Most commonly, ED is vasculogenic (caused by impaired blood flow into the corpora cavernosa of the penis). This happens with age, high cholesterol, high blood pressure, diabetes, or other causes of vascular disease, as well as certain medications. Patients with vasculogenic ED should be evaluated for possible vascular issues, including heart disease. This can be done by a primary care physician.
ED can also be neurogenic, meaning caused by damage to the nerves that initiate blood flow to the penis. This can happen with diabetes or back injuries. Additionally, neurogenic ED is common in men who have been treated for prostate cancer. All prostate cancer treatments can potentially cause neurogenic ED.
The third type of ED is psychogenic. This happens when arousal is impaired due to psychological factors. This is commonly due to performance anxiety & is the most common cause of ED in young patients. That being said, psychological factors can contribute to ED in any man. Basically, if you are thinking about whether or not your erection is going to work rather than focusing on your partner, you are out of the game.
Although low testosterone is not generally a direct cause of ED, it can cause decreased interest in sex,
which can secondarily impair erections. A critical amount testosterone is generally required for good erections.