1 Causes of erectile dysfunction
2 Age-related ED
2.1 Men over 50
3 Erection problems in men aged between 20 and 40
3.1 Cardiovascular problems
3.1.1 ED and CVD
3.1.2 Cavernous arterial insufficiency
3.1.3 Smoking
3.2 Diabetes mellitus
3.3 Metabolic syndrome and erectile dysfunction
3.3.1 Recent research
3.4 Neurogenic factors
3.4.1 Sacral sex centre
3.5 Hypertension-induced ED
3.6 Hormone-induced ED
3.6.1 Testosterone level-induced ED
3.7 Surgical treatment
3.7.1 Radical prostatectomy
3.8 Physical injuries
3.9 Obesity and smoking
3.9.1 Smoking
3.10 Lower urinary tract disorder
3.10.1 Hypertension
3.11 Other findings

Causes of erectile dysfunction

Erectile dysfunction (also referred to hereinafter in an abbreviated form as “ED”) can occur due to a variety of factors. The most common causes can be categorised into four major groups:

⦁ Arterial diseases that prevent the vascular system from supplying enough blood to the penis. These are reported to be the one of the main somatic causes of ED, that being the case with some 40% of patients suffering from this condition.
⦁ Neurological disorder, which affects the nerves in one’s penis, preventing the normal synthesis of neural transmitters responsible for controlling the penile blood vessels and decreasing the overall sensitivity of the penis. This disrupts the normal erection process.
⦁ Penile vein abnormalities, which discontinue erection by drawing blood away from the penis, which thus cannot remain erected for a proper time. This may be caused by improper relaxation of vascular sinuses, abnormalities of the tunica or corporal muscle fibrosis.
⦁ Disruption of the arteriogenic system, which prevents the corpus spongiosum from expanding and being filled up with the required volume of blood.

Erectile dysfunction can also be caused by other medical conditions. One of the more prominent studies of the issue has revealed the following statistics:
⦁ the most prevalent cause (in 90% of patients taking part in the study) was psychological impotence stemming from depression; this is the main cause of ⦁ erectile dysfunction in men aged between 20 and 40
⦁ 86% had diseases of peripheral blood vessels
⦁ 64% suffered from diabetes mellitus
⦁ 61% had the coronary heart disease
⦁ 55% reported urinary tract symptoms
⦁ 52% had hypertension

Age-related ED

It is a commonly held percept that the prevalence and severity of erectile dysfunction is directly associated with one’s age. Apart from overall ageing of the body, the condition is most often aggravated further by a number of conditions, known to develop with age, including diabetes mellitus, CVD, hypertension, low testosterone levels and/or high cholesterol levels, infectious diseases affecting the urinary tract, chronic diseases impacting the neural system (Alzheimer, Parkinson, stroke, etc.) and probably the most pressing issue of today – psychological causes (depression, anxiety and other factors of the kind). Erectile dysfunction can in fact be caused by any of the aforementioned conditions, a combination thereof and/or the aggravation resulting from the respective therapy. Apart from that, 48% of male audience aged above 50 had erectile dysfunction induced by physical and relational circumstances. In the meantime, this does not imply that erection problems are inevitable with age.

Men over 50

At an age beyond 50, most men do actually retain their desire and interest in sex. In this age group, erectile dysfunction is often caused by atherosclerosis of the cavernosal and pudendal arteries. As with any other blood vessels, this means that the lumen of an artery is obstructed by plaques, impeding the blood flow to a certain extent. Common causes of atherosclerosis include increased cholesterol levels, hypertension, diabetes mellitus and, to an extent, smoking. The possible pathological effects developing due to the influence of these factors may include degradation of the smooth muscle in one’s penis, affecting the expansion capabilities of the cavernous body and causing venous leakage as a result.

