Could A Low Sodium Cause Senility And Loss Of Memory?

My father is in the hospital, 83 yo male, with symptoms including: confusion, doesn t know where he is one minute, but does the next; and doesn t know what year it is or finish his sentences, although he was very clear thinking about a month ago; chronic low sodium, ICP of 19, larger then normal pockets of fluid in his ventricles from CT scan and MRI; high blood pressure 180-200 over 80ish that is hard to control without an IV drip of bp meds; incontinence and frequent urge to urinate, low back pain, and tiredness and lack of balance. His sodium is currently around 124- but was as low as 120 about 2 weeks ago. We got the sodium level up to 135 pushing 2 to 3.5g of sodium a day, but it fell back down to 124 in about 4 days in the hospital. This was a man that was able to walk, drive a car and think fairly clearly with a very good memory about 4 to 6 weeks ago, and then things went down hill very quickly. He was brought into the ER last sat night and diagnosed as having a stroke, so transported from a rual hospital to another hospital in a major city. Further CT scans and an MRI show no evidence of a stoke and the DR s feel that Cranial fluid flow doesn t show any evidence of NPH either. The DRs did a lumbar puncture or spinal tap, but only pulled out 24 ccs so were not looking for NPH, just pulling fluid to test for infection. Just after the spinal tap, the nurse was able to ask my farther where he was, and he answered clearly and with the correct answer, but then began to fade again a little while later. No infections in Spinal fluid or urine have been detected yet. My farther is still unclear and unable to care for himself and they are looking to send him home to hope he just gets better on his own. They have the blood pressure stabilized for now, under 170 over 80 with oral meds, but need it taken ofter to check for elevated BP. Before he went into the hospital he had been complaining of being cold and unable to get or keep his feet warm. He had multiple pairs of socks on and used a heating pad for his feet even though it was clost to 80 degrees. His appetite has been OK, but fails towards the end of the day. He appeared fairly depressed and adjatated a lot of the time and doesn t quite understand that we are at the hospital or why some of the time. He will say, well why don t we get ready and go out for dinner, and then get angry and snap at his wife when she says he has to stay, this anger is also unlike him. We are concerned that there is no root problem diagnosed other then a, fragile brain, and a, multi-faceted disorder, and would appreicate any ideas anyone has on why this could be happening. The true senility (unable to tell us the date or year) came on very quickly (within the last few weeks) but memory lapses and feelings of uncertainty may have been around for about 2 months prior. The inability to walk is just the last few weeks, before that he didn t need a walking or anything and walked fairly well. The incontinence was mostly at night and has just been the last 2-3 weeks. In response to low sodium (thought to be the sole original cause of this) we had reduced one BP med (clonidine) in half - this has since been removed in the hospital and replaced with another BP drug and we cut in half (3 weeks ago) and later removed (10 days ago) a diuretic (Torasemide) per instruction of Dr s in his hometown.