I am so sorry your family must go through this. My 59 yr old husband has had Primary CNS non-hodgkins lymphoma of the brain since April 2006. He has undergone high dose methotrextate chemo, whole brain radiation and temodar. The methotrextate failed after 5 cycles, the whole brain radiation along with temodar put him into complete remission July 2007. He remains in complete remission. If your mom decides to treat, find a neuro-oncologist, not just an oncologist. I can't stress this enough. At this time my husband has not shown any problems with his thinking, no dementia at all. He did have some short term memory problems at the end of radiation treatments but this seems to have vanished. He has had slight problems with motor functions, but this presented at the onset of the tumors, not treatment. Everyone is different and response to treatments will vary from person to person, age, general health at onset and many other individual factors. You are correct this is a rare cancer, not nearly enough information or data is available on it or the treatments. My husband functions well, we have a good quality of life, he is working very hard to increase his walking and working on some balance problems. He is able to get around quite well by himself. So do not give up, treatments can be difficult at times but well worth the end result we have experienced. What treatments are they recommending at this time? If you have questions I will try to help. Good luck to you and your mom.