What are the basic causes of erectile dysfunction?

Basic Causes of Erectile Dysfunction

Erectile dysfunction results from five primary pathophysiological mechanisms: vascular disease (most common, accounting for 40-60% of cases), neurological damage, endocrine disorders, psychological factors, and medication side effects. 1, 2

Vascular Causes (Most Common)

Atherosclerotic disease is the leading organic cause of ED, particularly in men over 50 years. 2, 3

• Hypertension, hyperlipidemia, and endothelial dysfunction impair penile blood flow through arterial insufficiency 2, 4
• Diabetes mellitus causes ED through multiple vascular mechanisms, including accelerated atherosclerosis and reduced penile blood flow (odds ratio 2.8) 5
• Small vessel disease damages the microvasculature of erectile tissue 6
• ED serves as a sentinel marker for cardiovascular disease—the same endothelial dysfunction affecting penile arteries predicts coronary artery disease by 2-5 years 1, 2
• Tobacco smoking directly alters penile arterial hemodynamics and accelerates existing atherosclerosis 6, 7

Neurological Causes

Autonomic neuropathy is the strongest predictor of ED in diabetic men (odds ratio 5.0), causing decreased smooth muscle relaxation and insufficient nitric oxide synthase function. 5

• Peripheral neuropathy impairs glans sensation and abnormal motor function of erectile muscles (odds ratio 3.3) 5
• Spinal cord injury, multiple sclerosis, and Parkinson's disease disrupt neural pathways necessary for erection 2
• Pelvic surgery carries risk of nerve damage leading to ED 3

Endocrine Disorders

Testosterone deficiency (total testosterone <300 ng/dL with symptoms) directly impairs erectile function and reduces PDE5 inhibitor efficacy. 1, 2

• Diabetes mellitus causes ED through autonomic neuropathy, endothelial dysfunction, and vascular disease—not through diabetes medications themselves 5
• Hyperprolactinemia and thyroid disorders contribute to hormonal ED 2
• Poor glycemic control directly correlates with ED severity (odds ratio 2.3) 5

Psychological Factors

Depression, anxiety, stress, and relationship conflict are primary contributors in psychogenic ED and secondary contributors in organic ED. 1, 2

• Performance anxiety creates a self-perpetuating cycle of erectile failure 1
• Depression is both cause and consequence of ED, with worsening depressive symptoms preceding ED onset 5
• The presence of nocturnal and morning erections suggests (but does not confirm) a psychogenic component 1

Medication-Induced ED

Antihypertensives and antidepressants are the most common medication causes—diabetes medications are NOT implicated as causative agents. 5

• Antihypertensives causing ED include β-blockers, vasodilators, central sympathomimetics, ganglion blockers, diuretics, and ACE inhibitors 5
• Antidepressants, including tricyclics and SSRIs, commonly cause sexual dysfunction 5
• Antipsychotics, hormone treatments, and histamine H2 antagonists (cimetidine) also contribute 3
• Tobacco use is the most significant substance-related cause 4

Anatomical/Structural Causes

• Peyronie's disease with penile plaque formation and deformity 1, 3
• Penile trauma and surgical complications 2
• Corporal erectile tissue alterations, including smooth muscle degeneration (particularly in diabetes) 5

Critical Clinical Implications

When evaluating ED, screen for diabetic complications first (autonomic neuropathy, peripheral neuropathy, retinopathy, nephropathy), then review medications focusing on antihypertensives and antidepressants—not diabetes medications. 5

• ED diagnosis provides a pivotal opportunity to assess cardiovascular risk, as ED predicts cardiac events as strongly as cigarette smoking or family history of myocardial infarction 1
• Diabetes duration increases ED risk (odds ratio 2.0), with ED prevalence in diabetic men aged 45-49 equaling that of non-diabetic men over 70 5
• ED prevalence in diabetic men ranges from 35-90%, conferring a fourfold increased risk compared to non-diabetic men 5