Erectile Dysfunction

Erectile Dysfunction

Not so long ago, erectile dysfunction (ED) was a problem that men seemed to accept as a natural, if frustrating, consequence of aging. Then in the spring of 1998, Viagra—the first oral medication to treat ED—hit the market, followed a few years later by Levitra and Cialis. Another ED drug, Stendra, was approved in 2012. The phenomenal response to these pharmaceutical solutions for ED has been dubbed a second sexual revolution, the first having occurred with the advent of birth control pills. Both types of medications fostered major changes in sexual behavior and the ways in which people think about and talk about sexuality.

What is erectile dysfunction?

Simply put, ED is trouble attaining and sustaining an erection sufficient for sexual intercourse. At least 25% of the time, the penis doesn’t get firm enough, or it gets firm but softens too soon.

Often, the problem develops gradually. One night it may take longer or require more stimulation to get an erection. Another time, an erection may not be as firm as usual, or it may end before orgasm. When such difficulties occur regularly, it’s time to talk to your doctor.

Causes of erectile dysfunction

Failing to have an erection one night after you’ve had several drinks—or even for a week or more during a time of intense emotional stress—is not ED. Nor is the inability to have another erection soon after an orgasm. Nearly every man occasionally has trouble getting an erection, and most partners understand that.

Often, the culprit behind ED is clogged arteries (atherosclerosis), which can affect not only the heart but also other parts of the body. In fact, in up to 30% of men who see their doctors about ED, the condition is the first hint that they have cardiovascular disease. Other possible causes of ED include medications and prostate surgery, as well as illnesses and accidents. Stress, relationship problems, or depression can also lead to ED.

Treatment of erectile dysfunction

Regardless of the cause of ED, this problem often can be effectively addressed. For some men, simply losing weight may help. Others may need medications. If these steps aren’t effective for you, a number of other options, including injections and vacuum devices, are available. Given the variety of options, the possibility of finding the right solution is now greater than ever before.

How common is erectile dysfunction?

The National Institutes of Health estimates that ED affects as many as 30 million American men—and worldwide, according to estimates, the number could reach more than 300 million by 2025. However, when it comes to ED statistics and research, the gold standard continues to be a large and detailed study called the Massachusetts Male Aging Study (MMAS). Over three separate data-collection periods during a 17-year span—1987–89, 1995–97, and 2002–04—researchers collected blood samples plus health and biographical data from approximately 1,700 men ages 40 to 70 living near Boston. The MMAS researchers found that about 43% of the men had some degree of ED.

How common is ed?

Technically, ED can strike any man old enough to have an erection, but it becomes increasingly common with age. According to the National Kidney and Urologic Diseases Information Clearinghouse, roughly 1% of men in their 40s, 17% of men in their 60s, and 48% of men 75 or older have what’s called complete ED (meaning they are never able to achieve an erection sufficient for intercourse).


Often erectile difficulties are the result of an illness that becomes more prevalent with age. Or it may reflect the treatment of such an illness—erectile difficulties are a potential side effect of many medications.

Still, this doesn’t mean that ED is something that a man simply has to live with as he gets older. It isn’t. Although testosterone, a male sex hormone that plays a role in sexual performance, tends to decline with age, it remains within normal limits in most men. And while other age-related factors can affect a man’s ability to have an erection—for example, tissues become less elastic and nerve communication slows—even these factors don’t explain many cases of ED.

Preventing erectile dysfunction

Lifestyle can have an impact on whether or not you get ED or how severe it is. Physical activity, weight loss, and good nutrition are all associated with lower rates of ED and lower severity of the problem. In part, that’s because these measures can vastly reduce your risk of atherosclerosis. They also help reduce chronic, low-grade inflammation and increase levels of the signaling molecule nitric oxide, which helps to relax blood vessels, thus improving blood flow to the penis.

If you’re a smoker, smoking cessation is another important lifestyle change. Data mined from the Massachusetts Male Aging Study found that smoking doubled the likelihood of experiencing progressive problems in having erections, and that quitting smoking can help reverse the effect. Other studies have backed up this finding.

Intriguing data from the Massachusetts study also suggest that there may be a natural ebb and flow to ED—that is, for some men, trouble with erections may last for a significant amount of time, and then partly or fully disappear without treatment. Whether this is true, and which men need treatment versus tincture of time, may be resolved through further long-term studies in other populations.

Either way, it’s clear that good sexual function is possible well into old age. Research bears out that the majority of healthy older couples can—and do—have an active sex life. In surveys, 50% to 80% of healthy couples over age 70 say they have sex regularly; half say they have intercourse once a week. And some men continue to have erections into their 80s and 90s.

How an erection occurs

Basically, an erection illustrates simple hydraulics. Blood fills chambers in the penis, causing it to swell and become firm. But getting to that stage requires extraordinary orchestration of body mechanisms. Blood vessels, nerves, hormones, and, of course, the psyche must work together. A hitch in any one of these elements can diminish the quality of an erection or prevent it from happening altogether.

Frequently, an erection starts in a man’s brain. A sight, a touch, a smell, or perhaps just a memory sparks intense activity in the hypothalamus, an area near the base of the brain. Electrical signals of sexual arousal travel from the brain down to the lower part of the spinal cord. Nerves in this area signal nerves in the pelvis, which tell arteries to let blood into the penis and cause an erection.

