Overactive bladder (OAB) is a condition characterized by a sudden, uncomfortable need to urinate with or without urine leakage usually with daytime and nighttime frequency.
OAB occurs when smooth muscle of the detrusor muscle of the bladder squeezes or contracts more often than normal and at inappropriate times. Instead of staying at rest as urine fills the bladder, the detrusor contracts while the bladder is filling with urine.

What Causes OAB?

By definition, the cause of OAB is unknown. However, identifiable underlying causes can include: drug side effects, nerve damage or neurological disease (e.g., multiple sclerosis, Parkinson’s disease, etc.) or stroke. There are also conditions that are associated with urgency and frequency – including bladder cancer, urinary tract infections and benign prostatic hyperplasia (BPH) – that must be excluded during an examination.

Some experts believe that some individuals are predisposed to OAB. Circumstantial evidence suggests that individuals with depression, anxiety and attention deficit disorder may experience symptoms of OAB more often than the general population. Some investigators suggest that depression, anxiety, feeding disturbances, pain, irritable bowel syndrome, fibromyalgia and changes in urination are associated with disturbances in brain circuits using specific chemical messengers between nerves known as neurotransmitters, in particular serotonin 5-hydroxytryptamine (5-HT). Fibromyalgia and irritable bowel syndrome are conditions seen more often in patients with OAB and interstitial cystitis (IC) than the general population. These conditions are associated with an overactive bladder and possibly to depression, which provides a potential link with 5-HT metabolism and OAB.