Over the past few years it has become clear that our understanding of bladder physiology is inadequate to explain urge incontinence. This has forced us to re-evaluate what we know and do not know about bladder function and dysfunction. This has led to the identification and study of novel systems within the bladder that may contribute to abnormal sensations.

The investigators now suspect that the organic changes occurring in the bladder are not the whole story. For one group of patients with pathological urge there is growing evidence suggesting that there may be a strong psychological component. The idea now being put forward is that normal afferent peripheral information is perceived as abnormal and excessive, resulting in an increased desire to go to the bathroom: 'perceptual urge'. It is important to identify this group of patients since it will direct their treatment towards more cognitive approaches. Also, if such a psychological aetiology can be eliminated it would lead to a more focused and effective management of peripheral pathology with surgery or pharmacology.

Inclusion Criteria (for patients with OAB):

• Patients older than 18 years with OAB diagnosed by their urologist using the criteria of more than 8 micturitions on three consecutive days of these three days they keep a micturation diary with a VAS score for urge sensation.

Patients should have at least one episode of urge: sudden compelling desire to void which can not be postponed.

• Well versed in Dutch.

Inclusion Criteria (for patients with osteoporosis):

• Patients older than 18 years with osteoporosis joined into the Fast Guide cohort program.
• Well versed in Dutch.

Exclusion Criteria (for patients with OAB):

• Patients with stress-urinary incontinence
• Presence of post void residual urine > 100cc determined by ultrasound
• Presence of urinary tract infection, determined by urine sticks. Patients with urinary tract infection will be treated by antibiotics. After resolution of the infection, the patient can re-enter the study if the urine is sterile at that moment.

Exclusion Criteria (for patients with osteoporosis):

• Urinary complaints or urologic history
• Presence of postvoid residual urine > 100cc determined by ultrasound
• Presence of urinary tract infection, determined by urine sticks. Patients that present with urinary tract infection will be definitively excluded from participation.

The study population consists of two groups: 1: patients with OAB; 2: patients with osteoporosis.

The patients with OAB will be reqruited from the outpatient clinic and website designed for patients with overactive bladder symptoms.

The patients with osteoporosis will be recruited from an electronic patient database.