MICHAEL PERELMAN, PhD: They can run the whole gamut. I think part of what we're seeing here is really the intelligence of the patients in recognizing that if you have a prostate cancer surgery and subsequently find yourself unable to get an erection, it's a good idea to go back to that surgeon and also speak to a urologist and have full medical consultation. However, so many men as they age presume erroneously that they're supposed to have automatic erections. They're supposed to be looking at their partner with the same degree of excitement and interest that they used to have and spontaneously have an erection as if it's some kind of peter meter. So the most common cause of erectile dysfunction is essentially insufficient stimulation. We don't get the direct friction, if you will, to our penis that we need in order to obtain and maintain the erection.
Fatigue is another common cause of erectile dysfunction. When people say, "Hey, I'm just too tired. It's not just some lame excuse. It's a reality because that effects your physical capacity.
The same thing with negative thinking. So relationship issues can somehow impede a couple's ability to be able to function completely and correctly.
There are some other more deeper, if you will, psychological causes, but the most common ones are really insufficient stimulation, negative thinking and fatigue.
DAVID FOLK THOMAS: Do we know what percentage of patients with erectile dysfunction -- is it caused by psychological or physiological?
