Sooner or later, just about every sexually active man will experience an isolated episode (or episodes) of erectile dysfunction. A little too much alcohol, "opening night jitters" the first time with a new partner, or mere fatigue, and Old Reliable just fails to answer the call. It happens, and it may be embarrassing, but it's not great cause for alarm. However, for men who have consistent difficulty with their sexual performance, it's quite a different story.

Erectile dysfunction, as a treatable condition, is defined simply as the inability to achieve or sustain an erection adequate for sexual intercourse. The characteristics of ED, however, are varied. For some men, it may mean they are still able to achieve and sustain a partial erection. Some may not be able to maintain an erection in sexual situations but continue to experience normal erections at night while sleeping and morning erections upon waking. A man may be able to achieve and maintain a rock-hard erection for masturbation but be utterly flaccid when he attempts penetrating vaginal intercourse. For some, the problem is sporadic--here today, gone tomorrow, back in a week, gone again later. For others the dysfunction is absolute--no erections of any kind, at any time, period.

Physicians can use the patient's description of these varying characteristics to determine what's causing the problem. Is it physical? Is it psychological? Is it caused by some medication the patient is taking? For example: if a man's ED has come on gradually over a period of months or years, a physician would probably suspect the cause was physical. If, on the other hand, a man's ED comes on abruptly, it is more likely to be the result of psychological factors or, quite possibly, the unexpected side effect of a particular medication. Likewise, one might suspect relationship issues to be the core problem for the man who has no difficulty masturbating but can't complete intercourse with his regular partner. 

Epidemiology

No one knows for sure how many men in the U.S. have ED. Estimates range from 10 million to 30 million. Since ED is neither fatal nor reportable, just about the only means epidemiologists have of determining its prevalence is by conducting surveys, i.e., contacting a scientifically selected sample of men and asking them about their sex lives. But such surveys are inherently flawed because men are generally reluctant to disclose that they have a sexual problem. ED remains highly stigmatized, though perhaps more in the mind of those who have it than among the general population. It's still common, after all, to see the term impotence, with all its inappropriately negative connotations of weakness and failure, used in place of the properly descriptive term erectile dysfunction. 

The likelihood of developing ED increases as men get older. The Baltimore Longitudinal Aging Study reported that by age 55, up to 8% of men have some degree of ED. This research also suggests that up to 25% of men experience some ED by age 65; by age 75, the figure goes up to 55%; and by age 80, to 75% (Morley. Am J Med. 1986;80:897-905). More recently, the 1992 National Health and Social Life Survey reported that "trouble maintaining or achieving an erection" was reported by 7% of 18- to 29-year-olds; 9% of 30- to 39-year-olds; 11% of 40- to 49-year-olds; and 18% of 50- to 59-year-olds (Laumann et al. JAMA. 1999;281:537-544). As for an overall estimate, according to the Massachusetts Male Aging Study, conducted from 1987 to 1989, approximately 52% of all men between the ages of 40 and 70 years have some degree of erectile dysfunction (Feldman et al. J Urol. 1994;151:54-61).

An important point to bear in mind here is that while the likelihood of ED increases as a man grows older, ED itself is in no way a natural consequence of aging. No man with ED, regardless of his age, need accept it "lying down," so to speak. Nor can any man be regarded as too old for ED therapy simply on the basis of age. You're never too old to rock 'n' roll.

Other risk factors

Besides aging, risk factors for ED include the following: diabetes, cardiovascular disease, spinal cord injury, cigarette smoking, depression, atherosclerosis, high blood pressure, pelvic surgery or trauma, arthritis, peripheral vascular disease, kidney failure, substance abuse (including alcohol), endocrine abnormalities, and ulcers. A quick look at this list tells us that ED can be associated with a number of serious conditions that may themselves need medical attention. This fact alone is a pretty compelling reason for men with untreated ED to overcome their shyness or reluctance and talk to a doctor. Curing or at least managing an underlying pathology may lead to the resolution of the ED without further drug therapy.
Another important risk factor for ED is the use of certain drugs, especially certain antidepressants, tranquilizers, hormones, and recreational drugs (including marijuana and alcohol). The list of prescription drugs known to be associated with ED includes, but is not limited to, the following: beta-blockers, thiazide, verapamil, naproxen, amytriptyline, digoxin, phenytoin, hydrazaline, clofibrate, indomethacin, cimetidine, omeprazole, metoclopramide, famotidine, and lithium. A physician conducting a thorough work-up of an ED patient will need a complete accounting of the patient's medication "history," including self-medication with recreational drugs, as an aid to differential diagnosis.
 
Differential diagnosis: finding the cause (or causes)
Physicians recognize five general etiologies or causes of ED: psychogenic, in which ED is mainly or entirely due to psychological factors or interpersonal problems; hormonal, wherein the root cause is testosterone deficiency; neurologic, indicating a problem with nerve function; vasculogenic, in which the problem arises from obstructed or otherwise deficient blood supply to the penis; and iatrogenic, meaning the ED occurs as a side effect of drug therapy.

Twenty years ago physicians believed ED was more-or-less "all in your head" and routinely referred their patients to psychiatrists and psychologists for treatment. Today it is well established that at least 70% of cases are due mainly to physical causes; however, it is often the case that ED will be of mixed etiology, meaning that more than one causative factor is at work. For example: by the time most men get around to seeing their doctor about ED, the stress of living with the problem and its impact on their interpersonal relationships will have induced a psychogenic component. Past failure to perform sexually can induce a "crippling" anxiety over present and future performance, creating a sort of feedback loop in which the problem compounds itself.

Therapy with a phosphodiesterase-5 (PDE-5) inhibitor such as Pfizer's sildenafil (Viagra) or Bayer's soon-to-be released vardenafil can, for many men, successfully treat ED regardless of its cause or causes, but a comprehensive work-up by a conscientious physician will include a differential diagnosis. Just because specific therapy for ED can restore sexual function doesn't mean it's always indicated; it may be more in the patient's best interest to treat an underlying pathology that is causing the dysfunction. A number of alternative treatments, including some non-drug options, are also available for those men who need specific therapy but are poor candidates for PDE-5 inhibitors.
Urology is the medical specialty best qualified to offer thorough, quality care for ED.

Conclusion