Voiding dysfunction is very common in Alzheimer’s disease, especially urinary incontinence with reported frequencies of 11-90%. Urinary incontinence occurs secondarily from dementia, can result in medical morbidity, impaired self-esteem of the patents, caregiver’s stress, early institutionalization of the patients, and considerable financial cost. Many studies have found that the frequency and severity of incontinence is positively correlated with the severity of dementia and the inability to walk or transfer. Research on the management of urinary incontinence in demented patients has focused almost exclusively on toileting programs and drug treatments for detrusor overactivity. To date, anticholinergic and antispasmodic medications have not been shown to be effective in treating incontinence in demented persons. Therefore we have to study about the etiology and treatment of Alzheimer’s disease.