Another risk factor associated with age and confirmed by a number of studies is the prostate. Men beyond the age of 50 often develop a disease called “benign prostate hyperplasia”, which can be the reason for erectile dysfunction, complicated or painful ejaculation and reduced sexual drive. These symptoms can sometimes be countered with alpha-blockers and ED drugs, such as Viagra, Cialis, etc. Typical prostatic disorder symptoms can include painful sensations in the respective areas of the body: pelvis, scrotum, perineum, lower abdomen, back, the suprapubic area and the inguinal area. Benign prostate hyperplasia can also manifest itself through the urgency and frequency of urination. A typical symptom would be unusually slow urination or burning sensation in the process. Being a complicated process, ageing can also cause other physiological phenomena that can be mistaken for sexual disorder symptoms, while, in essence, these are normal age-related changes. What matters most in these instances is proper knowledge and comprehension of these phenomena by the man and his partner/-s and respective adjustment of their sexual habits.

Erection problems in men aged between 20 and 40

Hardly ever expected to occur in men in their 20s/30s, erection problems can still be caused at this age by the omnipresent psychological stresses: depression, anxiety, etc. This is where pharmaceutical ED treatments such as Cenforce (Sildenafil) or Eli (Tadalafil) are especially useful, as these give a man a chance to regain confidence. When the situation is back to normal, this man can discontinue the use of medications and go on with his normal sexual life.

Cardiovascular problems

Advanced hardening, narrowing and clogging of blood vessels can be a major factor causing sexual dysfunction. This applies not just to the penile arteries, but to sinuses, iliac vessels, the aorta and tributaries as well. Amounting to about 40% of all factors, vascular diseases are yet another common cause of erectile dysfunction in man aged between 30 and 40. A common condition in men suffering from erectile dysfunction (17%) is atherosclerosis, the clogging of arteries with plaques that contain fatty substances, cholesterol and fat-absorbing cells known as lipophages. Excessive quantities of such plaques can obstruct or block a blood vessel altogether. Atherosclerosis is one of the so-called lifestyle diseases, as it is conduced by smoking and increased lipid blood levels, in particular, too much low density cholesterol and triglycerides. Other causes include obesity and diabetes mellitus. Erection thus deteriorates along with the blood flow in the penile area. Contracted vascular sinuses impede the compression of venules against the tunica, which causes venous leakage, making it hard for a person to maintain an erection.

ED and CVD

Erectile dysfunction can be directly associated with cardiovascular diseases. Erectile dysfunction could be an indirect indication of a cardiac condition, such as ischemic heart disease, which has not manifested itself in a more prominent way yet. It can occur months or even years before further, more sinister symptoms. This is why doctors often refer ED patients to cardiovascular examination in addition to the actual treatment. In this regard, we may remember an elegant idea of comparing the penis to a barometer of a kind, one that reflects the condition of one’s vascular system to an extent. Such concerns are especially relevant when dealing with factors like obesity, diabetes mellitus, increased blood lipids and smoking, as these are conducive to both ED and cardiac disorder. Patients with a single blood vessel obstructed due to ischemic heart disease usually have an easier time achieving an erection than those with multiple affected vessels.

Cavernous arterial insufficiency

Cavernous arterial insufficiency poses a high risk of coronary arterial disease. Being a complex condition, atherosclerosis has a number of other associated factors. At the enzymatic level, we might mention endothelial nitric oxide synthase, an enzyme that synthesises nitric oxide by processing oxygen and L-arginine when a person is sexually aroused, as well as excessive free radical levels and abundance of homocysteine at the vascular plaques. Erectile dysfunction can depend on any of these factors or any combination thereof. Profound studies of late reveal the shortage of nitric oxide synthase in the nitrergic nerves as yet another possible reason of sexual dysfunction. Other ED-related cardiovascular diseases include, without limitation, congestive heart failure and aortic aneurysm. A dedicated study of extragenital vascular disease involving a total of 457 patients with erectile problems has identified penile artery insufficiency in roughly 25% of the population of the study, and 75% of the affected ones also had penile, carotid or lower extremity atherosclerosis. This is yet another evidence of the interrelation between vascular changes in the body in general and penile arteries in particular. Another recent study based in Italy, however, identified age, diabetes, and coronary arteries as independent factors of erectile dysfunction. The findings thereof associated the condition with coronary arterial disease instead. Apart from that, ED has been reported in patients with acute coronary syndromes and presumed to be a symptom of diffused / coronary atherosclerosis.


