What is memory essential for ?

What are the 4 different stages for memory ?

Define Anterograde Amnesia
A loss of the ability to create new memories after the event that caused the amnesia, leading to a partial or complete inability to recall the recent past, while long-term memories from before the event remain intact.
think ‘after the event’
Define retrograde amnesia
A loss of memory-access to events that occurred, or information that was learned, before an injury or the onset of a disease
Appreciate the difference between normal age related memory loss, mild cognitive impairment and dementia

During cognitive screening what is assessed (talking about MMSE etc)