At the earliest stages, age-related memory loss and mild cognitive impairment look very similar to dementia. 

Some studies suggest that mild cognitive impairment may actually be early-stage AD.

People with AD have difficulty recalling information after a short period of delay.  New information may be learned, but won’t be remembered after a period of even a few hours.

The current reliance of diagnosis on methods that test memory and mental capacity have epidemiologic implications.  Different rates of diagnosis may be found depending on literacy and education levels.  Cross-cultural diagnostic accuracy is also a concern.