@roger7 Without more information it is difficult to comment however I would say that on it’s own it would not be a sign of any dementia. Frequent nighttime passing of urine could be the result of a number of physical issues including, if the person is make, prostate issues.
I would suggest discussing the issue with a GP.
My wife has been diagnosed with alzhiemers 4 years ago. This toilet problem is a recent event and just adds to the care she needs
Just wondered if it was a common complaint before seeking help at the health centre