Causes of Impotence

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 ED causes. Underlying conditions associated with erectile dysfunction include the following:

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:

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 Imbalances

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, bladde, 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 percent 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.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 09 Jun 1998

Last Modified: 01 Dec 2011