Causes of erectile dysfunction

From the clinical point of view, the causes may be classified into a few basic groups: organic, psychological and iatrogenic. They may constitute separate conditions, but usually two or more causes coexist, significantly disturbing the treatment process in which standard methods are used.

Until recently, the most common cause of ED was believed to be the psychological factors. According to the present state of knowledge, organic and mixed causes contribute the most.

Psychogenic ED

Factors of erectile dysfunction may be related both to the mental condition of the man, as well as to his relationships. It has been long known that nerves, lack of sexual arousal, as well as decisive stressful situations or depression may lead to the deterioration of the erectile function. The mechanism of psychogenic erectile dysfunction is very complex and has not been fully understood so far. There are specific situations and emotional states that predispose to this kind of dysfunction. They include:

• Fear of sexual intercourse
• Depression, stress in everyday life
• Fear of unwanted pregnancy and sexually transmitted diseases
• Problems with relationships
• Previous bad experiences connected with sex

The psychological background of the dysfunction may be suspected in men with so called morning erections or those able to achieve an erection through masturbation. However, it shall be underscored that the term ‘psychogenic erectile dysfunction’ should not be used in case of unknown or uncertain etiology of the disease. The diagnosis is based mostly on a conversation with the patient or on psychological tests and it is usually a diagnosis of exclusion – the patient should not be subjected to psychotherapy before elimination of other possible causes of ED. 

Organic ED

This group includes many diseases. For a better overview, they may be divided into the following subgroups:

• Neurogenic

This is a group in which the transmission of impulses to nerve endings in cavernous bodies is disturbed and thus the cascade is not activated which  leads to the release of relaxants of vascular smooth muscles increasing blood inflow to the penis. Pathomechanisms of such disorders are diverse and depend on the cause. This may be: the process of damage of the myelin sheath (multiple sclerosis), neuronal degeneration by excessive deposition of glucose (so called diabetic neuropathy) or the lack of nervous impulse transmission caused by a disrupted pathway (injuries, e.g. of the spinal cord). Neurogenic erectile dysfunction is relatively hard to treat because the nervous system has a limited capability of regeneration, and its diseases are not easy to reverse.

• Hormonal

Hormonal disorders are connected with an abnormal activity of the endocrine glands (e.g. pituitary gland or thyroid) and pathologies of the gonads, which play important roles in the hormonal regulation. These changes lead to an impaired production of sex hormones - their blood level is decreased, which results in e.g. loss of sex drive or ability to maintain erection. It is also worth mentioning that disorders of secretion of such basic hormones as the thyroid hormone or prolactin, may have a significant influence on the quality of erection. Due to a relatively high prevalence of such disorders, accurate laboratory diagnostics including tests of blood or urine level of sex hormones is important.

• Vascular

Vascular causes of erection are detected in the majority of cases. Although vascular ED may follow from an injury or congenital malformation, the most common cause still remains the atherosclerosis. Systemic deposition of cholesterol in arteries concerns also the arteries of cavernous bodies. This leads to occlusion of their  lumen up to a diameter which inhibits blood inflow necessary for an erection. Moreover, cholesterol deposits in the vessels tend to calcify, which significantly reduces the dilatory potential of the arterial smooth muscles.

Vascular mechanism of erectile dysfunction is very similar to the one seen in coronary disease, infarctions, or brain strokes. Damaged vessels cannot efficiently supply organs with blood, which leads to their ischaemia or loss of function. Taking into account that the diameter of the arteries supplying the penis is lower than the one of coronary arteries, it is common that the problem with sexual function significantly precedes the appearance of changes in the heart or other organs. Therefore, it is so important to conduct a wider range of diagnostic procedures in patients with erectile dysfunction. It has also been shown that diabetes and increased levels of blood glucose are connected with erectile dysfunction. This mechanism has not been fully clarified but endothelial damage may be of significance (coexisting with the damage of neurons transmitting nervous impulses to the penis). This group of disorders includes hypertension, but also vascular malformations and dysfunction of endothelium which is responsible for NO (nitric oxide) secretion.

• Medication-induced

There are many medicines that influence the ability to have an erection, and most of them are prescribed as a part of psychiatric treatment, hormonal treatment or chemotherapy. However, medicines used in the therapy of hypertension and coronary diseases are of the highest influence. Due to that, a proper selection of the drugs, taking into account patient’s comorbidities, is extremely important. A classic example would be the treatment of hypertension in patients with a benign prostatic hyperplasia, in which the difficulties connected with erection (following from prostatic hyperplasia) are enhanced by incorrectly selected hypotensive agents. There are many examples of such interactions. Unfortunately, they tend to be disregarded in treatment planning, which reduces patient’s quality of life or leads to his/her non-compliance.

• Other

Sexual dysfunction in men may also be caused by many other factors and conditions, with the most frequent ones being:

• Injuries of sex organs due to trauma or surgery
• Prostate hyperplasia
• Smoking habit
• Alcohol
• Drugs

Erectile dysfunction may have different aetiologies and certain causes are age-related. In the group of teenagers and young men, the problems are usually psychologically-related, mostly connected with complexes, lack of experience or fear of unwanted pregnancy. In middle-aged men, the main factors of erectile dysfunction are stress, the fact of being overworked, as well as problems in personal relationships. Organic causes, including atherosclerosis or diabetes, are of increasing importance. The organic background in sexual dysfunction starts to dominate with age and is present in most of the patients in their mature years. The largest group includes dysfunction connected with the cardiovascular system and with conditions causing changes in vessels supplying blood to the penis.