My mother's dementia has made me wonder about early signs. Three distinct things happened to her about 7 years before her dementia diagnosis. She lost her ability to enjoy reading, and couldn't concentrate even though she had been an avid reader. She lost her sense of smell. Lastly she became so urgent and uptight, a characteristic she always had but to a new extreme. (These all coincided with the beginning of her searching for lost words, and she was about 73 years old). Are any of these things documented early signs?
Loss of smell is a symptom in Alzheimer's, Vascular, and Lewy Body dementia. It may be present in other kinds -- this list is what I happen to have heard of. Loss of concentration is common in dementia, as are agitation and anxiety.
Of course other things can cause these symptoms. Plenty of us develop anxiety without having dementia. The fact that your mother most likely had the beginnings of dementia in her brain seven years ago make it reasonable to speculate whether that was related to the onset of these symptoms.
Much research is now focused on how to recognize the earliest signs of dementia. Research is also urgently looking for ways to treat and even to prevent dementia. Being able to catch it very early will be very valuable when we have better ways to treat it.
Has anyone suggested what type of dementia your mother has?
Is your question mainly a matter of curiosity, or is there a practical reason behind it?