In majority of cases psychological reasons are implicated.
Vascular disease involving internal pudendal artery is thought to be one of the reasons for age related impotency.
A nerve injury or spinal cord injury may result in impotence.
Impotence may be an early symptom of diabetes mellitus, multiple sclerosis, tabes dorsalis etc.

Impotence, Erectile Dysfunction - SIGNS AND SYMPTOMS

Inability to get an erection is usually the only complaint.
In cases of penile dysfunction, premature ejaculation and spermatorrhoea may be found.
Depression often accompanies impotence. Severe depression can lead to impotence and impotence can lead to depression. It works both ways.

Impotence, Erectile Dysfunction - TREATMENT & HOMEOPATHIC Medicines

Homeopathy offers some very good medicines to treat this condition. But for proper treatment a homeopath must probe into the psychological reasons behind the condition. A detailed case history is necessary, including not only the sexual history, but also his general medical history, physical and mental characteristics etc. It is not easy give long term results if a homeopath is unable to make a judgment as to 'What went wrong?'. Also the 'when', 'where' and 'how' need to be answered too. long with the medicine such patients often need psychological counseling, especially so, if there are marked depressive traits present. This counseling can be done by an experienced homeopath or by a trained psychologist.

Some of the medicines commonly indicated in such conditions are agnus-castus, argentum-nit, china, conium, lycopodium, acid-phos, picric-acid, sabal-serr., selenium, strychninum, yohibinum, kali-brom, arnica, baryta-carb, nux-vomica etc. The selection of medicine varies from cae to case, and so do the results. But the food thing about homeopathic treatment is that you don't need to pop-a-pil every time you desire some action. Once you regain your ability to attain an erection, you usually get it for good.

Impotence, Erectile Dysfunction - CONVENTIONAL TREATMENT

Viagra, Cialis and similar drugs are now the medicines of choice. you need to pop-a-pill every time you....Also the medicine cannot be given to heart patients without medical examination.
Anti depressants are often given.
Penile paparazine injections were used previously.

Impotence, Erectile Dysfunction - WHAT ELSE CAN I DO?

Exercise daily -

it increases the level of male hormones
it increases the level of certain neurohormones, which result in mood elevation
it increases the peripheral blood circulation

Your Health is Sex Necessary?
Alan Farnham

Fans of abstinence had better be sitting down. "Saving yourself" before the big game, the big business deal, the big hoedown or the big bakeoff may indeed confer some moral benefit. But corporeally it does absolutely zip. There's no evidence it sharpens your competitive edge. The best that modern science can say for sexual abstinence is that it's harmless when practiced in moderation. Having regular and enthusiastic sex, by contrast, confers a host of measurable physiological advantages, be you male or female. (This assumes that you are engaging in sex without contracting a sexually transmitted disease.)

In one of the most credible studies correlating overall health with sexual frequency, Queens University in Belfast tracked the mortality of about 1,000 middle-aged men over the course of a decade. The study was designed to compare persons of comparable circumstances, age and health. Its findings, published in 1997 in the British Medical Journal, were that men who reported the highest frequency of orgasm enjoyed a death rate half that of the laggards. Other studies (some rigorous, some less so) purport to show that having sex even a few times a week has an associative or causal relationship with the following:

- Improved sense of smell: After sex, production of the hormone prolactin surges. This in turn causes stem cells in the brain to develop new neurons in the brain's olfactory bulb, its smell center.

- Reduced risk of heart disease: In a 2001 follow-on to the Queens University study mentioned above, researchers focused on cardiovascular health. Their finding? That by having sex three or more times a week, men reduced their risk of heart attack or stroke by half. In reporting these results, the co-author of the study, Shah Ebrahim, Ph.D., displayed the well-loved British gift for understatement: "The relationship found between frequency of sexual intercourse and mortality is of considerable public interest."