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

Area of Science:

• Neurology
• Geriatrics
• Public Health

Background:

• Cognitive screening in sub-Saharan Africa (SSA) is challenged by cultural and educational factors.
• Existing normative values for cognitive tests may not be applicable in SSA populations.
• The Identification of Dementia in Elderly Africans (IDEA) cognitive screen is a validated low-literacy tool for dementia detection.

Purpose of the Study:

• To establish normative values for the IDEA cognitive screen and other simple cognitive measures in community-dwelling older adults in SSA.
• To assess the influence of age, sex, and education on cognitive performance in SSA.
• To provide a basis for adjusting cognitive screening cut-offs in SSA.

Main Methods:

• Cognitive screening of 3,011 individuals in Tanzania (≥60 years) and 1,117 in Nigeria (≥65 years).
• Normative data were stratified by age, sex, and education.
• Included the IDEA cognitive screen, categorical verbal fluency, and the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) 10-word list.

Main Results:

• Lower cognitive scores were observed with increasing age, lower education, and female gender.
• 50th decile IDEA values ranged from 8/9 (≥85 years) to 13 (60-64 years), and were lower for uneducated and female participants.
• Normative values for verbal fluency and word list recall were substantially lower in uneducated individuals compared to those with secondary education and lower than high-income country values.

Conclusions:

• Cognitive screening cut-off values require adjustment for local normative data in SSA.
• Lower educational attainment significantly impacts cognitive test performance.
• These findings are crucial for accurate dementia diagnosis in SSA populations.