Magnetic resonance imaging (MRI) can be used to diagnose various ailments of the brain, from dementia to tumors. This diagnostic tool can identify gray matter and white matter hyperintensity that could indicate deeper problems. When white matter hyperintensity appears, it is usually a result of old age, indicating a loss of blood flow; however, scientists have devised ways to measure how that hyperintensity can also point to dementia and other conditions.
White matter hyperintensity can occur in various places in the brain. When it occurs in the basal ganglia part of the brain, this is called subcortical hyperintensities. Near lateral ventricles, a periventricular hyperintensity can be observed. Finally, what is known as deep hypertensity can be observed in the depths of the brain's white matter.
No matter where in the brain it occurs, white matter hyperintensity reflects what is called demyelination, a deterioration of neural pathways caused by decreasing blood flow and/or disease. Affecting overall signal strength in the brain, when these hyperintensities are found in white matter at higher than average levels, it is likely to indicate either dementia or a higher probability that dementia will someday occur, according to recent studies, including a 2008 inquiry at Harvard University. Also, those with clinical depression or bipolar disorder are nearly three times more likely to have evident hyperintensities discovered during an MRI.
Scientists in 2011 are honing in on other possible links between white matter hyperintensity and a higher propensity for other human maladies like diabetes, Alzheimer's disease, strokes, multiple sclerosis and heart disease. Also referred to as brain rust, these particular hyperintensities are gaining interest in the scientific community, which, until the 21st century, dwelled primarily on research of gray matter. The consensus as of 2011 is that, though gray matter is of great importance, of equal relevance is the white matter. According to the University of California's Science Today, an apt comparison is this: A computer will not work if its various cables are frayed or broken.
Gray and white matter, so named for the colors they exhibit, both contain what are called axons, which facilitate nerve signals in the brain. Gray matter originates and receives these signals with blood capillaries and nerve cells. White matter facilitates the signals, such as the invisible signal that carries programming from a satellite to a satellite dish as well as the wire that carries that signal from the dish to each television in a home.