Investigations of Memory Monitoring in Individuals With Subjective Cognitive Decline and Amnestic Mild Cognitive Impairment

Background: Subjective cognitive decline (SCD) has been called the prodromal stage of amnestic mild cognitive impairment (aMCI); however, further investigation is needed to confirm this observation. Objective: To define the relationship between SCD and aMCI. Method: In this case-control study, we used the feeling-of-knowing in episodic memory (FOK-EM) test to measure the memory-monitoring function of 40 adults with aMCI, 60 with SCD, and 55 healthy controls. Results: The recognition rates of FOK-EM (53.53% +/- 7.82%; 55.12% +/- 6.08%) and judgment accuracy of the aMCI and SCD groups (gamma values 0.21 +/- 0.11; 0.30 +/- 0.16) were significantly lower than those of the control group (72.32% +/- 5.14%; 0.57 +/- 0.16) (F= 116.24,P< 0.01;F= 128.57,P< 0.01;F= 73.33,P< 0.01). The scores for correct decision/correct recognition (RR; 27.2 +/- 6.43; 29.36 +/- 5.16) and correct decision/false recognition (RF; 30.41 +/- 5.06; 27.26 +/- 4.37) of the aMCI and SCD groups were also significantly lower than those of the control group (49.35 +/- 7.13; 11.16 +/- 4.35) (F-RR= 132.67,P< 0.01;F-RF= 131.8,P< 0.01). Conclusion: Mild clinical impairments in memory-monitoring function may precede clinically confirmed objective memory impairment in individuals with SCD.