Parasympathetic input allows erection by relaxation of trabecular smooth muscle and dilation of the helicine arteries of the penis. This leads to expansion of the lacunar spaces and entrapment of blood by compressing venules against the tunica albuginea, a process referred to as the corporal veno-occlusive mechanism. The tunica albuginea must have sufficient stiffness to compress the venules penetrating it so that venous outflow is blocked and sufficient tumescence and rigidity can occur.
Accurate statistics are lacking on how many men are affected by the condition because it is often underreported, but it is estimated that about half of men over 40 in Canada have frequent problems achieving or maintaining an erection. The number of men suffering from erectile dysfunction increases with age, but it is not considered a normal part of aging. The majority of cases can be successfully treated.
In exchange for political impotence, they would be mostly left alone and allowed to get rich. — Paul Mozur, New York Times, "Inside China’s Dystopian Dreams: A.I., Shame and Lots of Cameras," 8 July 2018 Their suspicion is compounded by rumors that the polio vaccine causes impotence, death and, ironically, paralysis. — Meher Ahmad, New York Times, "Pakistan Has Just One New Polio Case, but Isn’t Declaring Victory Yet," 20 May 2018 Fighting back, even as an exercise in impotence, did a lot for McCain. — Alex Horton, Washington Post, "John McCain rebelled at the Naval Academy — and as a POW — long before he was a Senate maverick," 3 May 2018 Feelings of desperation and impotence are being felt throughout Central America, where the lawlessness, endemic poverty and levels of gang violence akin to war zones that have driven so many families from their homes show little signs of abating. — Washington Post, "Violence keeps Central Americans coming to US despite Trump," 21 June 2018 Uruguay's attacking impotence forced Oscar Tabarez to make two changes before the hour mark, with Nahitan Nandez and Giorgian de Arrascaeta replaced by Carlos Sanchez and Cristian Rodriguez. — SI.com, "Egypt 0-1 Uruguay: La Celeste Start With a Win as Gimenez Header Breaks Pharaohs' Hearts," 15 June 2018 It was fueled by physician ignorance and impotence, the habit of looking askance at patients whose symptoms could not be explained, and the arrival in the U.S. of German psychoanalysts who were disciples of Sigmund Freud. — Jim Carrier, STAT, "Lobotomies were once used to treat this gut disease, part of a shameful medical history," 12 June 2018 That signing's top attribute had better be goal-scoring, because the Sounders simply can't sustain with this level of attacking impotence. — Avi Creditor, SI.com, "The MLS XI, Week 14: Don't Hold Your Breath for an MLS Cup Threematch," 4 June 2018 Prostate cancer surgery in particular can have severe results, including incontinence and impotence. — Steven Petrow, Washington Post, "Watching but not treating cancer can be hard. Sometimes it’s the right approach.," 20 May 2018
The risk of impotence increases with age. It is four-fold higher in men in their 60s compared with those in their 40s according to a study published in the Journal of Urology (2000;163:460-463). Men with less education are also more likely to experience impotence, perhaps because they tend to have less healthy lifestyles, eat a less healthy diet, drink more and exercise less. Physical exercise tends to lessen the risk of impotence.
Sexual dysfunction and ED become more common as men age. The percentage of complete ED increases from 5% to 15% as age increases from 40 to 70 years. But this does not mean growing older is the end of your sex life. ED can be treated at any age. Also, ED may be more common in Hispanic men and in those with a history of diabetes, obesity, smoking, and hypertension. Research shows that African-American men sought medical care for ED twice the rate of other racial groups.