Between 15 and 30 million men suffer from some form of impotence or erectile dysfunction. At first glance this range seems wide, but it's due to the fact that some health professionals use the term "impotence" to include a host of sexual problems in men—not just the total inability to have or maintain an erection.

Other symptoms include occasionally having problems getting an erection or being unable to control ejaculation. According to the American Urology Association, most men have difficulty achieving erections at some point in their lives, usually if they're tired or nervous; however, symptoms lasting longer than two months or recurring from time to time signal a deeper problem. Knowing what causes impotence is your first step in understanding and treating this condition.

Causes of Impotence in Men

According to the American Medical Association, several factors can cause erectile dysfunction—physical, psychological and emotional.

Physical Causes of Impotence

  • Alcohol, drug and tobacco use
  • Atherosclerosis (hardening of the arteries)
  • Diabetes (high blood sugar)
  • Fatigue
  • Heart disease
  • High cholesterol
  • Hypertension (high blood pressure)
  • Hypogonadism (which leads to lower testosterone levels)
  • Leaking veins in the penis
  • Liver or kidney failure
  • Multiple sclerosis
  • Neurological disorders (brain or spinal-cord injuries such as stroke, Alzheimer's, Parkinson's disease, multiple sclerosis)
  • Pelvic surgery or injury
  • Peyronie's disease (an inflammatory condition that causes scarring of the erectile tissue in the penis)
  • Prescription medications
  • Radiation therapy to the testicles
  • Some types of prostate or bladder surgery

Psychological and Emotional Causes of Impotence

Physical causes account for most instances of erectile dysfunction, however, there may also be psychological or emotional factors.

According to the University of Maryland Medical Center, psychological impotence usually develops rapidly and is likely related to a recent situation or event. One clue that you may have this type of erectile dysfunction is your ability to have or maintain an erection when you wake up in the morning. Common psychological or emotional causes of impotence are:

  • Anger
  • Anxiety
  • Depression
  • Grief
  • Guilt
  • Low self-esteem
  • Performance anxiety (fear of not being able to perform sexually)
  • Relationship problems
  • Stress
  • Tension
  • Worry

Main Causes of Impotence Can Be Prevented

"Erectile dysfunction is much more common in people who have cardiovascular risk factors," says Melvyn Rubenfire, a professor of internal medicine at the University of Michigan Health System. "The critical message is that erectile dysfunction may be a very early sign of atherosclerosis or a risk for heart attacks, strokes and other problems."

Since the risk factors for heart disease also can lead to the artery problems that cause erectile dysfunction, Rubenfire recommends that men take action to prevent both conditions with changes in diet and exercise.

"If you take a look at a population of men between 45 and 60, almost half of them may have erectile dysfunction. And if you look at those who have erectile dysfunction, lack of exercise, a high-fat diet and hypertension are all very common," says Rubenfire. "Prevention is the key."

To prevent impotence, especially if you're between 45 and 60, Rubenfire recommends practicing a healthy lifestyle that includes regular exercise, adequate rest, and good hygiene (including dental hygiene). He also suggests cutting fat in your diet, eating adequate amounts of fruits and vegetables, and receiving a regular health checkup.

Also, smoking is one of the main causes of impotence, so giving up cigarettes is essential if you want to prevent impotence. As Rubenfire explains, smokers have a much higher rate of erectile dysfunction because smoking impairs the function of the small vessels and the lining cells of the vessels that control erections.