Erectile dysfunction (ED) is a more specific term for impotence and is useful as it has fewer stigmas attached, and distinguishes ED from orgasmic and ejaculatory dysfunction (1 – 4). Impotence was defined as “the persistent inability to attain and maintain an erection adequate to permit satisfactory sexual performance” (5). This indicates that the erection is either too short lived or not firm enough for the man to penetrate his partner. In extreme cases, there may be no erectile response at all, this is termed “severe” or “complete” ED. Two large-scale studies have examined the prevalence and etiology of ED. In the late 1980s, Feldman’s team gathered complete information from 1290 men between the ages of 40 and 70 (6). Several of their characteristics were compared, including physical measures (e.g., height, serum cholesterol, etc.), medical conditions, medications, sociodemographics, race, and education. Erectile function was assessed using a nine-item sexual activity questionnaire. In the entire sample, the mean probability of some degree of impotence in this age group was 52.0 + 1.3%. In total, 17.2% had minimal ED, 25.2% had moderate ED, and 9.6% had complete ED. The severity of ED had some relation to increasing age even after adjusting for other factors; nevertheless, the other factors are of great importance. It was found that some diseases were strongly associated with changes in erectile function. Diabetes, heart disease, and hypertension, even when treated, were predictive of ED (after adjustment for age), and the pharmacological agents used in the treatment of these conditions seemed to relate to the group with no erectile response. Cigarette smoking was shown to be a strong risk factor for ED, especially amongst those who were still smokers at the time (56% complete impotence for current smokers compared with 21% for current nonsmokers). A Welsh study undertaken more recently has shown similar results but used a different methodology that was less discriminatory [e.g., it did not exclude men with no regular sexual partner (7)]. Both studies are weakened by the fact that .96% of the men were white, and therefore can only really reflect what is going on in their respective demographic areas.
It is all too easy to dismiss ED as a benign condition and therefore un- important. It should be realized that ED can cause a great deal of unnecessary suffering including low self-esteem and depression. ED often occurs together with relationship difficulties. Both the man and his partner may have a variety of issues that, if left unchecked, can adversely affect his family’s relationship dynamics. Other relationships outside the home may also be adversely affected. Because of the link between ED and depression (8) there is the probability of an economic impact as time off from work may be required. In addition to the psychological difficulties, there may be underlying pathology such as cardiovas- cular disease, diabetes, or hypertension. ED is sometimes the presenting factor in such chronic conditions (9).
There are many risk factors that cause or contribute to ED. Age is undoubtedly the greatest predictor of ED but ED is not necessarily a direct consequence of the aging process. It is simply that older men are more likely to have comorbidities. Shortness of breath, angina, pain (e.g., associated with arthritis), muscle weakness, and age associated disability can all contribute to the problem.
Other causes of ED can be classified as physical, psychological, or psychia- tric, with approximately two-thirds of men having a physical cause as the major contributing factor. The physical causes are mostly due to vascular or neurologi- cal damage, but the endocrine system can also be involved. Hypertension, hyper- lipidaemia, vascular disease, and diabetes can all alter the blood supply to the penis, and a problem with the venous system can cause leakage so that the erec- tion cannot be maintained. Diabetes, alcohol misuse, multiple sclerosis, spinal cord injury (SCI), and Parkinson’s disease are conditions in which neurological damage affects the transmission of erectogenic nerve signals from the brain. Altered testosterone and prolactin levels are of particular interest when exploring a hormonal cause. While thyroid function is not directly responsible for ED, it can affect sex drive, which may indirectly present as ED.
Substance misuse, schizophrenia, bipolar disorder, and personality dis- orders (e.g., obsessive-compulsive type) are all psychiatric risk factors for ED. Paraphilias, such as fetishism, may cause ED when the object of desire is absent. By far, the most common psychiatric cause of ED is depression. Inver- sely, depression is also a major consequence of ED, and it can be difficult to distinguish which occurred first (10). Ironically, some of the antidepressant treatments contribute to the long list of causative factors for ED (Table 7.1).
Table 7.1 Antidepressant Drugs Implicated as a Cause of Erectile Dysfunction
All tricyclics including Amitryptyline Clomipramine Imipramine
All mono-amine oxidase inhibitors including
Phenelzine Isocarboxazid Tranylcypramine
All selective serotonin re-uptake inhibitors
Other antidepressant drugs may NOT cause sexual dysfunction. These include: Mirtazapine
Flupentixol Nefadozone Reboxetine Tryptophan Venlafaxine
Source: Information from British National Formulary.
Whereas the organic causes of ED are most often associated with the older age group, psychological problems can be a primary cause of ED more often seen in younger men. The young man may present as being anxious about the reliability of his erections. He may need reassurance that few men are able to achieve an erection at will, in all situations, and at all times. Secondary psycho- logical problems may occur when the man loses the ability to enjoy satisfactory sexual activity due to a physical disorder. Anxiety, stress, loss of self-confidence and self-esteem are all common psychological problems that present in any clinic (11). Guilt about sexual thoughts or feelings, and negative cognitions may also result in ED. Although they act on physiological systems, erectogenic medi- cations may rectify a psychological problem by helping the individual to achieve an erection. In some cases it is enough for him to break out of a psycho- logical “vicious circle.” In other cases, the underlying psychology may remain, and the person may become reliant on the medication (and therefore the prescriber) to help him achieve an erection with his partner.
Other organic causes of ED include chronic conditions such as renal disease. Surgery (e.g., prostate surgery), trauma (particularly to the pelvic region), and structural abnormalities such as Peyronie’s disease are other factors that should be considered. Drugs, either prescribed or recreational, can be a source of ED. The most important groups of pharmacological agents to con- sider are antidepressants, the centrally acting antihypertensive drugs; central nervous system depressants; beta-adrenoceptor antagonists; and any drugs that have an anticholinergic action. A major factor that contributes both directly and indirectly to ED is smoking! Simply by giving up smoking, a man’s ability to achieve an erection can improve (4,12). Additionally, nicotine is a vasoconstric- tor when present in the blood. Unfortunately, the long term consequences of smoking, such as vascular disease, are not so easily rectified (12).