Parkinson’s disease is a progressive neurological disorder known for its impact on movement. However, individuals with Parkinson’s often experience non-motor symptoms. Among these, frequent urination is a common and often distressing issue. This article explores how Parkinson’s disease disrupts normal bladder function, leading to frequent urination.
How the Bladder Normally Works
The bladder functions as a storage reservoir for urine, expanding as it fills and contracting to release urine. This process relies on the coordinated action of the detrusor muscle and two sphincter muscles: the internal and external urethral sphincters. The detrusor muscle relaxes to allow urine storage and contracts to push urine out during urination. The internal sphincter is an involuntary muscle that remains closed during filling and opens during urination, while the external sphincter is under voluntary control for conscious regulation.
Neurological control of the bladder involves the brain, spinal cord, and the autonomic nervous system. Sensory nerves in the bladder wall detect fullness and send signals to the brain, signaling the urge to urinate. During the storage phase, the sympathetic nervous system promotes detrusor muscle relaxation and internal sphincter contraction, preventing urine leakage. When it is time to urinate, the parasympathetic nervous system stimulates the detrusor muscle to contract and the internal sphincter to relax, expelling urine.
How Parkinson’s Affects Bladder Control
Parkinson’s disease results from the degeneration of dopamine-producing neurons, impacting movement. This dopamine deficiency also impacts neural circuits controlling bladder function. The basal ganglia, affected by dopamine loss, normally suppress the urge to urinate. Disrupted inhibitory control due to dopamine depletion can lead to an overactive bladder.
Parkinson’s also affects the autonomic nervous system (ANS), which governs involuntary functions like bladder control. This can lead to neurogenic bladder, a condition where bladder nerves malfunction. This dysfunction can cause problems with urine storage and emptying. Bladder issues are common non-motor symptoms, sometimes appearing early in the disease.
Beyond dopamine, abnormal alpha-synuclein proteins also contribute to bladder dysfunction. These protein clumps affect nerve cells throughout the brain and the autonomic nervous system, disrupting communication pathways that regulate bladder activity. This disruption means the bladder may not receive appropriate signals for relaxation or contraction, leading to uncoordinated function.
Specific Ways Urination Changes
Overactive bladder (OAB) is common, characterized by a sudden, strong urge to urinate that is difficult to postpone. This urgency leads to increased frequency throughout the day, as bladder muscles contract too often or strongly, even when not full. Sometimes, this intense urge results in urine leakage before an individual can reach a restroom, known as urge incontinence.
Frequent nighttime urination, or nocturia, is another prevalent symptom for individuals with Parkinson’s. Individuals often wake multiple times due to a strong urge, disrupting sleep. This happens because bladder capacity is reduced at night or due to impaired signaling that normally prevents contractions during sleep. The combination of urgency and the need to get out of bed quickly in the dark can also increase the risk of falls, especially if Parkinson’s medications have worn off overnight.
In some cases, individuals may also experience difficulty fully emptying their bladder, known as urinary retention. This can happen if the detrusor muscle does not contract strongly enough or if the urethral sphincter muscles fail to relax completely during urination. A sensation of incomplete emptying can result, potentially increasing urinary tract infection risk due to residual urine.
Other Reasons for Frequent Urination
Beyond the direct neurological impact of Parkinson’s, several other factors can contribute to or worsen frequent urination. Mobility challenges can make it difficult for individuals to reach the bathroom in time, especially during sudden urges. This can lead to functional incontinence, where physical limitations prevent timely voiding despite adequate bladder function. Slowness and stiffness can compound the problem, increasing accident risk.
Certain medications for Parkinson’s or other conditions can also influence bladder function. Diuretics increase urine production and can exacerbate urinary frequency. Some anticholinergic medications, while sometimes used to treat Parkinson’s symptoms, can paradoxically affect bladder emptying or increase the risk of urinary retention.
Comorbidities can further contribute to bladder issues in people with Parkinson’s. For men, benign prostatic hyperplasia (BPH) can obstruct urine flow and lead to frequent urination, particularly at night. Urinary tract infections (UTIs) are also more common in individuals with Parkinson’s, especially if bladder emptying is incomplete, and can cause sudden increases in urgency and frequency. Additionally, conditions like diabetes can cause frequent urination due to high blood sugar levels.