Blood pressure
The single most modifiable driver of stroke and heart disease, and the one number most people could know and don't.
settledLarge, consistent evidence base. Unlikely to reverse.Revised 05 Jun 2026
A home monitor with an upper-arm cuff. Wrist devices are less reliable.Photograph: Hush Naidoo Jade Photography / Unsplash
Definition
The pressure blood exerts on artery walls, written as two numbers: systolic (during the heartbeat) over diastolic (between beats), in millimetres of mercury. Hypertension is conventionally defined as a reading at or above 140/90 mmHg on repeated measurement, though treatment thresholds vary by guideline and by individual risk.
Why it dominates
Raised blood pressure is the leading modifiable risk factor for stroke, ischaemic heart disease, heart failure, chronic kidney disease and vascular cognitive impairment — and it appears in the Lancet Commission’s list of modifiable dementia risk factors as well.
Two features make it unusually important in the context of ageing:
- It is silent. There are no reliable symptoms until organ damage has occurred. Most people with hypertension do not know.
- It rises by default. Arterial stiffening with age pushes systolic pressure up across the population, so the question is not whether yours will drift but whether anyone is watching.
What moves it
In rough order of effect for someone in the ordinary range:
| Lever | Typical effect |
|---|---|
| Antihypertensive medication | Large, reliable, cheap |
| Weight loss where there is excess weight | Several mmHg per few kg |
| Sodium reduction | A few mmHg, more in salt-sensitive people |
| Regular aerobic exercise | A few mmHg, sustained |
| Reduced alcohol intake | Meaningful in heavy drinkers |
| Potassium-rich diet | Modest, additive to sodium reduction |
Nothing on the lifestyle side substitutes for medication when pressure is high enough to warrant it. The relationship works the other way: they add.
How to measure it properly
Home monitoring beats a single clinic reading, largely because of white-coat effects. The protocol matters more than the device:
- Upper-arm cuff, correctly sized. Wrist monitors are less reliable.
- Sitting, back supported, feet flat, arm at heart height, five minutes still.
- No coffee or exercise in the preceding half hour.
- Two readings a minute apart, morning and evening, for several days. Average them. A single reading means very little.
Open questions
How low to push treated pressure in older adults is genuinely contested — intensive targets reduce cardiovascular events but increase falls and kidney events in some groups, and the balance shifts with frailty. That is a decision for a clinician with your history, not a rule.