white brain matter

I have someone who is insisting that the white brain mass in her head was caused by a car crash, which she was not injured to any extent.
I've researched white brain matter and as far as I can tell it's cause is from toxins. Have you ever heard of white brain matter developing from a somewhat medium blow to the head causing or a mild concussion injury? - Or even a severe blow to the head. . .and if so how long would it take to show up.
Or would it be correct that white brain matter is caused entirely by unhealthy habits, such as smoking, drinking and extended use of multiple medications.

[lilbit985]

You are supposed to have white brain matter in your head.. Has she had an mri to determine what the "mass" is ?

[Dr Sharma]

Hi there. You are missing somewhere in giving correct information since normal brain comprises white and gray matter both normally. White brain matter is the myelinated portion and grey matter is the unmyelinated matter. Please clarify in a following post as to what your query is. Take care and best regards.