Erectile Dysfunction Introduction

Erectile dysfunction, sometimes called "impotence," is the repeated inability to get or keep an erection firm enough for sexual intercourse. The word "impotence" may also be used to describe other problems that interfere with sexual intercourse and reproduction, such as lack of sexual desire and problems with ejaculation or orgasm. Using the term erectile dysfunction makes it clear that those other problems are not involved.

Erectile dysfunction, or ED, can be a total inability to achieve erection, an inconsistent ability to do so, or a tendency to sustain only brief erections. These variations make defining erectile dysfunction and estimating its incidence difficult. Estimates range from 15 million to 30 million, depending on the definition used. According to the National Ambulatory Medical Care Survey (NAMCS), for every 1,000 men in the United States, 7.7 physician office visits were made for erectile dysfunction  in 1985. By 1999, that rate had nearly tripled to 22.3. The increase happened gradually, presumably as treatments such as vacuum devices and injectable drugs became more widely available and discussing erectile function became accepted. Perhaps the most publicized advance was the introduction of the oral drug sildenafil citrate (Viagra) in March 1998. NAMCS data on new drugs show an estimated 2.6 million mentions of Viagra at physician office visits in 1999, and one-third of those mentions occurred during visits for a diagnosis other than erectile dysfunction.

In older men, erectile dysfunction usually has a physical cause, such as disease, injury, or side effects of drugs. Any disorder that causes injury to the nerves or impairs blood flow in the penis has the potential to cause erectile dysfunction. Incidence increases with age: About 5 percent of 40-year-old men and between 15 and 25 percent of 65-year-old men experience erectile dysfunction. But it is not an inevitable part of aging.

Erectile dysfunction is treatable at any age, and awareness of this fact has been growing. More men have been seeking help and returning to normal sexual activity because of improved, successful treatments for erectile dysfunction. Urologists, who specialize in problems of the urinary tract, have traditionally treated erectile dysfunction; however, urologists accounted for only 25 percent of Viagra mentions in 1999.

What Causes Erectile Dysfunction?
Since an erection requires a precise sequence of events, erectile dysfunction can occur when any of the events is disrupted. The sequence includes nerve impulses in the brain, spinal column, and area around the penis, and response in muscles, fibrous tissues, veins, and arteries in and near the corpora cavernosa.

Damage to nerves, arteries, smooth muscles, and fibrous tissues, often as a result of disease, is the most common cause of erectile dysfunction. Diseases--such as diabetes, kidney disease, chronic alcoholism, multiple sclerosis, atherosclerosis, vascular disease, and neurologic disease--account for about 70 percent of erectile dysfunction cases. Between 35 and 50 percent of men with diabetes experience erectile dysfunction.

Also, surgery (especially radical prostate surgery for cancer) can injure nerves and arteries near the penis, causing erectile dysfunction. Injury to the penis, spinal cord, prostate, bladder, and pelvis can lead to erectile dysfunction by harming nerves, smooth muscles, arteries, and fibrous tissues of the corpora cavernosa.

In addition, many common medicines--blood pressure drugs, antihistamines, antidepressants, tranquilizers, appetite suppressants, and cimetidine (an ulcer drug)--can produce erectile dysfunction as a side effect.

Experts believe that psychological factors such as stress, anxiety, guilt, depression, low self-esteem, and fear of sexual failure cause 10 to 20 percent of erectile dysfunction cases. Men with a physical cause for erectile dysfunction frequently experience the same sort of psychological reactions (stress, anxiety, guilt, depression).

Other possible causes are smoking, which affects blood flow in veins and arteries, and hormonal abnormalities, such as not enough testosterone.

Advances in suppositories, injectable medications, implants, and vacuum devices have expanded the options for men seeking treatment for erectile dysfunction. These advances have also helped increase the number of men seeking treatment. Gene therapy for erectile dysfunction is now being tested in several centers and may offer a long-lasting therapeutic approach for erectile dysfunction.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) sponsors programs aimed at understanding the causes of erectile dysfunction and finding treatments to reverse its effects. NIDDK's Division of Kidney, Urologic, and Hematologic Diseases supported the researchers who developed Viagra and continue to support basic research into the mechanisms of erection and the diseases that impair normal function at the cellular and molecular levels, including diabetes and high blood pressure.

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