Is vascular dementia progressive like Alzheimers?

My 87 yr. old mother is bedridden due to spinal stenosis. While in rehab a few months ago she started to experience cognitive impairment which we are now being told is vascular dementia. As far as we know my mother has not had a stroke. I am wondering if Spinal Stenosis can cause vascular dementia. I am also wondering what to expect in terms of progression. Currently my Mom has some trouble finding words but is most often quite pleasant and very much aware of what is going on around her.