Erectile Dysfunction

Important Facts

• Erectile dysfunction can have a physical or psychological cause
• Nerve damage and reduced blood flow are common physical causes
• Medications, neurological conditions, and trauma also can cause ED
• Psychological causes for ED include depression, anxiety, and stress

Overview

Erectile dysfunction (ED) is the inability of a man to achieve or maintain an erection sufficient for his sexual needs or the needs of his partner.Most men experience this at some point in their lives, usually by age 40, and are not psychologically affected by it.

Some men, however, experience chronic, complete erectile dysfunction (impotence), and others, partial or brief erections. Frequent erectile dysfunction can cause emotional and relationship problems, and often leads to diminished self-esteem. Erectile dysfunction has many causes, most of which are treatable, and is not an inevitable consequence of aging.

Incidence and Prevalence
The term "erectile dysfunction" can mean the inability to achieve erection, an inconsistent ability to do so, or the ability to achieve only brief erections. These various definitions make estimating the incidence of erectile dysfunction difficult. According to the National Institutes of Health in 2002, an estimated 15 million to 30 million men in the United States experience chronic erectile dysfunction.

According to the National Ambulatory Medical Care Survey (NAMCS), approximately 22 out of every 1000 men in the United States sought medical attention for ED in 1999.

Incidence of the disorder increases with age. Chronic ED affects about 5% of men in their 40s and 15–25% of men by the age of 65. Transient ED and inadequate erection affect as many as 50% of men between the ages of 40 and 70.

Diseases (e.g., diabetes, kidney disease, alcoholism, atherosclerosis) account for as many as 70% of chronic ED cases and psychological factors (e.g., stress, anxiety, depression) may account for 10–20% of cases. Between 35 and 50% of men with diabetes experience ED.

Causes

There are many underlying physical and psychological causes of erectile dysfunction. Reduced blood flow to the penis and nerve damage are the most common physical causes. Underlying conditions associated with erectile dysfunction include the following:

• Vascular disease
• Diabetes
• Drugs
• Hormone disorders
• Neurologic conditions
• Pelvic trauma, surgery, radiation therapy
• Peyronie's disease
• Venous leak
• Psychological conditions

Vascular Disease
Arteriosclerosis, the hardening and narrowing of the arteries, causes a reduction in blood flow throughout the body and can lead to impotence. It is associated with age and accounts for 50% to 60% of impotence in men over 60.

Risk factors for arteriosclerosis include:

• Diabetes mellitus
• High blood pressure
• High cholesterol

Smoking, which can lead to any of the above risk factors, is perhaps the most significant risk factor for impotence related to arteriosclerosis.

Diabetes Mellitus
Chronic high levels of blood sugar associated with diabetes mellitus often damage small blood vessels and nerves throughout the body, which can impair nerve impulses and blood flow necessary for erection. About 60% of men with diabetes experience impotence.

Drugs
Over 200 commonly prescribed drugs are known to cause or contribute to impotence, including drugs for high blood pressure, heart medications, antidepressants, tranquilizers, and sedatives. A number of over-the-counter medications also can lead to impotence. Long-term use of alcohol and illicit drugs may affect the vascular and nervous systems and are associated with erectile dysfunction.

Hormone Disorders
Hormone disorders account for fewer than 5% of cases of impotence. Testosterone deficiency, which occurs rarely, can result in a loss of libido (sexual desire) and loss of erection. Among other conditions, an excess of the hormone prolactin, caused by pituitary gland tumor, reduces levels of testosterone. Hormone imbalances can also result from kidney or liver disease.

Neurologic Conditions
Spinal cord and brain injuries (e.g., paraplegia, stroke) can cause impotence when they interrupt the transfer of nerve impulses from the brain to the penis. Other nerve disorders, such as multiple sclerosis (MS), Parkinson's disease, and Alzheimer's disease, may also result in impotence.

Pelvic Trauma, Surgery, Radiation Therapy
Trauma to the pelvic region or spinal cord can damage veins and nerves needed for erection. Surgery of the colon, prostate, bladder, or rectum may damage the nerves and blood vessels involved in erection. Prostate and bladder cancer surgery often require removing tissue and nerves surrounding a tumor, which increases the risk for impotence.

New nerve-sparing techniques aimed at lowering the incidence of impotence to 40% to 60% are now being developed and used in these surgeries. Temporary impotence is also associated with these procedures, even those in which nerve-sparing techniques were used. It can take as long as 6 to 18 months for full erections to return.

Radical cystectomy (for bladder cancer) and prostatectomy (for prostate cancer) require cutting or removing nerves that control penile blood flow. These nerves do not control sensation in the penis and are not responsible for orgasms; only erection is affected by these procedures.

Radiation therapy for prostate or bladder cancer also can permanently damage these nerves.

Peyronie's Disease
Peyronie's disease is a rare inflammatory condition that causes scarring of erectile tissue. Scarring produces curvature of the penis that can interfere with sexual function and cause painful erections.

Venous Leak
If the veins in the penis cannot prevent blood from leaving the penis during erection, erection cannot be maintained. Venous leak can be a result of injury, disease, or damage to the veins in the penis.

Psychological Conditions
Depression, guilt, worry, stress, and anxiety all contribute to loss of libido and erectile dysfunction. If a man experiences loss of erection, he may worry that it will happen again. This can produce anxiety associated with performance and may lead to chronic problems during sex. If the cycle is inescapable, it can result in impotence. Psychological factors in impotence are often secondary to physical causes, and they magnify their significance.