Why are eyes a window to dementia?

Tiny yellow spots in the back of the eye could be an early warning sign of dementia, new research suggests. The spots, called “hard drusen”, are small deposits of fat and calcium that form in a layer underneath the retina and can be seen in scans. The spots are a common symptom of ageing and often seen in people over 40, and they have long been thought to be harmless. But new research from Queen’s University in Belfast, shows how Alzheimer’s sufferers have many more of the yellow or white hard dots than healthy people. The study also suggests changes in blood vessels in the eye could be linked to the development of dementia. Scientists say scanning for the spots and examining the eye's blood vessels could be a “valuable tool in Alzheimer's disease monitoring”. Researchers hope eye scans could be a cheaper way of detecting brain disease plus, they say, they are quicker and less invasive David Allamby, laser eye surgeon and medical director of London's Focus Clinic said: “The eyes have long been thought of as a window to the body, where the health of the eye is a reflection of the general health of the person. You can often detect the early signs of heart disease, diabetes and even brain tumour through a simple eye test. And the eye's retina is part of the central nervous system, and shares many structural and functional features with the brain. So examining the eye could be a monitoring tool for the changes in the brain.” The study was led by Queen's University's Dr Imre Lengyel whose team scanned the eyes of 117 patients aged between 60 and 92. He discovered 25 per cent of patients have yellow spots behind eyes.