"Patients with amnestic MCI—who have memory loss as their main symptom and are more likely to develop Alzheimer’s compared to people with non-amnestic MCI—had lower responses to the test, reports the Guardian’s Ian Sample. It can’t directly predict who will develop Alzheimer’s, but it does identify who could be at a higher risk."

It's correlated eith amnestic MCI, ehich itself correlated with higher risk of alzheimers(edit0:typo) (that's what I'm reading from the begining of the paragraph you quoted)