Hello Meercat:
We firstly went to the GP to report my husband's severe memory problems plus other confusions. He was ultimately referred to the Mental Health Team, Consultant, and from there he had some tests conducted by a Psychologist. After some 18 mths it was confirmed he had Alzheimers, but following that he had a stroke, so it was changed to Mixed Dementia.
Along the way the CPN (Communithy Psychiatric Nurse) was taking notes on my interpretation of his behaviour.
Are you asking because your Mum has not yet been diagnosed? Is she reluctant to see a GP? That part of it is very hard.