This is actually a usable distinction.
"With 10 or 15 minute recall tests already in common use worldwide, we can distinguish individuals who have or are at risk for developing cognitive impairment from healthy adults, and we can do so with better accuracy than any existing tools," said Brainerd.
The notion that memory declines continuously throughout adulthood appears to be incorrect, they say. "When we separated out the cognitively impaired individuals, we found no evidence of further memory declines after the age of 69 in samples of nationally representative older adults and highly educated older adults," said Reyna.
Specifically, the researchers found that declines in reconstructive memory (recalling a word or event by piecing it together from clues about its meaning, for example, recalling that "dog" was presented in a word list by first remembering that household pets were presented in the list) were associated with mild cognitive impairment and Alzheimer's dementia, but not with healthy aging. Declines in recollective memory - recalling a word or event exactly - were a feature of normal aging.