This is the 56th instalment in a series on dementiaincluding the research into its causes and treatment, advice for carers and stories of hope.
If you unwound all the blood vessels inside the body and measured their length, you might be surprised at the distance they covered: 96,560km (60,000 miles), with 644km of them inside the head.
The vessels in the head bring oxygen and nutrients to the brain and help rid it of toxins and waste products so it can work optimally. Any leaks or blockages will impede this.
This is why obstructions such as blood clots and build-ups of plaque that narrow blood vessels, caused by high cholesterol, can harm brains, and why medical journal The Lancet added high levels of LDL cholesterol – the bad kind – to its list of modifiable risk factors for dementia.
One study found that LDL cholesterol measured in midlife – in those under 65 years – is associated with dementia risk more than 10 years later.
Blood-vessel health is also linked to the health of the blood-brain barrier, which acts as a filter to protect the brain from infections that may rage in the body, for example.