Isn't the reasons for erectile dysfuntion something like 85 percent psychological? Cant remember the source. Anyone got the stats?
Highly variable. The older you get the more likely it is to be organic. In case you're interested, in organic impotence there are no spontaneous early morning erections, whereas if the cause is more psychological there generally are. I tend to use that as a screening question.
Of course, Viagra will also have a large placebo effect, so may also be useful in psychological impotence too.
QDM