How an erection is supposed to work
Four things have to happen in order. Arousal generates a signal in the brain. Nerves carry it down the spinal cord to the pelvis. The arteries feeding the penis relax and open, letting blood rush in at up to forty times the resting rate. And the veins that would normally drain that blood get compressed by the swelling tissue, trapping it in place.
Erectile dysfunction is any one of those four steps failing. That is why 'ED' is a symptom rather than a diagnosis — and why the useful question is never *do I have ED* but *which step is failing, and why*.
The vascular causes — the big one
In men over 50, narrowed or stiffened arteries are the most common single cause. The same plaque that builds up in the coronary arteries builds up everywhere, and it reduces both the volume of blood arriving and the pressure that holds it in.
The drivers are the familiar ones: high blood pressure, high cholesterol, diabetes, smoking, obesity and inactivity. Each of these damages the endothelium — the single-cell lining of every blood vessel — which is what produces the nitric oxide that tells arteries to open in the first place.
The nerve causes
The signal has to reach the arteries to open them. Anything that interrupts the nerve pathway can cause ED even when the blood supply is perfect.
- Diabetes damages small nerves as well as small vessels, which is why it is such a strong risk factor — men with diabetes develop ED around ten to fifteen years earlier on average.
- Prostate surgery for cancer runs close to the nerve bundles either side of the prostate. Even nerve-sparing technique causes a period of dysfunction, and recovery takes months to years.
- Pelvic radiation damages both nerves and vessels, usually with a delayed onset.
- Spinal problems, multiple sclerosis, Parkinson's disease and stroke can all interrupt the pathway at different points.
Medications — check this before anything else
A large share of ED in this age group is caused or worsened by a drug taken for something else. It is the most fixable cause on this page and one of the most frequently missed, largely because men do not connect a blood pressure tablet with what happens in bed.
The usual suspects are older beta blockers, thiazide diuretics, SSRIs, finasteride, some antipsychotics and certain antihistamines. Never stop a prescribed drug yourself — but do take the list to your prescriber and ask whether an alternative exists. Full list and what to swap.
Hormones
Testosterone falls by roughly one percent a year after about age 40. That gradual decline is normal and, on its own, is rarely the cause of ED — testosterone drives desire more than it drives blood flow.
Genuinely low testosterone is a different matter and does warrant treatment, but it needs two morning blood tests to diagnose, not a questionnaire. Thyroid problems and high prolactin are less common but worth checking if the picture does not add up.
The psychological side
Anxiety triggers adrenaline, and adrenaline does exactly the opposite of what an erection requires: it constricts arteries. So performance anxiety is not 'all in your head' in any meaningful sense — the mechanism is as physical as plaque.
What makes this important after 50 is the feedback loop. A minor vascular problem causes one failure. The worry about a repeat causes the second. Within a few months a modest physical issue has become a much larger psychological one, and treating only the physical side leaves half the problem in place.
Working out which one is yours
You cannot diagnose yourself, but you can arrive at your appointment with far better information than most men bring. Two questions do most of the work.
| What you notice | What it points toward |
|---|---|
| Still wake with erections, but lose them with a partner | The hardware works. Points toward anxiety, relationship factors, or depression. |
| Gradual decline over months or years, including morning erections | Points toward vascular or hormonal causes — the typical over-50 pattern. |
| Sudden and complete, with a clear start date | Points toward a new medication, surgery, injury, or a major psychological event. |
| Erection starts fine but will not hold | Points toward venous leak — the trapping step failing rather than the filling step. |