White Matter in the Brain

Think of the brain as a computer system, and it might be easier to understand. According to the UC Davis Health System, the gray matter (nerve cells) of our brain is the computer and the white matter is the cables that connect everything together and transmit signals.

Want more of a biological explanation? White matter is tissue in the brain composed of nerve fibers. The fibers (called axons) connect nerve cells and are covered by myelin (a type of fat). The myelin is what gives white matter its white color.

Myelin speeds up the signals between the cells, enabling the brain cells to quickly send and receive messages. It also provides insulation for the fibers, preventing the brain from short-circuiting. White matter makes up about half of the brain, with gray matter making up the other half.

Some research has found that abnormalities in white matter were present on imaging studies of the brain prior to the development of the symptoms of Alzheimer's disease. Research has also demonstrated the presence of white matter lesions prior to mild cognitive impairment, a condition that carries an increased risk for Alzheimer's disease.

White matter hyperintensities is a term you might hear used to describe spots in the brain that show up on magnetic resonance imaging (MRIs) as bright white areas. According to Charles DeCarli, the director of UC Davis Alzheimer's Disease Center, these areas may indicate some type of injury to the brain, perhaps due to decreased blood flow in that area. The presence of white matter hyperintensities has been correlated with a higher risk of stroke, which can lead to vascular dementia.

White matter hyperintensities are often referred to as white matter disease. Initially, white matter disease was thought to simply be related to aging. However, we now know that there are also other specific risk factors for white matter disease which include high blood pressure, smoking, cardiovascular disease, and high cholesterol. 

Some research has found that physical exercise, in particular, cardiorespiratory activities and weight resistance training, was correlated with improved white matter integrity in the brains of those who participated in those studies.

Physical exercise has also been connected to a decreased risk of dementia as well as a slower cognitive decline in people who already have been diagnosed with Alzheimer's or another kind of dementia.

Other research found that when adults learned new skills, the amount of white matter in their brains increased. This was true for the skills of learning to read as an adult and for learning how to juggle. Additionally, white matter increased relative to the number of hours that professional musicians practiced their instruments.

White matter functioning was also improved by the practice of meditation, and the difference was observed in as little as in two to four weeks.

Historically, science didn't pay as much attention to our brain's white matter as compared to our gray matter. We now know, however, how important white matter is to our overall brain health and cognitive ability, as well as how declines in white matter are correlated with impairments in brain functioning.

If you're looking for that small nudge towards a healthier lifestyle, the research about exercise, mental activity, and meditation may help motivate you toward the reward of improved body and brain health.