Another study identified smoking as one of the three most common factors causing ED, the other two being obesity and hypertension. Men suffering from erectile dysfunction also had symptoms of arterial insufficiency, poor blood flow and coronary arterial disease, making about 40% of the group. Diabetes was reported in 23.3% of these men. Venous occlusive disease was also reported in the setting of hypertension in 36.5% of the group. Probability of blood flow parameter disorder increased along with the quantity of vascular disease risk factors present.

Diabetes mellitus

The prevalence of erectile dysfunction in patients with diabetes, according to different studies, is 30 to 75%. In turn, other studies reported approximately 1 of every 4 men with erectile dysfunction as having diabetes. Some results place erectile disorder among the first symptoms of diabetes. A study involving a number of patients with diabetes mellitus also showed that about 50% reported ED within 10 years of the initial DM diagnosis. Sexual dysfunction in patients with diabetes mellitus is also deemed dependent on the age of a specific patent. ED prevalence ranges from about 15% in men aged between 30 and 34 to 55% in the age group of 60 and above. At the same time, diabetes of type 2, prevalent across the older population group and associated with insulin resistance has been identified as causing erectile dysfunction more often than type 1 diabetes. Unique results have been produced by a recent study, which involved 401 men with erectile dysfunction without treatment being observed for a period of 9-15 years. The condition progressed in about 33% of men with ED rated as moderate to minimal, while the full recovery percentage was 32% for men with minimal symptoms, 14% for the moderate symptom group and 31% of men with complete erectile dysfunction. Remission of erectile dysfunction and impeded progression thereof were mostly conditional upon weight loss, smoking cessation and overall health improvement.

Metabolic syndrome and erectile dysfunction

According to expert findings of the National Institute of Health of 2001, the following clinical findings are indicative of metabolic syndrome:

⦁ Triglyceride levels over 150 mg/dL
⦁ Systolic blood pressure over 130 mmHg and diastolic blood pressure over 85 mmHg, or usage of antihypertensive medications.
⦁ HDL cholesterol levels below 40 mg/dL, or usage of lipid lowering medications.
⦁ Waist circumference of more than 40 inches / 100 centimetres.
⦁ Self-reported diabetes

Expert findings define metabolic syndrome as a precursor of cardiovascular diseases. Apart from that, it was found that about 43% of them had erectile dysfunction, as compared to just 24% of those with increased insulin resistance. Younger men complaining of erectile dysfunction but displaying no other clinical symptoms can be examined to detect potential metabolic syndrome at an earlier stage, which can reduce their risk of CVD and endothelial dysfunction at an older age.

Recent studies

Results of a recent study reinforce these findings, having shown that erectile dysfunction can anticipate the manifestation of metabolic syndrome among men with a body mass index of less than 25. This is an important finding, which recognises ED as an early diagnostics opportunity that allows timely intervention. It is especially valuable for men of older age with erectile dysfunction caused by low body mass index, as they run a higher risk of developing metabolic syndrome and other cardiovascular diseases that may stem therefrom.

Neurogenic factors

According to different observations, about 10 to 20% cases of erectile dysfunction were caused primarily by neurologic conditions. Disorders within the extremely complex nervous system can influence the sex-related portions of the brain, as well as other parts and organs: hypothalamus, the spinal cord pituitary gland and peripheral nerves. All these contribute to the overall sexual function of the body. An example would be a brain lesion, which, apart from other dire consequences, can affect the synthesis of vital neurotransmitters oxytocin and dopamine and inhibit the transmission of neural impulses from the sex centres of the brain to the nerves of the penile area through the spine. Alzheimer’s disease, Parkinson’s multiple sclerosis, injuries, infections, stroke, epilepsy and tumour can all cause such lesions. Psychogenic and reflexogenic aspects of erection can be disrupted by lesions on the spinal cord resulting from tumours, injuries, infections, diabetic neuropathy, disc hernia, multiple sclerosis or neurosyphilis. The resulting neural feedback disorder can also cause inability to experience pleasure from sex and render orgasm and ejaculation impossible. All these types of disorder interfere with the transmission of sensory impulses from the penis to the brain and the motor stimuli transmitted in the opposite direction.

