Women with high blood pressure in their forties have a 73 percent higher risk of dementia, a new study has found.
Researchers admitted they were stunned by the extraordinarily high figure – and also to see that the risk only seemed to apply to women.
Even though more men suffer from hypertension, their chance of developing the neurodegenerative disease was unaffected by blood pressure.
Experts warn the findings from Kaiser Permanente in California show gender likely plays a larger role in the disease than we think.
Researchers at Kaiser Permanente in California admitted they were stunned by the extraordinarily high figure – and also to see that the risk only seemed to apply to women
‘Previous research has shown links between hypertension and dementia among both sexes so this work suggesting a link in women but not men is surprising,’ said Dr Doug Brown, director of research at Alzheimer’s Society.
The study, published today in the journal Neurology, tracked 7,238 people from the mid 1960s.
At the start of the study, the participants had an average age of 33, and they all had their blood pressure monitored. They were monitored again in the mid-1970s.
About 22 percent of the participants had high blood pressure in their 30s – 31 percent of men and 14 percent of women.
In their 40s, 22 percent overall had high blood pressure – 25 percent of men and 18 percent of women.
In 1996, they got back in touch with the 5,646 patients who were still alive and part of the Kaiser health system. They assessed which ones had been diagnosed with dementia, which hadn’t, and tracked them all for another 15 years.
Over time, it became clear that the women with a high blood pressure years earlier were more likely than not to have developed the disease.
‘High blood pressure in midlife is a known risk factor for dementia, but these results may help us better understand when this association starts, how changes in blood pressure affect the risk of dementia and what the differences are between men and women,’ said study author Dr Rachel Whitmer.
Having high blood pressure in early adulthood, or in one’s 30s, was not associated with any increased risk of dementia.
But having high blood pressure in mid-adulthood, or in one’s 40s, was associated with a 65-percent increased risk of dementia for women.
Women who developed high blood pressure in their 40s were 73 percent more likely to develop dementia than women who had stable, normal blood pressure throughout their 30s and 40s.
Dr Brown added: ‘It is a well-established fact that high blood pressure in mid-life can increase our chances of developing dementia in later life.
‘The younger age of people involved in this study compared to previous ones may partly explain the difference, but as this new research goes against the grain we need to see more studies to fully understand possible sex differences in blood pressure and dementia risk.
‘We should be mindful that this study tested the blood pressure of people in a particular health-scheme in Northern California in the 1960s and 70s.
‘Since then there have been advances in how blood pressure is treated – so it’s not clear how relevant the findings of this study are to [other populations].’