Population normative data for three cognitive screening tools for older adults in sub-Saharan Africa.

William Keith Gray,Richard Walker,Catherine Dotchin,Sarah Urasa,Jane Rogathi,Stella-Maria Paddick,John Kissima,Irene Haule,Adesola Ogunniyi,Aloyce Kisoli,Olaide Olakehinde,Akindele Adebiyi,Louise Robinson,Declare Mushi

doi:10.1590/1980-57642021dn15-030005

Abstract

ABSTRACTIn sub-Saharan Africa (SSA),cognitive screening is complicated by both cultural and educational factors, and the existing normative values may not be applicable. The Identification of Dementia in Elderly Africans (IDEA) cognitive screen is a low-literacy measure with good diagnostic accuracy for dementia.Objective: The aim of this study is to report normative values for IDEA and other simple measures [i.e., categorical verbal fluency, the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) 10-word list] in representative community-dwelling older adults in SSA.Methods: Individuals aged ≥60 years resident in 12 representative villages in Kilimanjaro, Tanzania and individuals aged ≥65 years resident within three communities in Akinyele Local Government Area, Oyo State, Nigeria underwent cognitive screening. The normative data were generated by the categories of age, sex, and education.Results: A total of 3,011 people in Tanzania (i.e., 57.3% females and 26.4% uneducated) and 1,117 in Nigeria (i.e., 60.3% females and 64.5% uneducated) were screened. Individuals with higher age, lower education, and female gender obtained lower scores. The 50th decile values for IDEA were 13 (60–64 years) vs. 8/9 (above 85 years), 10–11 uneducated vs. 13 primary educated, and 11/12 in females vs. 13 in males. The normative values for 10-word list delayed recall and categorical verbal fluency varied with education [i.e., delayed recall mean 2.8 [standard deviation (SD) 1.7] uneducated vs. 4.2 (SD 1.2) secondary educated; verbal fluency mean 9.2 (SD 4.8) uneducated vs. 12.2 (SD 4.3) secondary educated], substantially lower than published high-income country values.Conclusions: The cut-off values for commonly used cognitive screening items should be adjusted to suit local normative values, particularly where there are lower levels of education.

Highlights

The prevalence of dementia in older adults living in sub-Saharan Africa (SSA) is considered to be similar to that seen in high-income countries (HICs).[1]
The Community Screening Interview for Dementia (CSI-D) was designed for lower-literacy settings and has been used in urban and rural lowand middle-income country (LMIC) settings worldwide, educational bias is evident when used in some SSA settings, with substantial false-positive rates compared with the DSM criteria for dementia and the prevalence of screen-positive dementia of up to 20%
In Nigeria, 1,132 people were eligible for screening, 15 did not consent, and the data were available for 1,117 people

Summary

Introduction

The prevalence of dementia in older adults living in sub-Saharan Africa (SSA) is considered to be similar to that seen in high-income countries (HICs).[1]. The diagnosis of dementia can be challenging in lowand middle-income country (LMIC) settings, in part due to the lack of validated and locally normed culturally appropriate measures.[2,3,4] Tools developed and normed in other settings have well-recognized limitations when used in SSA, leading to high false-positive rates.[5,6] Educational and cultural differences impact the performance on cognitive screening measures worldwide,[2,7,8] and this impact appears greater in settings where the levels of illiteracy are high among elders. Tools designed for SSA include the Test of Senegal, though this is relatively lengthy and lacks external validation.[13] Tools that are widely used elsewhere such as the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE) appear educationally biased and over-report dementia in low-literacy settings in SSA.[9,10] Most existing SSA epidemiological studies utilize the forms of the Community Screening Interview for Dementia (CSI-D), a fairly lengthy instrument designed to incorporate a cognitive assessment and an informant interview.[1,11] the CSI-D was designed for lower-literacy settings and has been used in urban and rural LMIC settings worldwide, educational bias is evident when used in some SSA settings, with substantial false-positive rates compared with the DSM criteria for dementia and the prevalence of screen-positive dementia of up to 20%.6,12 Tools designed for SSA include the Test of Senegal, though this is relatively lengthy and lacks external validation.[13]

Objectives

Methods

Results

Conclusion