Sacral sex centre

Severity of the condition depends largely on the extent and level of the underlying lesion, especially if it affects the secondary sex centre in the sacral region of the spine. Pathological affliction of the sacral sex centre can disrupt both psychogenic and reflexogenic erections. Loss of sensitivity and the subsequent erectile dysfunction can also be caused by injuries of nerves in the penile and pelvic areas that disrupt the travel of neural impulses to and from the penis. Spinal cord injuries resulting in quadriplegia and paraplegia do still allow sexual activity for about 70%, and about 70% of them use alternative forms of sexual expression, e.g. genital and oral stimulation. Another study has found that spinal injuries right above the sacral vertebrae still allow about 95% of this patient population to have reflexogenic erections. Around 25% men with partial sacral injuries retain the ability to maintain psychogenic erections. Incomplete lesions do affect erectile potential to a considerable extent: while most patients of this group can have an erection, it is brief and unpredictable, resulting in unsatisfactory ejaculation and hampered sexual function.

Hypertension-induced ED

Recent epidemiologic studies have confirmed that there is an association between the causes of erectile dysfunction and hypertension. Previous studies found that the share of patients with untreated hypertension who also reported erectile dysfunction upon their first increased blood pressure diagnosis was 8 to 10 percent. More recent studies, however, revealed a considerably higher prevalence within the range of 26% to 41%. Proliferation and size of the smooth muscles can be compromised due to adverse changes in the tissues at the corpora cavernosa, caused by hypertension-induced damage to the vascular epithelium of the penile arteries. Other consequences include hyperactivation of the nervous system and an increase in the inelastic fibrosis and collagen. Apart from that, this condition is potentially detrimental to the ability of penile blood vessels to dilate and relax, which is required for ensuring blood flow and, respectively, necessary for erection.

Furthermore, findings report low serum testosterone levels in some ED-afflicted men of younger age. This could impede the secretion of nitric oxide and make the tissue less responsive to the action thereof, potentially contributing to the psychological aspect of one’s sexual dysfunction due to anxiety. Another concern is that some of the medications used to treat hypertension can aggravate the patient’s sexual problems. Some of these drugs act as beta-blockers, which are known to lower one’s libido, causing erectile dysfunction. Commonly, this happens due to drug-induced constriction of the penile arteries. The anti-androgenic effect inherent in some drugs can also hamper one’s sexual desire, which is also detrimental to the quality of erection.

Hormone-induced ED

The “male hormone” testosterone is known to influence the development of male reproductive system and secondary sexual characteristics. Apart from being vital for the ability to experience sexual arousal, testosterone (its bioavailable serum form in particular) is also required to ensure proper functioning of male reproductive organs. The importance of testosterone is not restricted to the sexual organs alone, as it helps regulate the neurotransmitter secretions within the brain and the spinal cord. In spite of these considerations, the correlation between testosterone levels and erectile dysfunction is still being discussed. There is clinical and experimental evidence supporting the thesis that a man has to have a sufficient testosterone level in order to maintain normal sexual functioning. A recent clinical study of overall testosterone levels in male subjects reports that about 5% patients with erectile dysfunction have low hormonal levels, while low levels of free testosterone are reported in around 18%.

