I was recently asked about "weak bladders", so I thought I'd write about the two most common types of incontinence, and explain a bit about whether or not a bladder can actually be "weak". The two types of incontinence that people experience most frequently are stress urinary incontinence (SUI), and urge incontinence.
The most common type of incontinence is stress urinary incontinence (SUI). This type of incontinence is caused by weak muscles in the pelvic floor. The pelvic floor muscles form a kind of hammock that hold all the pelvic floor organs, like the bladder, in their proper place. If the muscles get weak and start to sag a big, the sphincter can't close all the way, and urine can leak out. The sphincter is like a clamp that closes off the tube that the urine travels through to leave your body (that tube is called the urethra). Stress incontinence isn't caused by emotional stress. Instead it is caused by physical stress such as coughing, laughing, or sneezing. When your energy is focused elsewhere, and the body is under physical stress, the pelvic floor muscles relax and out comes the urine.
Urge incontinence, on the other hand, is caused usually by a problem with the nerves that are in the bladder wall. Those nerves send a message to the brain as the bladder fills, telling the brain that it is time to urinate. When those nerves aren't working correctly and start sending the message way too often (when the bladder isn't nearly full), it is caused overactive bladder (OAB). When you start feeling a sudden and intense urge to urinate, and can't make it to the bathroom in time and you have an accident, that is called urge incontinence.
So, can incontinence be caused by a weak bladder? Well, it's a little complicated, but usually the answer is no. The bladder is a muscle, and as such, it can become weak. That muscle has to contract to push the urine out when you urinate. If the bladder muscle is weak because you haven't used it enough (you always empty your bladder "just in case", before you actually feel an urge) or if it is weak because it has been over-stretched (you always hold your bladder for a long time), then you may have trouble pushing all the urine out and your bladder will become over-filled and it starts to leak. This is called "overflow incontinence", but it is much rarer than SUI or urge incontinence.
Hopefully that (sort of) answers the question about weak bladders, and gives you a bit more insight into the world of incontinence.