In 1995, it became clear that 55% to 80% of the causes of impotence are physical, such as a blood vessel disease; anxiety is responsible for very few cases of impotence, and then overwhelmingly in young men. Emotional states such as anger, depression, and marital discord may worsen physically induced erectile dysfunction. This corrects the previous picture, namely, that 90% of chronic impotence resulted from various emotional conflicts; the remaining 10% was held to be psychological in nature.
Age as such does not contribute to impotence; it is the health problems of older men that hamper erectile function: cardiovascular disease, diabetes, surgery for prostate cancer, side effects of medications, and hormonal aberrations. The most common cause of erectile dysfunction in men over 60 is constraint of the blood flow by atherosclerotic plaques in the penile or pelvic arteries. Diabetes and cocaine abuse hasten atherosclerosis.
Damage to the nerves involved in erection causes impotence. Nerves can be damaged by diabetes, prostate cancer surgery, multiple sclerosis, Parkinson's disease, spinal cord or pelvis injury. Hormonal abnormalities are rare, although an underactive or overactive thyroid can also bring about erectile dysfunction. More than 200 prescription drugs interfere with erectile function, including those for high blood pressure, psychosis and depression.
Regular erections help keep the penile blood vessels healthy. The longer a man goes without an erection, the greater the damage to the lining of the blood vessels, damage which eventually can make erection impossible.
According to a professor of urological surgery and oncology, smoking is the most preventable cause of impotence. Smoking can affect the circulatory system which in turn adversely affects the male sexual function. In one study, smokers had a 50% higher incidence of impotence than nonsmokers.
From the perspective of the Catholic Church impotency is the state of one who is incapable of normal sexual relations and as such the man cannot validly contract marriage since he is physically incapable of realizing its object. The impotency which is a cause of nullity is the incapacity of having conjugal relations, not incapacity of engendering, in other words, sterility. No one is presumed impotent once he has reached the legal or real age of puberty; consequently, no one, except eunuchs, can be prevented by authority from marrying.
Estimates suggest that 5% of men at 40 years of age are completely impotent and 15% at 70 years of age. In addition, 10% have moderate to chronic impotence at age 40; the figure is 30% at 70 years. Men can ordinarily remain potent into their 90's.
In Europe an estimated 36 million men suffer from erectile dysfunction. In the USA, the number is 30m, of which 15-20m are over 40. Around half of these have taken the drug Viagra since it was approved in 1998.
In Britain in 1998, 3m men suffer erectile dysfunction, and 1 in 10 men experience a sexual problem at some time in their life. 25% of the men over 40 who request medical assistance for impotence have been unfairly turned down by general practitioner doctors on the mistaken grounds that they are too old.