Three-Objects-Three-Places Episodic Memory Test to Screen Mild Cognitive Impairment and Mild Dementia: Validation in a Memory Clinic Population

Abstract

Background

The Three-Objects-Three-Places (3O3P) test is a 5-min screen for episodic memory impairment due to Alzheimer's disease, known for its briefness and easy administration, culture- and language-free nature, and the absence of specific equipment. However, no studies have validated its potential in memory clinic cohorts. The aim of this study was to test its convergent, discriminant, and known-group validities and to define thresholds for its clinical use.

Methods

We included 2062 cognitively unimpaired (CU), mild cognitive impairment (MCI) and dementia patients from the Geneva Memory Center cohort who underwent the 3O3P test in the context of clinical practice. Convergent and discriminant validities were assessed using an exploratory factor analysis. The known-group validity was assessed in CU vs. MCI and dementia using the area under the curve (AUC). 3O3P test scores vs. amyloid and tau positivity, neurodegeneration, and cognition (ATNC) were assessed using the Kruskal-Wallis test. The 3O3P test cut-offs were calculated using sensitivity, specificity, PPV, NPV, and accuracy.

Results

Mean age was 72 years (SD = 11), 60% were female, mean education was 13 years (SD = 4), and mean MMSE was 25 (SD = 5). The 3O3P and Delayed Total Recall tests loaded strongly on the “memory” factor and weakly on “non-memory” factors. The 3O3P test can discriminate CU vs. MCI (AUC = 0.71) and dementia (AUC = 0.92). Higher 3O3P scores were associated with lower prevalence of ATNC (p < 0.001). A 3O3P value of 7 can detect MCI and dementia patients.

Conclusions

The 3O3P test has demonstrated good convergent, discriminant, and known-group validity in a large memory clinic population.