Someone I know who suffers from migraines, high blood pressure and high cholesterol came to me the other day because her doctor had ordered an MRI of her brain, and when her results came back, he gave her ambiguous news. "Nothing to worry about", he said, "it's all normal, with the exception of some white matter disease...". Unfortunately my friend was too shy to ask her doctor what he had meant by that, so she gave me a call me the next morning to ask what it means to have "white matter disease". Of course, I first had to explain the meaning of the term "white matter', which in essence is the area of the brain and spinal cord where the connections between brain cells (also called neurons) are located. In the brain, the white matter is irrigated by tiny blood vessels, which are the first to be affected by atherosclerosis.
I continued to explain that white matter disease purely refers to MRI or CT findings, which show that the white matter of the brain has been affected by certain disease processes, usually chronic in nature, such as high blood pressure, diabetes, high cholesterol, and the like. A small amount of these changes is almost expected to appear with age, but large amounts of it are associated with specific diseases such as multiple sclerosis, wilson's disease, and even Alzheimer's disease.
She the asked me what this meant for her given that other than her migraines she feels perfectly healthy. I told her that in fact there is no need to panic, but it is probably time for her to start giving her best effort at controlling her stroke risk factors. After all, people with high stroke risk factors are known to have a higher burden of white matter disease.