Directly stimulating the genitals can also prompt an erection, though different nerve pathways are involved. Here, sexual sensation is carried by the pudendal nerve, which runs from the penis to the sacral nerves in the lower spine. The sacral nerves then send messages that cause the arteries in the penis to admit blood. During sexual activity, both of these nerve pathways are involved in producing an erection.

Nerves talk to each other by releasing nitric oxide and other chemical messengers. These messengers boost the production of other important chemicals, including cyclic guanosine monophosphate, prostaglandins, and vasoactive intestinal polypeptide. These chemicals initiate the erection by relaxing the smooth muscle cells lining the tiny arteries that lead to the corpora cavernosa, a pair of flexible cylinders that run the length of the penis.

Anatomy of a penis
The penis is made up of three cylindrical bodies: the corpus spongiosum (spongy body)—which contains the urethra and includes the glans (head) of the penis—and two corpora cavernosa (erectile bodies), which extend from within the body out to the end of the penis to support an erection. Blood enters the corpora cavernosa through the central arteries.

As the arteries relax, the thousands of tiny caverns, or spaces, inside these cylinders fill with blood. Blood floods the penis through two central arteries, which run through the corpora cavernosa and branch off into smaller arteries. The amount of blood in the penis increases sixfold during an erection. The blood filling the corpora cavernosa compresses and then closes off the openings to the veins that normally drain blood away from the penis. In essence, the blood becomes trapped, maintaining the erection.

how a penis works
When a man is sexually stimulated, chemical signals from the brain cause the penile arteries to widen, allowing more blood to enter the erectile bodies known as the corpora cavernosa. The tissues swell with blood, causing an erection. At the same time, the blood-engorged tissues compress the veins, keeping blood in the penis and maintaining the erection.

How does testosterone come into play? Scientists aren’t completely sure. This male sex hormone is pumped out mainly by the testes and in small amounts by the adrenal glands; overall, levels decline with age. Current thinking is that testosterone stokes the engine of sex drive, helping to trigger and sustain an erection. Some estimates suggest one to two out of 10 men with ED also have hormonal abnormalities. Yet a man with virtually no testosterone may still be able to have an erection. And a large study of older men, published in The Journal of Urology, reported no connection between erectile function and levels of various sex hormones, with the exception of luteinizing hormone. So, despite all the talk about hormones and virility, doctors currently don’t know exactly what role sex hormones play in normal libido or the ability to have erections.

Obviously, an erection isn’t permanent. Some signal—usually an orgasm, but possibly a distraction, interruption, or even cold temperature—brings an erection to an end. This process, called detumescence, occurs when the chemical messengers that started and maintained the erection stop being produced, and other chemicals, such as the enzyme phosphodiesterase 5 (PDE5), destroy the remaining messengers. Blood seeps out of the passages in the corpora cavernosa. Once this happens, the veins in the penis begin to open up again and the blood drains out. The trickle becomes a gush, and the penis returns to its limp, or flaccid, state.

It’s usually difficult for a man to get another erection right away. The length of the interval between erections varies, depending on a man’s age, his health, and whether he is sexually active on a regular basis. A young, sexually active man in good health may be able to get an erection after just a few minutes, whereas a man in his 50s or older may have to wait 24 hours. One reason may be that nerve function slows with age.

Indeed, erections may work on a use-it-or-lose-it principle. Some research suggests that when the penis is flaccid for long periods of time—and therefore deprived of a lot of oxygen-rich blood—the low oxygen level causes some muscle cells to lose their flexibility and gradually change into something akin to scar tissue. This scar tissue seems to interfere with the penis’s ability to expand when it’s filled with blood.

Orgasm and ejaculation

Some men find that even though they have trouble with erections, they can still experience orgasm. That’s because erections and orgasms involve different muscles and nerves. Even if there is a breakdown along the paths to an erection, orgasm is usually still possible. By contrast, some men with normal erections can’t achieve orgasm.

The exact mechanism of orgasm is still somewhat mysterious. It’s believed to result from stimulation of the pudendal nerve. During sexual arousal, local nerves tell muscles in the testes and the prostate to contract. This propels semen forward. Nerve impulses also tighten muscles at the neck of the bladder in order to keep semen from backing up into the bladder channel and flowing out through the urethra. Doctors believe that the pressure of the semen buildup and the muscle contractions experienced during ejaculation stimulate the pudendal nerve, producing the pleasurable sensation of orgasm.

In some cases, men can have an orgasm without ejaculating. This can be a side effect of certain drugs, including the alpha blockers—such as doxazosin (Cardura) and terazosin (Hytrin)—that are used to treat benign prostatic hyperplasia and high blood pressure. The selective serotonin reuptake inhibitors (SSRIs) used to treat depression and other psychiatric conditions also can induce problems with ejaculation.

Talk to your doctor

If you’re a man struggling with ED, you will be glad to know that there have never been more options for treating it. The first step in most cases is simply bringing it up with your doctor—not that this is always easy to do. A study of men ages 50 and older who went to a urologist for other, unrelated problems found that 74% of those who later admitted to having ED were too embarrassed to discuss the problem with their physicians. As this report explains, though, ED is a health issue like any other—albeit a very personal one—and a frank discussion with your doctor is to your advantage.