The Relationship Between Lower Urinary Tract Symptoms and Severity of Alzheimer's Disease

Urinary incontinence (UI) is more prevalent in elderly populations with dementia than those without dementia. Alzheimer's disease (AD) is the most common cause of dementia. Urge UI, the most common type of UI in AD patients, causes more morbidity and mortality. However, it is inconvenient to obtain the report of urodynamic study from AD patient to diagnose urinary incontinence. Nevertheless, it is easier to obtain subjective or objective questionnaires from the patients or the caregivers. The data collected from the questionnaires are used to evaluate if severity of dementia is associated with urge UI and other lower urinary tract symptoms (LUTs).

A total of 43 AD patients were enrolled in this study, all of whom were checked post-void residual (PVR) urine amount by sonography after voiding. The severity of dementia was evaluated by questionnaire including Cognitive Abilities Screening Instrument (CASI), Mini Mental Status Examination (MMSE), Clinical Dementia Rating (CDR), and Clinical Dementia Rating Sub-of-Box (CDR-SB). The LUTs were assessed with International Consultation of Incontinence Questionnaire (ICIQ) and Overactive bladder symptom scores (OABSS) questionnaire. Independent t test and Pearson's correlation analysis were calculated.

The average age in both AD with/without urge UI patients is 78 years old. The scores of CDR-SB, OABSS and ICIQ are significantly different in these 2 groups (p = 0.023, p = 0.003, p = 0.001; respectively). However, the neurophysiological scores of CASI, MMSE, CDR, CDR-SB is not correlated with OABSS (r = 0.047, p = 0.382; r = 0.074, p = 0.317; r = 0.087, p = 0.288; r = 0.112, p = 0.237; respectively). Interestingly, if we separate each individual symptom of OAB, there is a significant correlation between CDR-SB and urge UI score (r = 0.314, p = 0.023).

Higher lower urinary tract symptom scores are noted in AD patients with urge UI. The CDR-SB score is highly correlated with urge UI in AD patients.