Erectile dysfunction (ed), formerly called impotence, can affect men of all ages although it is much more common among older men. It is normal for healthy men of all ages to occasionally experience erectile dysfunction. However, if the problem becomes chronic, it can have adverse effects on relationships, emotional health, and self-esteem. Erectile dysfunction may also be a symptom of an underlying health condition. If erectile dysfunction becomes an on-going problem, it is important to talk to your doctor.
Causes of erectile dysfunction
Physical causes are the main reasons for erectile dysfunction. They include heart disease, high blood pressure, diabetes, neurological disease, medication side effects, and other health conditions.
Psychological causes of erectile dysfunction include anxiety, depression, stress, and problems in relationships.
Lifestyle factors that increase the risk for erectile dysfunction include smoking, alcohol use, and other substance abuse.
Erectile dysfunction (formerly called impotence) is the inability to achieve or maintain an erection sufficiently rigid for sexual intercourse. Sexual drive and the ability to have an orgasm are not necessarily affected. Because all men have erection problems from time to time, doctors diagnose erectile dysfunction if a man fails to maintain an erection satisfactory for intercourse on at least 25% of attempts.
Erectile dysfunction is not new in either medicine or human experience, but it is not easily or openly discussed. Cultural expectations of male sexuality inhibit many men from seeking help for a disorder that can usually benefit from medical treatment.
The penis and erectile function
The structure of the penis. The penis is composed of the following structures:
Two parallel columns of spongy tissue called the corpus cavernosa, or erectile bodies.
A central spongy chamber called the corpus spongiosum, which contains the urethra, the tube that carries urine from the bladder through the penis.
These structures are made up of erectile tissue. Erectile tissue is rich in tiny pools of blood vessels called cavernous sinuses. Each of these vessels is surrounded by smooth muscles and supported by elastic fibrous tissue composed of a protein called collagen.
Erectile function and nitric oxide. The penis is either flaccid or erect depending on the state of arousal. In the flaccid, or unerect, penis, the following normally occurs:
Small arteries leading to the cavernous sinuses contract, reducing the inflow of blood.
The smooth muscles regulating the many tiny blood vessels also stay contracted, limiting the amount of blood that can collect in the penis.
During arousal, the following occurs:
The man's central nervous system stimulates the release of a number of chemicals, including nitric oxide, which is essential for producing and maintaining an erection.
Nitric oxide stimulates the production of cyclic GMP, a chemical that relaxes the smooth muscles in the penis. This allows blood to flow into the tiny pool-like cavernous sinuses, flooding the penis.
This increased blood flow nearly doubles the diameter of the spongy chambers.
The veins surrounding the chambers are squeezed almost completely shut by this pressure.
The veins are unable to drain blood out of the penis and so the penis becomes rigid and erect.
After ejaculation or climax, cyclic GMP is broken down by an enzyme called phosphodiesterase-5 (pde5), causing the penis to become flaccid (unerect) again.
Important substances for erectile health
A proper balance of certain chemicals, gases, and other substances is critical for erectile health.
Collagen. The protein collagen is the major component in structural tissue in the body, including in the penis. Excessive amounts, however, form scar tissue, which can impair erectile function.
Oxygen. Oxygen-rich blood is one of the most important components for erectile health. Oxygen levels vary widely from reduced levels in the flaccid state to very high in the erect state. During sleep, a man can normally have three to five erections per night, bringing oxygen-rich blood to the penis. The primary cause of oxygen deprivation is ischemia -- the blockage of blood vessels. The same blood flow-reducing conditions that lead to heart disease, such as atherosclerosis, may also contribute to erectile dysfunction.
Testosterone and other hormones. Normal levels of hormones, especially testosterone, are essential for erectile function, though their exact role is not clear.
Over the past decades, the medical perspective on the causes of erectile dysfunction has shifted. Common belief used to attribute almost all cases of ed to psychological factors. Now doctors believe that up to 85% of ed cases are caused by medical or physical problems. Only 15% are completely psychologically based. Sometimes, erectile dysfunction is due to a combination of physical and psychological causes.
A number of medical conditions share a common problem with erectile dysfunction -- the impaired ability of blood vessels to open and allow normal blood flow.
Heart disease, atherosclerosis, and high blood pressure
Heart disease, atherosclerosis, high blood pressure, and high cholesterol levels are major risk factors for erectile dysfunction. In fact, erectile problems may be a warning sign of these conditions in men at risk for atherosclerosis. Men who experience ed have a greater risk for angina, heart attack, or stroke.
Erectile dysfunction is a very common problem in men with high blood pressure. Many of the drugs used to treat hypertension (such as calcium channel blockers and beta-blockers) may also cause ed.
Diabetes is a major risk factor for erectile dysfunction. Blood vessel and nerve damage are both common complications of diabetes. When the blood vessels or nerves of the penis are involved, erectile dysfunction can result. Diabetes is also associated with heart disease and chronic kidney disease, other risk factors for ed.
Obesity increases the risk for diabetes, heart disease, and erectile dysfunction.
Metabolic syndrome -- a cluster of conditions that includes obesity and abdominal fat, unhealthy cholesterol and triglyceride levels, high blood pressure, and insulin resistance -- is also a risk factor for erectile dysfunction in men older than 50 years.
Benign prostatic hyperplasia
Although benign prostatic hyperplasia (BPH or 'enlarged prostate') does not cause erectile dysfunction, surgical and drug treatments for the condition can increase the risk for erectile dysfunction.
Diseases that affect the central nervous system can cause erectile dysfunction. These conditions include Parkinson's disease, multiple sclerosis, and stroke.
Endocrinologic and hormonal conditions