Difference between "cognition issues", old age and dementia

[EyesWithAFace]

My 88-year old DM has been involved with the mental health team for about 4 years, and has always been told that she has depression/low mood (and prescribed various anti-depressants, none of which helped, although she never stayed on them for more than a few weeks), rather than dementia.
She's got a lot worse mentally over the past 2 years, which we put down to lockdown, a bereavement and declining mobility.
The mental health team have had her on Duloxetine (20-30mg) for about 5 months, and are about to up the dose to 60mg. The 30mg dose doesn't seem to have helped, but apparently that's quite low. Their reasoning is that they want to "treat the depression" to see if there is any underlying depression.

My question is, what is the difference between "poor/declining cognition" and dementia? What degree of declining cognition is just old age?

Alzheimers Ssociety has a useful page on this www.alzheimers.org.uk/about-dementia/symptoms-and-diagnosis/how-dementia-progresses/normal-ageing-vs-dementia

Depression of course messes up your cognition (as do all sorts of other things)

I don't know if you have any interest in looking into this free online course on preventing dementia, but I found it very helpful and informative overall.

It may answer some of your questions about the differences in ageing brains and give some lifestyle tips to improve things with you mother, regardless of her official diagnosis or not.

mooc.utas.edu.au/landing/pd5share

Dementia is a general term for a range of diseases which cause cognitive impairment as one of their main symptoms.

Cognitive impairment can have many causes, some treatable, some curable, some not. Depression can cause reduced cognition, regardless of age, is treatable and the cognitive impairment reversible. If following treatment for depression her cognition does not improve they will test for other causes.

Dementia is marked cognitive decline over a 12 month period; without that decline it’s mild/moderate cognitive difficulties. Conditions like depression can cause cognitive issues so they want that treated before they look at anything else.

To me it was the short term memory loss that brought home to me that my DM had dementia - it wasn’t just old age forgetfulness. Since we’d already been through it with FiL, I just didn’t want to accept it - couldn’t face all that again.

Having always been extremely clued up with finances, she phoned her bank (First Direct) to ask something, and couldn’t remember, literally the instant she put the phone down, what they’d said.
That was when the penny finally dropped, and I don’t mind admitting that my heart sank, too.