efficiency (SE).

Notable results of this study were that post-intervention RMSSD in the experimental group increased significantly, whereas the post-intervention LF/HF ratio decreased significantly. No differences were observed in these indicators in the control group after completion of the study. Biofeedback using HRV effectively treated the psychological issues, such as depression, panic, and insomnia through ANS balance [17]. The ANS also demonstrated other benefits, such as decreased pulse, increased body temperature, and improved blood circulation [37].

According to previous studies in females with OAB, the LF/HF ratio is significantly increased when the bladder is full [38, 39]. Hsiao et al. emphasized that the sympathetic nervous system is relatively overactive in OAB because the LF/HF ratio is higher in women with OAB than that in healthy adults, even when the bladder is empty [40]. Similarly, Choi et al. [41] reported that HF—a frequency domain indicator of RMSSD and parasympathetic nerve activity—was decreased in women with OAB compared to healthy adults. RMSSD increased and LF/HF ratio decreased after the intervention in this study—a finding that was consistent with ANS changes that may help alleviate OAB symptoms. Furthermore, Hubeaux et al. suggested that ANS dysfunction due to sympathetic predominance may be implied in the generation of abnormal bladder sensations, such as urgency [38, 39]. In contrast, increased parasympathetic nerve activity has been reported as a cause of OAB [7, 42] or nocturia [43]. There are differences in the participants and data collection methods in these studies; therefore, direct comparison is difficult. However, our biofeedback protocol was designed to activate the parasympathetic nerves while keeping the LF/HF ratio at an appropriate value during biofeedback training, which may have been an important factor in alleviating OAB symptoms. Considering the results of previous studies, the results of this study confirm the possibility of ANS imbalance due to sympathetic dominance as the cause of OAB. ANS changes associated with senescence involve increase and decrease in the activities of the sympathetic and parasympathetic nervous systems, respectively [10, 44]. Such changes lead to sleep disturbances, including frequent awakening and reduced rapid eye movement (REM) sleep [44]. In one study, RMSSD was reported to be lower in elderly individuals than that in younger individuals, and this finding was more common in females [45]. Therefore, increased RMSSD may induce deep sleep and stabilize sleep structure. Further, serum epinephrine was significantly reduced after 12 weeks in the BBSI group. The LF/HF ratio is well-known to better reflect sympathetic nervous system balance than any other single indicator [30], whereas the circulating epinephrine level is directly related to sympathetic activity. Therefore, serum epinephrine level is a powerful tool for evaluating the program efficacy.

Urinary symptom severity was significantly decreased in the experimental group, while no differences were noted in the control group. Symptoms of OAB are directly affected by changes in sleep structure due to aging, such as decreased REM and slow wave sleep [5]. Active interventions for these direct factors play an important role in improving sleep in elderly individuals [46]. The primary intervention for alleviating urinary symptoms is behavioral therapy, especially in elderly patients. This treatment is safer and has fewer side effects than drug therapy or surgery [47, 48] and has better subjective assessment of symptoms than drug therapy [49].

Few previous studies have focused on ANS as a mediator in the relief of OAB symptoms. Cho et al. [50] attempted to alleviate OAB symptoms by inducing ANS changes using Tai-chi. No change in ANS activity was observed but urinary symptoms were alleviated without improvement in nocturia [50]. However, in the present study, nocturia and urgency were improved—but not frequency and urgency incontinence. We believe that this difference in the outcome was due to the focus of the intervention. In OAB patients—especially those with urgency incontinence—it is important to acquire skills to respond to urgency situations, such as PFM contraction and relaxation techniques [48]. However, the intervention program of this study was composed mainly of factors that reduce nocturia by emphasizing the practice of sleep hygiene—including water and caffeine restriction—urination before bedtime, and performing appropriate exercise to reduce awakening. These results indicate that urinary symptoms are related to several factors and that a customized intervention for each symptom is necessary for symptomatic relief [47].

In this study, SE increased, while wakefulness after sleep onset, number of awakenings during sleep, and number of awakenings within 3 h after sleep onset decreased, and overall sleep improved in the experimental group after the program. In elderly women with OAB, SE reduced and WASO increased significantly due to decreased urinary symptoms and exacerbated changes that occur during the normal aging process [5, 51]. Furthermore, since sympathetic nervous activity may affect REM sleep and induce nocturia [52], these results suggest that increasing RMSSD and decreasing the LF/HF ratio improves sleep in elderly women with OAB. Particularly, lower sleep quality due to nocturia is a problem due to which patients with OAB are the most inconvenienced [53]. Decreased wakefulness after sleep onset is associated with reduced nocturnal enuresis. Additionally, the frequency of awakening due to urination in the initial stages of sleep is a key parameter for clinically assessing the quality of sleep and life [54]. The frequency of awakening during sleep is known to increase with age and this frequency is important in terms of sleep quality in elderly individuals with OAB because it can be difficult to return to sleep after awakening [55]. The elderly demonstrate slow sleep—which is deep sleep for 3 h after sleep onset—during which arousal has the greatest effect on daytime drowsiness and disruption of daily activities [56]. The decrease in awakening frequency seems to positively affect sleep quality by increasing sleep continuity.

This study introduced a method to effectively treat sleep disorders using a program that addresses the physiological issues to alter ANS imbalances. A strong point of the program is that it addresses the issue integrally by approaching sleep disruption in view of the characteristics of OAB. Additionally, as an early study of sleep problems in patients with OAB, considerable results were obtained that confirm that ANS stabilization is effective in improving OAB and sleep. Based on the results of this study, it also may be possible to apply ANS stabilization to OAB patients more easily in daily life, such as relaxation and meditation therapy [57].

Despite the strengths, the study has some limitations. First, the study has the potential for bias due to the use of a non-randomized controlled trial design and no blinding between the researchers and participants. Second, HRV measurements—reflecting ANS—were evaluated during daytime stability and do not reflect changes in sleep and bladder activity at other times of the day. Third, the findings should be generalized with caution as there is the possibility of interference from external variables and the fact that only two senior welfare centers in Korea were included. Finally, it is difficult for the participants to apply the BBSI program’s protocol to their daily life on their own. Further studies with larger samples with randomized control trial designs and direct ANS activity measurements are needed to evaluate the precise relationships between ANS activity, bladder activity, and sleep patterns. Additionally, simplifying the elements of the program and making it easier to apply in everyday life will help the participants manage the disorders on their own.

This study tested a BBSI program in elderly women with OAB in a coordinated manner and demonstrated that the program could improve ANS balance, alleviate urinary symptoms, and improve sleep. The results of this intervention study demonstrate that it is meaningful to consider physiological factors in sleep interventions. Therefore, the program is expected to positively affect the quality of sleep and life in elderly women with OAB.