November 3, 2021
To understand what causes erectile dysfunction or ED, it is important to first review how an erection occurs. For a man to have an erection, a complex process takes place within the body.
An erection involves the central nervous system, the peripheral nervous system, psychological and stress-related factors, local factors with the erection bodies or the penis itself, as well as hormonal and vascular (blood flow or circulation) components. The penile portion of the process leading to an erection represents only a single component of a very complicated and complex process.
Erections occur in response to touch, smell, and auditory and visual stimuli that trigger pathways in the brain. Information travels from the brain to the nerve centers at the base of the spine, where primary nerve fibers connect to the penis and regulate blood flow during erections and afterward.
Sexual stimulation causes the release of chemicals from the nerve endings in the penis that trigger a series of events that ultimately cause muscle relaxation in the erection bodies of the penis. The smooth muscle in the erection bodies controls the flow of blood into the penis. When the smooth muscle relaxes, the blood flow dramatically increases, and the erection bodies become full and rigid, resulting in an erection. Venous drainage channels are compressed and close off as the erection bodies enlarge.
Detumescence (the process by which the penis becomes flaccid) results when muscle-relaxing chemicals are no longer released.
If one or more of the above physical and/or psychological processes is disrupted, erectile dysfunction can result. Erectile dysfunction describes a man’s inability to achieve and maintain an erection of his penis sufficient for mutually satisfactory intercourse with his partner.
In general, the cause of erectile dysfunction is divided into 2 types. Many men will have both:
- Psychological (mental) causes
- Physical or organic (having to do with a bodily organ or an organ system) causes
Erection problems usually produce a significant psychological and emotional reaction in most men. This is often described as a pattern of anxiety and stress that can further interfere with normal sexual function. This “performance anxiety” needs to be recognized and addressed by your doctor.
For some men, erectile dysfunction develops with age or may be related to depression or another psychological cause, such as widower syndrome.
Certain feelings can interfere with normal sexual function, including feeling nervous about or self-conscious about sex; feeling stressed either at home or at work; or feeling troubled in your current relationship. In these cases, psychological counseling with you and your sexual partner may be successful. One episode of failure, regardless of cause, may propagate further psychological distress leading to further erectile failure.
Physical causes for erectile dysfunction are much more common than psychological causes. In determining a physical (or organic) cause, your doctor will first rule out certain conditions, such as high blood pressure, high cholesterol, heart and vascular disease, low male hormone level, prostate cancer, and diabetes, which are associated with erectile dysfunction. In addition to these conditions, certain systemic and respiratory diseases are known to result in erectile dysfunction:
- Scleroderma (stiffening or hardening of the skin)
- Kidney failure
- Liver cirrhosis
- Hemachromatosis (too much iron in the blood)
- Chronic obstructive pulmonary disease
Often, one can restore sexual health by treating a condition such as high blood pressure with diet and/or exercise or by controlling diabetes or other chronic diseases. Nutritional states, including malnutrition and zinc deficiency, may be associated with erectile dysfunction and can also be treated with diet.
Almost any disease can affect erectile function by altering the nervous, vascular, or hormonal systems. Various diseases may produce changes in the smooth muscle tissue of the penis or influence mood and behavior.
Diseases that affect the nervous system and are commonly associated with erectile dysfunction include:
- Multiple sclerosis
- Guillain-Barré syndrome
- Alzheimer disease
- Parkinson disease
- Vascular diseases account for nearly half of all cases of erectile dysfunction in men older than 50 years.
Vascular disease includes atherosclerosis (fatty deposits on the walls of the arteries, also called hardening of the arteries), a history of heart attacks, peripheral vascular disease (problems with blood circulation), and high blood pressure.
Prolonged tobacco use (smoking) is considered an important risk factor for erectile dysfunction because it is associated with poor circulation and its impact on cavernosal function.
Blood diseases, such as sickle cell anemia and leukemias, are also associated with erectile dysfunction.
An imbalance in your hormones, such as testosterone, prolactin, or thyroid, can cause erectile dysfunction. The following hormonal (or endocrine) conditions are commonly associated with erectile dysfunction:
- Hyperthyroidism (overactive thyroid gland)
- Hypothyroidism (underactive thyroid gland)
- Hypogonadism (leads to lower testosterone levels)