The epidemiology and pathophysiology of erectile dysfunction.

PURPOSE: Published studies on the epidemiology of erectile dysfunction and the physiology/ pathophysiology of erectile function are reviewed.
MATERIALS AND METHODS: A literature search of more than 400 studies of the epidemiology and pathophysiology of impotence and erectile dysfunction published during the last 3 decades was conducted and the most pertinent articles are discussed.
RESULTS: It has been estimated that the prevalence of erectile dysfunction of all degrees is 52% in men 40 to 70 years old, with higher rates in those older than 70 years. Erectile dysfunction has a significant negative impact on quality of life. Risk factors for erectile dysfunction include aging, chronic illnesses, various medications and cigarette smoking. A nitric oxide/cyclic guanosine monophosphate mechanism has an important role in mediating the corporal smooth muscle relaxation necessary for erectile function. Other mechanisms involving neuropeptides, gap junctions and ion channels also may modulate corporal smooth muscle tone. Erectile dysfunction can be due to vasculogenic, neurogenic, hormonal and/or psychogenic factors as well as alterations in the nitric oxide/cyclic guanosine monophosphate pathway or other regulatory mechanisms, resulting in an imbalance in corporal smooth muscle contraction and relaxation.
CONCLUSIONS: Erectile dysfunction is a common condition associated with aging, chronic illnesses and various modifiable risk factors. Normal penile erection is a hemodynamic process that is dependent on corporal smooth muscle relaxation mediated by parasympathetic neurotransmission, nitric oxide, and possibly other regulatory factors and electrophysiological events. As more knowledge is gained of the physiology and regulatory factors that mediate normal erectile function, the mechanisms involved in the pathophysiology of erectile dysfunction should be further elucidated.