What is erectile dysfunction?

Erectile dysfunction (ED), also known as impotence, is the inability to achieve or sustain an erection for satisfactory sexual activity. Erectile dysfunction is different from other conditions that interfere with male sexual intercourse, such as lack of sexual desire (decreased libido) and problems with ejaculation and orgasm (ejaculatory dysfunction). This article focuses on the evaluation and treatment of erectile dysfunction.

How common is erectile dysfunction?

Erectile dysfunction (ED, impotence) varies in severity; some men have a total inability to achieve an erection, others have an inconsistent ability to achieve an erection, and still others can sustain only brief erections. The variations in severity of erectile dysfunction make estimating its frequency difficult. Many men also are reluctant to discuss erectile dysfunction with their doctors due to embarrassment, and thus the condition is underdiagnosed. Nevertheless, experts have estimated that erectile dysfunction affects 30 million men in the United States.

While erectile dysfunction can occur at any age, it is uncommon among young men and more common in the elderly. By age 45, most men have experienced erectile dysfunction at least some of the time. According to the Massachusetts Male Aging Study, complete impotence increases from 5% among men 40 years of age to 15% among men 70 years and older. Population studies conducted in the Netherlands found that some degree of erectile dysfunction occurred in 20% of men between ages 50-54, and in 50% of men between ages 70-78. In 1999, the National Ambulatory Medical Care Survey counted 1,520,000 doctor-office visits for erectile dysfunction. Other studies have noted that approximately 35% of men 40-70 years of age suffer from moderate to severe ED, and an additional 15% may have milder forms.

What are some of the risk factors for erectile dysfunction?

The common risk factors for ED include the following:

  • Advanced age
  • Cardiovascular disease
  • Diabetes mellitus
  • High cholesterol
  • Cigarette smoking
  • Recreational drug use
  • Depression or other psychiatric diseases

What are the causes of erectile dysfunction?

The ability to achieve and sustain erections requires

  • a healthy nervous system that conducts nerve impulses in the brain, spinal column, and penis,
  • healthy arteries in and near the corpora cavernosa,
  • healthy smooth muscles and fibrous tissues within the corpora cavernosa,
  • adequate levels of nitric oxide in the penis.

Erectile dysfunction can occur if one or more of these requirements are not met. The following are causes of erectile dysfunction:

Aging: There are two reasons why older men are more likely to experience erectile dysfunction than younger men. First, older men are more likely to develop diseases (such as heart attacks, angina, cardiovascular disease, strokes, diabetes mellitus, and high blood pressure) that are associated with erectile dysfunction.
Diabetes mellitus: Erectile dysfunction tends to develop 10-15 years earlier in diabetic men than among nondiabetic men. In a population study of men with type I diabetes for more than 10 years, erectile dysfunction was reported by 55% of men 50-60 years of age.
Hypertension (high blood pressure): People with essential hypertension or arteriosclerosis have an increased risk of developing erectile dysfunction. Essential hypertension is the most common form of hypertension; it is called essential hypertension because it is not caused by another disease (for example, by kidney disease).
Cardiovascular diseases: The most common cause of cardiovascular diseases in the United States is atherosclerosis, the narrowing and hardening of arteries that reduces blood flow. Atherosclerosis typically affects arteries throughout the body and is aggravated by hypertension, high blood cholesterol levels, cigarette smoking, and diabetes mellitus.
Cigarette smoking: Cigarette smoking aggravates atherosclerosis and thereby increases the risk for erectile dysfunction.
Nerve or spinal cord damage: Damage to the spinal cord and nerves in the pelvis can cause erectile dysfunction. Nerve damage can be due to disease, trauma, or surgical procedures.
Low testosterone levels: Testosterone (the primary sex hormone in men) is not only necessary for sex drive (libido) but also is necessary to maintain nitric oxide levels in the penis. Therefore, men with hypogonadism (diminished function of the testes resulting in low testosterone production) can have low sex drive and erectile dysfunction.
Medications: Many common medicines produce erectile dysfunction as a side effect. Medicines that can cause erectile dysfunction include many used to treat high blood pressure, antihistamines, antidepressants, tranquilizers, and appetite suppressants.
Depression and anxiety: Psychological factors may be responsible for erectile dysfunction. These factors include stress, anxiety, guilt, depression, widower syndrome, low self-esteem, posttraumatic stress disorder, and fear of sexual failure (performance anxiety). It is also worth noting that many medications used for treatment of depression and other psychiatric disorders may cause erectile dysfunction or ejaculatory problems.