Assessment Of Visuoconstruction Ability In Older Tanzanian Adults: A Pilot Comparison Of The Stick
Design Task And The Benson Figure Copy

Filbert Francis Ilaza1, Grace Anderson Saria2, Aloyce Kisoli3, Ssenku Safic4, Amour Mkubila5, Judith Boshe6, Lachlan Fotheringham7, Annie Killen8, Damasi Mlaki9, Roberta Strasenburgh10, Joseph Bews10, Bernard Mbwele11, Louise Robinson12, Raj Kalaria8, Richard Walker12, Stella Maria Paddick13

Introduction: Dementia remains substantially underdiagnosed in sub Saharan Africa (SSA), partly due to the lack of cognitive screening tools suitable for use across diverse educational and socioeconomic contexts. This study compared the performance of two visuoconstruction tasks, the Benson Figure Copy and the Stick Design Test (SDT) among older adults in rural Tanzania. We hypothesised that the SDT would be applicable regardless of educational attainment, whereas the Benson Figure would be less suitable in this setting.

Methods: Participants aged ≥60 years were recruited from two rural villages in the Hai District of Kilimanjaro, selected to represent highland (Nronga) and lowland (Tindigani) communities with varied socioeconomic and educational backgrounds. Stratified convenience sampling was guided by 2023 census data. Demographic variables included age, sex, literacy, years of education, and occupation.

Results:A total of 131 participants were enrolled (median age 73; 55.7% female). Completion rates were high (SDT: 97.7%; Benson: 86.3%). SDT performance was not significantly associated with sex, age, education, village, visual impairment, or frailty. In contrast, Benson Figure performance was significantly influenced by education (p = 0.007) and showed a trend with frailty. Based on IDEA screening, 13.7% screened positive for dementia. ROC analyses showed similar accuracy for both tasks (SDT AUROC 0.864; Benson AUROC 0.867).

Conclusion: Both visuoconstruction tasks were feasible, and demonstrated good diagnostic accuracy The Benson figure could be completed by most participants.  Although the Benson Figure was marginally more accurate, the SDT’s lack of association with education may mean it remains more widely applicable in SSA.