There are three types of memory loss: normal aging, mild cognitive impairment and dementia. Mild cognitive impairment occurs when cognition is lower than expected for age and education. Dementia occurs when cognition declines severely enough to interfere with living independently.
Cognitive impairment can manifest in a variety of ways:
Difficulty with learning new things
Trouble with producing or understanding language
Decreased ability to do complicated tasks
Understanding social cues