Ever since the ground-breaking work of Kinsey, the prevalence of erectile dysfunction has been a subject of debate. Although it is certain that many millions of men are affected by the condition, there is a surprising dearth of high-quality epidemiological data with which to quantify accurately the extent of the problem. A figure of one man in ten has often been quoted as an estimate of the prevalence of erectile dysfunction, but the frequency and severity of the disorder vary markedly with age. Erectile dysfunction is uncommon in young men (with the exception of intermittent psychogenic problems), becomes more common in middle age, and is highly prevalent in men more than 60 years of age. Thus, to some extent, erectile dysfunction is a natural expression of aging, but one that men are increasingly less willing to accept without seeking treatment. As the world’s population ages over the next few decades, the number of men who will suffer erectile dysfunction seems certain to rise.
One problem for epidemiologists trying to quantify the extent and impact of erectile dysfunction is the frequent unwillingness of men to discuss the problem frankly. The accuracy of almost all data in this disease area is therefore impaired by the reluctance of many, particularly older, men to respond to what they regard as overly personal questions. However, with the development of simple questionnaires which can be self-administered, and the gradual breakdown of social taboos surrounding the open discussion of sexual issues, it is possible to anticipate higher-quality information in the future.
At this time, however, the best data available concerning the prevalence of erectile dysfunction are derived from the Massachusetts Male Aging Study. The findings of this study may be summarized as follows. A total of 1290 men aged 40–70 years were included in the study; erectile dysfunction was very common,
- with 52% of men reporting some degree of erectile dysfunction—mild in 17.1%,
- moderate in 25.2%
- complete in 9.6%.
Complete erectile dysfunction was reported by 5% of men at 40 years of age, rising to 15% at age 70 years. Loss of firm erections is often extremely bothersome to men. demonstrates the degree of worry, the loss of confidence, the negative feelings and the depression that can result.
Risk factors for erectile dysfunction
Risk factors for organic erectile dysfunction mainly stem from the fact that the erectile mechanism is a vasodilatory response dependent on smooth muscle function under neurogenic control. Aging, which has the strongest association with erectile dysfunction, probably exerts its effects mainly through impaired vasodilatory and venoocclusive mechanisms. Atheroma of the internal iliac arteries and their pudendal branches may be one factor, but age-related degeneration of intracorporeal smooth muscle mechanisms is probably more important. Venous leakage, another age-related phenomenon, may in itself be a manifestation of deterioration of intracorporeal smooth muscle function.
DIABETES MELLITUS
This disease is an important risk factor for erectile dysfunction. Damage to small blood vessels is the main etiology and, therefore, erectile dysfunction often occurs in association with diabetic retinopathy. Diabetic peripheral autonomic neuropathy is a further contributory factor. Erectile dysfunction may develop as a result of the progressive loss of small unmyelinated socalled C fibers secondary to diabetes. Several groups have reported that diabetes is associated with loss of NO synthase from NANC nerve endings and endothelial cells in the corpora. This may explain the pathophysiological basis of the erectile dysfunction that so commonly accompanies diabetes.
HYPERTENSION
This is frequently associated with erectile dysfunction. Approximately one-third of men beyond middle age have a diastolic blood pressure >90 mmHg. Hypertension causes damage to small blood vessels and this may adversely affect intracorporeal vasodilatory mechanisms. Moreover, many of the agents used to control hypertension, especially β-blockers and diuretics, are associated with the development of erectile dysfunction. It has been postulated that, because high intracorporeal pressures are required to produce penile rigidity, the reduction of blood pressure by any agent is likely to increase the incidence of erectile dysfunction. However, α-blockers, perhaps through the induction of intracorporeal vasodilatation, appear to enhance erection, while still lowering both systolic and diastolic blood pressures.
HYPERLIPIDEMIA
This disease often occurs in association with hypertension and is also a cause of damage to the peripheral vascular system. Hypercholesterolemia and elevated serum triglyceride levels are both also associated with erectile dysfunction.
SMOKING
Although there have been few epidemiological studies to confirm this, it appears likely that heavy smoking is associated with erectile dysfunction because of its deleterious effects on blood vessels and its action leading to an increase of platelet stickiness.
PEYRONIE’S DISEASE
Fibrosis developing in the corpora albuginea may result in permanent scarring and consequent deformity of erection. When the fibrosis is severe, penetrative intercourse may be impossible. As a result of the loss of tunica elasticity, Peyronie’s disease may also be associated with venous leak-induced erectile dysfunction.
PREVIOUS SURGERY
Various forms of pelvic surgery, particularly radical prostatectomy, cystoprostatectomy and abdominoperineal resection, are all strongly associated with subsequent erectile dysfunction.
DEPRESSION
Reactive or endogenous depression is strongly associated with erectile dysfunction: nearly 90% of severely depressed men report complete impotence. Treatment with antidepressants may sometimes improve the situation, although both monoamine oxidase inhibitors and tricyclic antidepressants may in themselves cause erectile dysfunction. Selective serotonin reuptake inhibitors, such as fluoxetine (Prozac®) may not only cause erectile dysfunction, but may also retard ejaculation.