Dr Amir Khan reveals the 'life-saving' device everyone over 40 should have at home - and it costs under £20

A blood pressure monitor, the doctor says, costs about £15 from a local pharmacy, and it's key for managing high blood pressure, one of the risk factors for dementia.

"I would say that every person aged over 40 should be checking their blood pressure regularly at home,” said Dr Khan, who is also woman&home's resident GP. "Good blood pressure improves blood flow to the brain, [reducing] the risk of dementia."

The doctor recommends using the blood pressure monitor to take readings a few times a week at different times of day, using the average for the best results. "Check your blood pressure maybe once or twice a week if it's normal. Sit down or relax for 30 minutes. Check it then. Do it morning and evening. Vary it throughout the week," he said.

"It's the average reading you're interested in, not just one-off readings," he noted. "And if your average readings are high, speak to your doctor about managing your blood pressure, but this could be a lifesaver."

Hypertension, or high blood pressure, is estimated to affect around one in three men and women in England, and the charity Blood Pressure UK estimates that over five million people don’t know they have it.

The condition has been labelled the “silent killer” as it has few symptoms but increases the risk of heart attack, stroke and vascular dementia.

The doctor has previously shared how to lower blood pressure with simple lifestyle changes and nutrition habits, including how beetroot juice can help. He said: "You can help keep your blood pressure healthy by stopping smoking, managing alcohol consumption, eating wholefoods, doing regular movement, sleeping well, and managing stress levels (easier said than done, I know)."

How to use a blood pressure monitor at home

• Sit quietly for 5 minutes before measuring, the doctor suggests.
• Rest your arm on a table at heart level
• Take 2 readings, 1 minute apart, morning and evening for 7 days
• Record the results and average them

If you’re unsure how to use the blood pressure monitor or interpret the results, you can ask a nurse or your GP, and always read the instructions that come with your device.

The doctor has previously said that any readings higher than 135-140/85-90 need to be looked at by a healthcare professional.

What's a normal blood pressure reading?

• Ideal: under 120/80 mm Hg
• High: 140/90 mmHg or more (or 135/85 mmHg if checking at home, the doctor wrote on Instagram)

What's the link between high blood pressure and dementia?

Evidence shows a strong link between high blood pressure and the risk of developing dementia, with studies demonstrating that those diagnosed with high blood pressure between 40 to 64 years old were more likely to develop the condition (vascular dementia in particular) in later life.

Alzheimer's Society says vascular dementia is the second most common type, after Alzheimer's disease. It's caused by a lack of blood flow to the brain, which starves the brain of oxygen and the nutrients it needs.

If you go and see a doctor with concerns about your memory, Dr Khan says it's likely they will run a couple of tests. "We would take a full history from you and perhaps run through a memory test," he said on the show. "And if we think you've scored highly enough, we'll look for other causes of memory issues like vitamin deficiencies. We might then refer you to a memory clinic, who then may go on to do scans and talk through treatment for dementia if that is what you're diagnosed with."