Delayed recall from the primacy portion of a story predicts conversion of patients with mild cognitive impairment to Alzheimer's disease

The serial position effect is a well-established phenomenon characterised by better recall of items at the beginning and end of a list compared to those in the middle. A reduced primacy effect-reflected by diminished recall of items from the initial positions-has frequently been reported in individuals with Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI). This study aimed to examine the serial position curve in the Prose Memory test and to assess whether recall accuracy from the primacy portion of the story can predict progression from MCI to AD. Sixty-two patients diagnosed with MCI were included. After 3 years, 30 patients progressed to AD (cMCI), while 32 remained stable (sMCI). Immediate and delayed recall performance for the three segments of the story (Primacy, Middle and Recency) was analysed. In the immediate recall trial, both MCI groups and healthy controls showed enhanced recall accuracy only for the Primacy portion of the story. In the delayed trial, a reduced primacy effect significantly distinguished cMCI from sMCI patients. Receiver Operating Characteristic (ROC) analysis indicated acceptable diagnostic accuracy of delayed Primacy recall in differentiating converters from stable MCI patients. Delayed Primacy recall in the Prose Memory test predicted conversion from MCI to AD. These results suggest that delayed Primacy recall in prose memory may serve as a non-invasive marker for identifying individuals at risk for AD progression.