Testosterone supposedly facilitates erection by dilating the vascular sinuses and penile arterioles. Nevertheless, its effect on erectile dysfunction is still being debated on. About 6% of ED cases might be attributed to elevated serum levels of a pituitary hormone prolactin, which is often due to low testosterone. Effect of sex hormones on erectile dysfunction was researched within the boundaries of the Massachusetts Male Aging Study, which found that about 40 to 70% of the 1519 involved males were actually at the baseline level. No link was identified within the boundaries thereof between erectile dysfunction in men aged 20-30 and factors like bioavailable testosterone, total testosterone and the serum hormone-binding globulin. In some cases, however, researchers did point out that low serum testosterone levels resulted in reduced sexual drive.

Testosterone level-induced ED

Men with insufficient free testosterone would usually make use of hormone supplementation to boost their sexual activity to a normal level. Intramuscular testosterone injections, however, can cause an adverse response in older men with ED problems and low testosterone levels. The problem is that the injected hormone binds with blood proteins and decreases the free portion, resulting in a rapid increase in serum testosterone within just 72 hours, which then decreases gradually over the next 2-3 weeks. Several means exist today that can restore serum testosterone to the normal level within just 24-72 hours, such as gel, patches or peroral drugs. Testosterone injections can sometimes restore one’s erectile ability, even in men who have lost their testicles before reaching puberty. Though some castrated men are able to achieve and maintain occasional erections without testosterone supplementation therapy, this is not the case with most of them. Thyroid hormones, a vital component of a normal hormonal environment, may also be important for overall sexual functioning. Erectile dysfunction and reduced sexual drive can also be caused, apart from other things, by excessive (hyperthyroidism) or insufficient production of hormones by the thyroid gland.


Sexual dysfunction can be caused in both male and female patients by surgery on the pelvis, rectum or internal genitalia. This depends on the exact type of surgery a patient undergoes in each particular case. Bilateral orchiectomy, for instance, is most often a cause of erectile dysfunction, as it requires testicles to be removed for the treatment of prostate cancer and thus lowers the testosterone level in the castrated subject. Sexual dysfunction can also be caused by injury or loss of blood vessels or nerves participating in the erectile process, for example, those in the retroperitoneal area, right under the abdominal cavity. Other such surgical procedures creating the risk of erectile dysfunction are the extirpation of an abdominal aneurysm, which refers to the abnormal lump at the arterial wall, or surgery performed on the spinal cord. Radical prostatectomy, i.e. the removal of the cancerous prostate, also causes erectile dysfunction. Other surgical manipulations, for instance, simple prostatectomy procedure for benign prostatic hyperplasia, surgery of neurogenic bladder and radical surgery for rectal cancer can also be conducive to the development of erectile dysfunction and other sexual conditions.

Radical prostatectomy

The probability of postoperative ED after radical prostatectomy ranges between 20% and 100%, depending on one’s age and erectile capabilities before the surgery. Chances can be improved by surgical preservation of the nerve that triggers the supply of blood into the penis and the overall experience of the surgeon. Apart from that, some patients can develop incontinence upon reaching orgasm, which causes embarrassment and reluctance to engage in any type of sexual activity. Returning one’s erectile capabilities back to normal after radical prostatectomy may be affected by certain ED drugs like Cialis, Viagra and Levitra. Another option is the use of prostaglandin El injections, intra-urethral inserts or a combination of these methods. From the psychological point of view, inadequate desire or interest in sex of the patient’s sexual partner can trigger psychogenic disturbances, including depression. The overall erectile recovery rate in patients who have undergone bilateral surgery was between 32% and 80%, according to the follow-up of these patients for 2 to 4 years after the surgery.

Physical injuries

Erectile dysfunction can be caused or aggravated by physical trauma of the pelvic or penile nerves, caused by a traffic accident, ballistic wound, fall or pelvic fracture. Blood flow disruption in the penile vessels can also be a consequence of a trauma suffered at the adolescent age. Such injuries result, for example, from a bad bicycle crash, when the crotch is hit by the bike’s crossbar.

