What is white matter disease? it was on my last ct...mind you ive had over 20 concussions, suffer from severe migraines and memory issues?

You should be evaluated & advised by a neurologist as white matter disease of the brain is often a result of ageing but can occur in multiple sclerosis and also can cause memory issues.

If you have had "over 20 concussions" and "memory issues", you likely have at least some early signs of chronic traumatic encephalopathy from the injuries. Abnormal white matter lesions can be imaged. Migraine on its own, can also cause white matter lesions. The two entities will provide additive areas of "white matter" abnormalities.