What is the white matter?

White matter describes the deep regions of the brain that contain the axons or "wiring" of the brain, connecting different areas of the brain and allowing for normal cognitive function.



White matter hyperintensities, image from Wardlaw et al, 2015, DOI: 10.1161/JAHA.114.001140.

What are the white matter hyperintensities?

White matter hyperintensities (WMHs) are frequently seen on MRI scans of the brain in older people. These lesions are common in MRIs of asymptomatic individuals, and their prevalence increases with age from approximately 10% to 20% in those approximately 60 years old to close to 100% in those older than 90 years. Certain MRI scan sequences can reveal white matter hyperintensities seen as bright signals in otherwise dark brain tissue.  The below images show a range of less severe (left) to severe white matter disease (right).

What is the cause of white matter hyperintensities?

WMHs are a manifestation of small vessel disease. This means that the smaller blood vessels located in the brain are affected. The lesions are reflecting chronically reduced blood flow in deep areas of the brain. 


These abnormalities may be caused by different conditions as risk factors including:

  • Aging

  • Hypertension

  • Diabetes

  • Smoking

  • Elevated cholesterol

  • Heart failure

  • Congenital factors

  • Neurodegeneration (as in Alzheimer's disease)

What is the clinical significance of white matter hyperintensities?

Even though these changes are common for many people, the presence in the white matter is a predictor of a future risk of stroke, decline in global cognitive performance and executive function, dementia (Alzheimer type, vascular, and mixed); and death, particularly due to cardiovascular causes.

What is the next step after my neurologist found white matter hyperintensities in my MRI?

The main indication once the white matter hyperintensities have been detected is to control the contributing risk factors. The treatment includes:

  • Control of hypertension

  • Control of diabetes mellitus

  • Control of cholesterol

  • Exercise

  • Healthy diet

  • Stop cigarette smoking

  • Avoidance of further brain injury