What are the causes of erectile dysfunction?

Causes of Erectile Dysfunction

Erectile dysfunction results from five major categories of pathology: vascular disease (most common in men over 50), endocrine disorders, neurological conditions, anatomical/structural abnormalities, and psychological factors—with cardiovascular disease being the single most important cause to identify given its implications for mortality. 1

Vascular Causes (Most Common)

Vascular pathology accounts for approximately 40% of ED in men over 50 years and represents the most critical category to identify due to mortality implications 2:

• Atherosclerosis affecting penile vasculature causes endothelial dysfunction and decreased nitric oxide availability, the driving force of genital blood flow 1, 3
• Hypertension damages vascular endothelium and is strongly associated with ED 1, 4
• Hyperlipidemia accelerates atherosclerotic changes in penile arteries 1, 4
• Endothelial dysfunction represents the common pathway linking cardiovascular disease and ED, with ED often preceding coronary symptoms by 2-5 years 1, 5

ED should be considered an early warning sign of systemic cardiovascular disease and warrants immediate cardiovascular risk assessment 1, 5. New onset or progressive ED signals threatening ischemic heart disease even at asymptomatic stages 6.

Endocrine Causes

Hormonal abnormalities directly impair erectile function through multiple mechanisms 1:

• Diabetes mellitus is among the most common endocrine causes, affecting 35-90% of diabetic men with a fourfold increased risk compared to non-diabetic men 5
• Hypogonadism (testosterone <300 ng/dL) impairs both libido and erectile response to PDE5 inhibitors 1, 7
• Hyperprolactinemia suppresses testosterone production and sexual desire 1
• Thyroid disorders (both hypo- and hyperthyroidism) disrupt sexual function 1

In diabetic men specifically, the pathophysiology is multifactorial: autonomic neuropathy (odds ratio 5.0), peripheral neuropathy (odds ratio 3.3), peripheral arterial disease (odds ratio 2.8), poor glycemic control (odds ratio 2.3), and diabetes duration (odds ratio 2.0) all independently contribute 5.

Neurological Causes

Neurological conditions impair the neural pathways essential for erectile function 1:

• Spinal cord injury disrupts autonomic and somatic nerve pathways controlling erection 1
• Multiple sclerosis causes demyelination affecting erectile nerve signals 1
• Parkinson's disease impairs both central and peripheral nervous system control of erection 1, 2
• Peripheral neuropathy (particularly in diabetes) causes decreased smooth muscle relaxation of the corpus cavernosum, insufficient nitric oxide synthase function, impaired glans sensation, and abnormal motor function of erectile muscles 6, 5

Autonomic neuropathy correlates significantly with ED severity, particularly in type 1 diabetic patients 6.

Anatomical and Structural Causes

Physical abnormalities of penile anatomy directly impair erectile mechanics 1:

• Peyronie's disease causes penile curvature and plaque formation preventing adequate rigidity 1, 2
• Penile trauma damages erectile tissue or vasculature 1
• Surgical complications from pelvic surgery (prostatectomy, cystectomy, colorectal surgery) risk nerve damage to cavernosal nerves 1, 2
• Corporal erectile tissue alterations including smooth muscle degeneration occur particularly in diabetes 6

Psychological Causes

Psychological factors either cause or significantly contribute to ED, often coexisting with organic causes 1, 8:

• Depression is both a cause and consequence of ED, with worsening depressive symptoms preceding ED onset 6, 1
• Anxiety (particularly performance anxiety) triggers sympathetic nervous system activation that inhibits erection 1, 9
• Stress from work, financial, or life circumstances impairs sexual function 1
• Relationship problems including partner issues and communication difficulties contribute significantly 1, 8

The satisfaction of both patient and partner has become a critical outcome measure in ED management 8.

Medication-Induced Causes

Common culprit medications include antihypertensives, antidepressants, and tranquilizers—notably, diabetes medications themselves do NOT cause ED 6, 5:

• Antihypertensives: β-blockers, vasodilators, central sympathomimetics, ganglion blockers, diuretics, and ACE inhibitors all associate with ED 6, 5
• Antidepressants: Both tricyclics and SSRIs commonly cause sexual dysfunction 6, 5
• Antipsychotics impair erectile function through dopamine blockade 2
• Hormone treatments (particularly anti-androgens) suppress testosterone 2
• Histamine H2 antagonists (particularly cimetidine) have anti-androgenic effects 2

Lifestyle and Modifiable Risk Factors

Lifestyle factors create a pro-inflammatory state decreasing nitric oxide availability 3:

• Tobacco use is the most common substance causing or exacerbating ED through endothelial damage 4, 3
• Obesity and metabolic syndrome strongly associate with ED through multiple mechanisms 1, 4, 3
• Physical inactivity impairs endothelial function and cardiovascular health 1, 3
• Excessive alcohol consumption (>14 units/week for women, >21 units/week for men) impairs erectile function 1, 3
• Poor diet lacking fruits, vegetables, and whole grains promotes inflammation and endothelial dysfunction 1, 3

Lifestyle modifications including smoking cessation, regular exercise, weight loss, and Mediterranean diet patterns can restore erectile function in men with obesity or metabolic syndrome 1, 3.

Critical Clinical Pitfall

The most dangerous mistake is dismissing ED as merely a quality-of-life issue rather than recognizing it as a sentinel marker for life-threatening cardiovascular disease 1, 5. ED in a 45-49 year old diabetic man carries the same cardiovascular risk profile as a non-diabetic man over 70 years 5. Cardiovascular mortality risk doubles in men with ED, making aggressive cardiovascular risk factor assessment and modification essential 5.