Alzheimer’s may be caused by squeezed capillaries in the brain

Restricted capillaries in the brain may be a contributing factor in Alzheimer’s, a new study suggests. Scientists at University College London have found that amyloid beta protein, which leads to plaques forming in the brain, also squeezes blood vessels.

As a consequence, as much as half of the blood supply to the organ could be stopped, preventing oxygen and vital nutrients from reaching the brain. Poor blood flow to the brain has long been seen as an early warning sign for Alzheimer’s patients, but this latest breakthrough will help experts to understand how it occurs.

They hope that a drug with the ability to block amyloid beta from constricting capillaries could stop the cognitive decline in those with Alzheimer’s. Other experts in the field have warned that such a cure could be a long way off, but as with most breakthroughs in dementia, more research is required.

Dr Ross Nortley, of the department of neuroscience, physiology and pharmacology, led the research. He said: “Our study has, for the first time, identified the underlying mechanism behind the reduction of brain blood flow in Alzheimer's disease.

“Since reduced blood flow is the first clinically detectable sign of Alzheimer's, our research generates new leads for possible treatments in the early phase of the disease.”

Vascular resistance is the friction blood must overcome to make its way through the circulatory system and it mainly occurs in the capillaries. It is controlled by brain cells known as pericytes, which have been found to be out of sync in dementia patients in past studies.

To find out more, the scientists studied slices of brain tissue that had been gathered from 13 living people when they underwent neurosurgery. They analysed the impact of long term amyloid beta exposure on the pericytes and discovered that after 40 minutes, the diameter of the capillaries decreased by around 25 per cent.

Many scientists across the world are working on potential cures and treatments for dementia, as it is a growing problem. While there are currently 850,000 people in the UK living with the disease, the number is predicted by the Alzheimer’s Society to reach two million by 2051.

Meanwhile in the US, the Alzheimer’s Association puts figures at 5.8 million currently and set to rise to 14 million by 2050. The problem with finding treatments is that not enough is known about the disease and its causes.

Different groups of researchers are looking into myriad elements that may have an effect on the brain and memory in dementia sufferers, but they all have the same eventual aim - to eliminate the condition.

Anyone concerned about an elderly relative who is displaying early symptoms of Alzheimer’s, such as disorientation, memory loss or mood swings, should encourage them to see their GP.