The main symptom is the inability to attain or maintain adequate erection to complete sexual activity.
As a result of this symptom, affected men may also experience depression and distress, and this symptom can cause interpersonal (including marital) issues.
Causes & Risk Factors
A precise determination of the cause of any individual case of ED is often difficult and may be impossible because ED is often due to multiple factors. This is a consequence of the complicated nature of the human sexual response and the complex physiology of penile erection and relaxation. Normal erectile function requires the coordination of vascular, neurologic, hormonal and psychological factors and any condition that interferes with one or more of these processes may result in ED.
Attitudes concerning age and psychological factors, commonly associated with ED in the past, have changed in the last two decades. Although the prevalence of ED increases with advancing age, ED is no longer regarded as an inevitable consequence of aging. Whereas most cases of ED were once considered primarily psychological and/or psychiatric in origin, it is now well-recognized that organic, non-psychological causes of ED play a much more significant role in the development of ED. Most researchers agree that pure psychological (emotional) mechanisms are causative in 15% to 20% of cases with organic causes responsible for at least 80% of ED cases. In a number of cases, the situation is “mixed,” with significant secondary psychological and social components such as guilt, depression, anxiety, tension or marital discord being present in addition to one or more underlying organic components.
Causes of ED may be grouped into those factors that arise within the individual (endogenous) and those factors arising from sources outside the body (exogenous). Endogenous factors include endocrine imbalances, cardiovascular and other medical conditions, and emotional causes. Included among exogenous factors are medications, surgery, trauma and irradiation, smoking, and alcohol and substance abuse. Many of these causes are discussed in more detail in the following list of causes:
- Diabetes mellitus. This is the single most common cause of ED by virtue of its combined nerve and blood vessel damage. At least 40% of male diabetics have ED.
- Circulation abnormalities. Vascular (circulation-related) causes include diseases of the aorta or the arteries supplying the pelvis and penis. Hardening of the arteries (arteriosclerosis) is the most common vascular cause, but damage to the arteries may result from trauma, surgery, or irradiation. Surgery involving the prostate gland may involve both the arteries and nerves in that region.
- Neurological causes, including diseases of the brain (such as Alzheimer’s disease) and spinal cord (multiple sclerosis, for example).
- Hormonal or endocrine causes. These are uncommon causes for ED, however. ED may occur in males with deficient testicular function and low circulating levels of the male sex hormone, testosterone. These cases are referred to as hypogonadism and may be due to congenital abnormalities or testicular disease such as that accompanying mumps.
- Penile diseases: Organic causes of ED may be related to diseases of the penis. Many factors influence penile circulation. For instance, Peyronie’s disease, a condition characterized by fibrous tissue and a downward bowing of the penis, limits the expandability of the penile tissues, thus preventing venous compression and allowing blood to leave the penis. Similarly, arteriosclerotic plaque, injury to blood vessels’ inner lining due to trauma, surgery, or irradiation, or even aortic occlusion (blockage in a main artery leading out of the heart) can be the cause of compromised penile blood flow and prevent penile erection.
- Medications: A number of classes of medications can cause ED. Not all agents within each drug class produce the same effects. For example, some antidepressants are associated with ED, whereas an antidepressant called trazodone hydrochloride (Desyrel) has been used in institutional studies for the treatment of ED because of its tendency to produce priapism. Some medication classes that can cause ED include (but are not limited to): medications that reduce high blood pressure, medications taken for central nervous system diseases like Parkinson’s disease (methyldopa), antidepressants, sedatives or tranquilizers like barbiturates, anti-anxiety medications like diazepam (Valium), common, non-prescribed drugs such as tobacco and alcohol, and drugs of abuse including heroin.
- Psychological factors that can precipitate ED include stress, fatigue, depression, guilt, low self-esteem and negative feelings for or by a sexual partner. Depressive symptoms and/or difficulty coping with anger may be particularly influential, and ED may be related to a “submissive personality.”
- Lifestyle: Obesity, physical inactivity, cigarette smoking, and excessive intake of alcohol are risk factors for the development of ED. These suggest that changes in lifestyle may constitute an important aspect of both the therapy and prevention of ED.
The identification of risk factors for ED has an important impact not only on the treatment, but on the prevention of ED as well. For example, if a doctor is treating a patient for high blood pressure who is also at risk for ED, the doctor may make an informed decision to prescribe an effective medication that is not associated with ED instead of one that is.
ED AS A MARKER FOR OTHER DISEASES. The frequent association between ED and a number of important vascular conditions such as hypertension and coronary artery heart disease has raised the possibility that ED may serve as an important marker for the detection of these vascular disorders. Additionally, an increased incidence of depression has been noted in men with ED that is believed to be distinct from the reactive type of depression that might occur because of ED. This has led to the recognition of a possible syndrome linking depression and ED. Thus, the presence of depression should be investigated in men presenting with ED.
The first step in the treatment of ED includes the elimination or alteration of modifiable risk factors or causes, such as lifestyle or psychosocial factors including smoking, obesity, substance and alcohol abuse, and the alteration of prescription and over-the-counter medications if necessary.
Recommended treatment options for ED include the following medications:
- Oral erectogenic medications
- PDE-5 inhibitors. Sildenafil (Viagra) is an example. It works by blocking PDE-5 thereby allowing cGMP to have a longer effect, increasing penile blood flow and producing erection.
- Alpha adrenergic blockers
Vacuum constriction device therapy, which involves a mechanical device to increase penile blood flow and erection may also be recommended. Psychosexual therapy is also recommended so that any psychological causes for ED can be detected and therapy can be instituted. Individual psychotherapy or couples therapy may be helpful. These various treatment methods can be used alone or in combination.
If those therapies are unsuccessful, the following treatment options may be recommended:
- Intracavernous therapy (ICIT). This therapy involves injection of the penile structures with substances that promote blood flow and produce erection.
- Intraurethral therapy. Medications are inserted into the urethra and act to increase blood flow and muscle relaxation, allowing for erection.
- Penile prostheses. These are various devices inserted surgically into the penis to produce the erect state.
- Surgery. In rare cases, surgery may be used to correct a defect that interferes with penile erection.
Regardless of the therapy chosen, follow-up at regular intervals and good communication between the patient and the doctor is essential. Patients need to keep their doctors informed about adverse reactions, and patients need to be informed about drug interactions. The doctor may adjust the dosage of medication, or may substitute or add a therapeutic agent into the treatment, as necessary.
The patient and his sexual partner can work with their treatment team so that they are both well-informed about various treatment options and can maximize treatment results.