Obesity and smoking

Erectile dysfunction is often associated with obesity due to low physical activity, excessive eating and sedentary lifestyle, as well as smoking. Healthy balanced diet, regular exercise and withdrawal from smoking are enough to ensure recovery in about 30% of the cases. According to the respective study, loss of weight is a beneficial factor for restoring one’s sexual function even with no additional therapy. Elevated serum cholesterol levels have been found in 26% ED patients. With the concomitant diagnosis of hypertension, however, this percentage rises to 40-80. It is yet unknown how exactly the higher serum levels contribute to the deterioration of one’s sexual function. The few theories that exist in this regard are based on experiments performed on rats and rabbits. Most theories accentuate poor endothelium-dependent relaxation of the vascular bed, accumulation of low-density lipids in plaques, clogging of the penile arteries and higher concentration of the smooth muscle cells. Other factors include neurologic and vascular changes on atrophy and the decrease in the size and number of axons, degeneration of cavernosal smooth cells, as well as the loss of the growth factor of the vascular endothelial.


A direct relationship has been identified between the duration of smoking and the number of cigarettes that the patient smokes and erectile dysfunction, its development and severity. Deficiency of endothelium-dependent muscle relaxation in the penile vasculature is yet another factor contributing to erectile dysfunction. Poor rigidity in the event of nocturnal erections and the narrowing of pudendal arteries are also among the possible factors. Smokers also have their erections affected by endothelial damage, impaired autonomic functioning and vasospasm of the penile arteries.

Lower urinary tract disorder

Pressure can be exerted on the urethra or the urinary channel by benign (non-cancerous) swelling of the prostate. Other manifestations of this problem include urgency to urinate, hesitancy, slow stream, incomplete emptying of the bladder and post voiding dribbling. BPH in patients aged above 50 is also known to cause incontinence in 40-50% of the cases. Rather annoying, these symptoms are known to deteriorate the quality of life of such patients. Lower urinary tract disorder has been identified as a cause of erectile dysfunction in males aged between 20 and 30 in recent studies, yet in this case, it depends on the severity. Painful ejaculations and ejaculatory incompetence have also been identified as related to this condition. An extensive study on over 12000 males aged between 50 and 80 infers that the progression of ejaculatory disturbances and erectile dysfunction is heavily influenced by the severity of urinary symptoms, without regard to age and other risk factors. Still pending confirmation, several newer theories associate sexual and urinary symptoms with hyperactivity of the sympathetic nervous system of the penis and prostate, which causes contraction of the smooth muscles and penile arteries. Rho-kinase drew much attention of researchers of lower urinary tract symptoms and erectile dysfunction over the recent years. It is an enzyme responsible for affecting a number of cellular processes, including the contraction of smooth muscles.


Some medications prescribed as therapy for urinary symptoms might affect sexual function and thus be one of the causes for erectile dysfunction. One’s sexual desire is hampered by 5-alpha reductases such as Avodart and Proscar, for example. Side effects of these drugs also include reduced potency, impeded sexual desire and inhibition of ejaculation. Alpha-blocker medications (like Flomax) can cause ejaculatory problems, which has been reported by approximately 30% of patients taking similar drugs. Presumably, this is caused by the inhibitory influence of the drug on the sperm ducts and seminal vesicles. Sexual and urinary symptoms can be relieved by uroselective alpha-blockers phosphodiesterase type 5 inhibitors, like Uro-Xatral and Flomax. It is to be noted that, according to a warning issued by the US FDA, taking Viagra, Cenforce, Sildamax or any other ED drugs with sildenafil as the active substance must be avoided within four hours of taking any alpha-blockers. Some clinical studies, however, do confirm that there are no dangerous side effects associated with the combination of Flomax and Cialis or Uro-Xatral and Cialis for the treatment of erectile dysfunction and lower urinary tract symptoms.

Other findings

Application of the wedge-shaped tunica may often produce positive results in situations when the causes of erectile dysfunction (impotence) are unknown, curvature of the penis is less than 60° and penetration is difficult, but the penis is of normal length. Incision on the plaque and grafting it with natural or synthetic material can help if the penis is small and its curvature is over 60 degrees. Another recent study has discovered that non-palpable scarring at the septum of the penis can be due to Peyronie’s disease.

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