High blood pressure in your 30s or 40s is a warning sign of dementia in later life, according to Oxford researchers.
It increases by 62 per cent the chance of vascular dementia, the most common type after Alzheimer’s, they said.
Those at risk can protect themselves by taking common medications.
More than 150,000 people in the UK suffer from vascular dementia, which causes memory, speech and concentration problems. It is caused by diseased blood vessels reducing supplies to the brain.
Published in the Stroke medical journal, the findings suggest that blood pressure problems at a young age build up over time, leading to problems later in life.
The research team, based at the George Institute for Global Health at Oxford University, examined the medical records of more than four million Britons.
They found a 62 per cent increased risk of vascular dementia for those who had high blood pressure between the ages of 30 and 50. For the 51-70 age group, the increased risk was 26 per cent, and for the over-70s no change could be found.
The team found that high blood pressure was still a risk factor even after adjusting for the presence of stroke, the leading cause of vascular dementia.
Professor Kazem Rahimi, who led the study, said: ‘Vascular dementia rates are increasing all over the world and will pose a significant economic and social burden in both developed and developing countries.
‘So these results are particularly important.
‘We already know that high blood pressure can raise the risk of stroke and heart attack.
‘Our research has shown that high blood pressure is also associated with a significantly higher risk of vascular dementia.’
Increased blood pressure is a known risk factor for stroke and cardiovascular disease.
But until now studies were conflicting over the risks for vascular dementia, with several even indicating that low blood pressure was associated with an increased risk of dementia.
Dr Doug Brown, director of research and development at Alzheimer’s Society, said: ‘The results show that even in your 30s and 40s, high blood pressure can significantly raise the risk of vascular dementia later in life.
‘There is no silver bullet for preventing dementia, but everyone who is at risk of high blood pressure should get it checked regularly and receive effective treatment.’
Dr Rosa Sancho, head of research at Alzheimer’s Research UK, added: ‘This study has capitalised on the rich data held in electronic medical records to strengthen the link between high blood pressure and dementia risk, and suggest that mid-life could be a particularly important window for reducing the risk of future vascular dementia.
‘While it’s important that treatments are given to help control high blood pressure, this study doesn’t suggest that people without high blood pressure should be taking these medications specifically to reduce the risk of vascular dementia.’