People with high blood pressure that gets even higher at night are at increased risk of vascular disease and memory decline, according to research.
While most people’s blood pressure goes down during the night, scientists have found those who experience “reverse dipping”, where nighttime pressure stays the same or even goes up, have small areas in the brain that appear damaged.
Study author Dr Adam M Brickman, of Columbia University in New York, said: “These results add to the mounting evidence that shows the importance of vascular risk factors in contributing to memory problems.
“They also point to the potential impact of preventing high blood pressure through efforts such as maintaining a healthy weight, being physically active and having a healthy diet.”
The study, published in the journal Neurology, involved 435 people with an average age of 59.
Their blood pressure, defined as a 24-hour average of more than 130/80 mmHg, was monitored at home every 15 minutes during the day and every 30 minutes at night.
The study participants underwent brain scans and took memory tests.
More than half of the people (59%) were found to have high blood pressure or were taking medication for the condition.
Among them, the blood pressure dipped at night in half of the people, stayed the same in 40%, and in 10% it went up.
Those with high blood pressure and reverse dipping had more than twice the amount of white matter hyperintensities, small areas in the brain that appear damaged from vascular disease, and lower scores on a memory test than the other participants.
According to the researchers, participants with reverse dipping had average scores of about 33 while the others had average scores of about 40.
Dr Brickman said: “It appears that reverse dipping may amplify the effects of high blood pressure on people’s cerebrovascular health and associated cognitive abilities.”
The researchers said longer studies are needed to determine whether the condition does indeed lead to white matter changes and memory problems.
Commenting on the research, Dr Sara Imarisio, head of research at Alzheimer’s Research UK, said: “High blood pressure, particularly in midlife, is a strong risk factor for dementia.
“While age and genetics play an important role, research also shows that up to a third of our risk for dementia may be modifiable.”
She added: “This study suggests that it’s not just daytime blood pressure that affects dementia risk but blood pressure levels throughout the day and night.
“Although the phenomenon of reverse dipping during the night is an accepted measure of cardiovascular risk, the effect that reverse dipping has on dementia risk is a relatively understudied area of research.”
