What Causes Diffused Cortical Volume Loss In Brain?

My current brain MRI said I have "DIFFUSE CORTICAL VOLUME LOSS." What could be the reason for this? 10 years ago a brain MRI indicated I have "microvascular white matter disease" -- are these related? I know the problem 10 years ago was caused by Neurontin raising my blood pressure, and once I stopped taking Neurontin my symptoms (brain fog, memory loss) disappeared.