An application study: 21-item Subjective Cognitive Decline Questionnaire in detecting mild cognitive impairment.

Area of Science:

• Neuroscience
• Gerontology
• Psychometrics

Background:

• Subjective Cognitive Decline (SCD) is a prevalent early symptom in Mild Cognitive Impairment (MCI).
• Limited evidence exists on the efficacy of the 21-item SCD Questionnaire (SCD-Q21) in distinguishing MCI from normal cognition (NC).
• The SCD-Q21's utility for early MCI detection in community settings requires further investigation.

Purpose of the Study:

• To evaluate the discriminative performance of the Chinese SCD-Q21 compared to the SCD-Q9 for early MCI detection.
• To assess the added value of demographic and clinical covariates to the SCD-Q21.
• To determine an optimal cut-off score for the SCD-Q21 in identifying MCI.

Main Methods:

• A cross-sectional study involving 294 NCs and 83 individuals with MCI.
• Participants completed the SCD-Q21, SCD-Q9, Hamilton Anxiety Scale (HAMA), and Hamilton Depression Scale (HAMD).
• Logistic regression and Receiver Operating Characteristic (ROC) analyses were employed to assess discrimination and identify optimal cut-offs.

Main Results:

• The SCD-Q21 total scores were significantly higher in the MCI group.
• Lower education, higher Body Mass Index (BMI), and higher SCD-Q21 scores were independently associated with MCI.
• Combined use of SCD-Q21 with covariates (age, sex, education, BMI, HAMA/HAMD) achieved an Area Under the Curve (AUC) of approximately 0.91.

Conclusions:

• The SCD-Q21 offers independent information but has moderate standalone discriminative power for MCI.
• Integrating SCD-Q21 with simple covariates enhances its utility for efficient MCI case-finding in community settings.
• A SCD-Q21 cut-off score of ≥7 demonstrated 69.88% sensitivity and 62.93% specificity.