Association Between Hippocampal Volume and African Neuropsychology Memory Tests in Adult Individuals with Probable Alzheimer’s Disease in Democratic Republic of Congo

Article type: Research Article

Authors: Ikanga, Jean^{a; b; *} | Hickle, Sabrina^a | Schwinne, Megan^c | Epenge, Emmanuel^d | Gikelekele, Guy^b | Kavugho, Immaculee^e | Tsengele, Nathan^{b; f} | Samuel, Mampunza^b | Zhao, Liping^g | Qiu, Deqiang^h | Stringer, Anthony^a | Saindane, Amit M.ⁱ | Alonso, Alvaro^c | Drane, Daniel L.^{j; *}

Affiliations: [a] Department of Rehabilitation Medicine, Emory University School of Medicine, Atlanta, GA, USA | [b] Department of Psychiatry, University of Kinshasa and Catholic University of Congo, School of Medicine, Kinshasa, Kinshasa I, Democratic Republic of Congo | [c] Department of Epidemiology, Emory University, Rollins School of Public Health, Atlanta, GA, USA | [d] Department of Neurology, University of Kinshasa, Kinshasa, Kinshasa I, Democratic Republic of Congo | [e] Memory Clinic of Kinshasa, Kinshasa, Kinshasa I, Democratic Republic of Congo | [f] Faculty of Medicine, University of Kikwit, Kinshasa, Democratic Republic of Congo | [g] Department of Biostatistics and Bioinformatics, Emory University, Rollins School of Public Health, Atlanta, GA, USA | [h] Department of Radiology and Imaging Sciences & Department of Biomedical Engineering, Emory University, School of Medicine, Atlanta, GA, USA | [i] Departments of Radiology and Imaging Sciences and Neurosurgery, Emory University, School of Medicine, Atlanta, GA, USA | [j] Departments of Neurology and Pediatrics, Emory University, School of Medicine, Atlanta, GA, USA

Correspondence: [*] Correspondence to: General questions: Jean N. Ikanga, PhD, Department of Rehabilitation Medicine, Emory University, 1441 Clifton Rd NE, Atlanta, GA 30322, USA. Tel.: +1 404 712 5667; E-mail: jikanga@emory.edu and Neuroimaging questions: Daniel L. Drane, PhD, ABPP(CN), Departments of Neurology and Pediatrics, Emory University School of Medicine, Woodruff Memorial Research Building, 101 Woodruff Circle, Suite 6111, Atlanta, GA 30322, USA. Tel.: +1 404 727 2844; E-mail: ddrane@emory.edu.

Abstract: Background:Western studies indicate potential associations between hippocampal volume and memory in the trajectory of Alzheimer’s disease (AD). However, limited availability of neuroimaging technology and neuropsychological tests appropriate for sub-Saharan African (SSA) countries makes it difficult to establish neuroanatomical associations of hippocampus and memory in this locale. Objective:This study examined hippocampal volumes and memory in healthy control (HC) and probable AD groups in the Democratic Republic of Congo (DRC). Methods:Forty-six subjects with probable AD and 29 HC subjects were screened using the Community Instrument for Dementia and the Alzheimer Questionnaire. Participants underwent neuroimaging in Kinshasa, DRC, and memory was evaluated using the African Neuropsychology Battery (ANB). Multiple linear regression was used to determine associations between hippocampal volumes and memory. Results:Patients with probable AD performed significantly worse than HCs on ANB memory measures, and exhibited greater cerebral atrophy, which was significantly pronounced in the medial temporal lobe region (hippocampus, entorhinal cortex). Both AD and HC subjects exhibited high rates of white matter hyperintensities compared to international base rate prevalence, which was significantly worse for probable AD. Both also exhibited elevated rates of microhemorrhages. Regression analysis demonstrated a significant association between hippocampal volume and ANB memory tests. Hippocampal atrophy discriminated probable AD from the HC group. Conclusions:This study establishes the feasibility of conducting neuroimaging research in the SSA, demonstrates many known neuroimaging findings in probable AD patients hold up using culturally appropriate memory tasks, and suggest cardiovascular problems are a greater issue in SSA than in Western countries.

Keywords: African Neuropsychology Battery, Alzheimer’s disease, dementia, hippocampus, magnetic resonance imaging, memory

DOI: 10.3233/JAD-230206

Journal: Journal of Alzheimer's Disease, vol. 96, no. 1, pp. 395-408, 2023