Three‐objects‐three‐places test as a screening test for prodromal and mild dementia: validation in a memory clinic population

Abstract

AbstractBackgroundThe Three‐Objects‐Three‐Places (3O3P) test has been developed as a quick screen for episodic memory impairment due to Alzheimer’s Disease (AD). The examiner shows the patient three objects and hides them in three separate places. The patient is later asked what the objects and hiding places were, and which object was hidden where, producing a score out of 9. The aim of this study was to investigate the convergent, discriminant, and diagnostic validity of the test.Method1685 unselected patients from the Geneva Memory Center cohort who underwent the 3O3P test as a screen test in the context of routine assessment were included. The convergent and discriminant validity of the 3O3P test was assessed using an exploratory factor analysis. The known‐group validity was assessed in Cognitively Unimpaired (CU) vs Mild Cognitive Impairment (MCI) and demented using the Area Under the Curve (AUC) and comparing AUCs of the 3O3P test with those of other widely used cognitive tests (MMSE and Delayed recall ‐ DTR). The known‐group validity of the 3O3P was tested also in patients with AD biomarkers.ResultsMean age was 72 years (SD 11.5), 53% were female, mean years of education was 13 (SD 4.4), and mean MMSE was 28.5 (SD 1.5, N = 436) for CU, 25.6 (3.0, N = 767) for MCI and 19.5 (SD 5.2, N = 481). The 3O3P and DTR tests loaded strongly on the same (“memory”) factor, with a saturation of ‐0.89 and ‐0.88 respectively, and weakly on other (“non‐memory”) factors. The 3O3P test can discriminate CU versus MCI with an AUC of 0.71 and versus dementia with an AUC of 0.91. However, MMSE (AUC = 0.83 CU vs MCI; 0.97 CU vs dementia) and DTR (AUC = 0.78 CU vs MCI; 0.93 CU vs dementia) performed significantly better (p<0.001). Patients who were amyloid positive, tau positive, and with significant neurodegeneration achieved lower 3O3P scores.ConclusionThe 3O3P test has demonstrated good convergent and discriminant validity supporting the notion that the test assesses the construct of episodic memory. Although the MMSE and DTR tests generally distinguished between diagnostic groups more effectively, the 3O3P test carries several advantages over these tests, such as its short duration, easy administration, culture‐ and language‐ free nature.