Blood Pressure and the Brain
We have known for almost a century that regions of the brain are involved in the control of blood pressure.
Yet over the last three decades most of the emphasis in research into hypertension (high blood pressure) has focused on blood vessels, the heart and kidneys.
Now research from Bristol University in England has been published in this month’s issue of the journal Hypertension, and it may put the brain back into the center of research into the causes and treatment of high blood pressure.
Working with rats, the researchers isolated a protein called JAM-1 (junctional adhesion molecule-1), that is located in the walls of blood vessels in the brain. It appears to trap white blood cells causing obstruction of blood flow in some of the smallest blood vessels. This can cause inflammation and result in poor oxygen supply to the brain, which may in turn trigger events that raise blood pressure.
Though this work is in its early stages, this is exciting stuff: if confirmed, it might be possible to treat hypertension with drugs that reduce blood vessel inflammation and increase blood flow within the brain.
It also ties in with other recent research from Imperial College, London and Oxford University, in which a team of neurosurgeons and physiologists discovered changes in blood pressure while fitting brain electrodes to 15 patients for pain control.
Deep brain stimulation involves placing very thin electrodes on very exact locations in the brain and is already used to relieve pain and to help Parkinson’s disease patients with their movement.
The researchers found that they could make patients’ blood pressure increase or decrease by stimulating very specific regions of the brain with the electrodes. Regions that have been associated with blood pressure control in the past. If they stimulated an area deep down in the midbrain called the ventral periventricular/periaqueductal gray matter, blood pressure went down, and if they stimulated the dorsal periventricular/periaqueductal gray matter it went up.
Nobody is suggesting that we should start sticking electrodes in peoples’ brain, but this chance observation may have profound implications, particularly for people who drop their blood pressure too far when they are treated with standard medicines.
These two pieces of research may also help explain why a balanced inflammation–reducing diet and relaxation may both reduce blood pressure.