Hippocampal and medial temporal lobe structure atrophy is commonly observed in patients with mild neurocognitive disorders and dementias of various neurodegenerative conditions, with the degree of atrophy in these regions correlating with cognitive performance on memory tasks. This research has been conducted largely in western and educated countries. As cognitive aging, risk factors, clinical course, and neuropathology can differ between individuals of different races and ethnicities, our goal is to determine whether these findings also generalize to patients with suspected dementias living in the Democratic Republic of the Congo (DRC).

Neuroimaging and cognitive data have been collected on 40 subjects with probable dementia from the DRC and 40 age-, education-, and gender-matched controls. Patients were classified into groups based on scores on the Community Screening Instrument and the Alzheimer's Questionnaire. All participants completed the African Neuropsychological Battery. T1 MPRAGE images were acquired on Siemens 1.5T scanner. Freesurfer was used to derive volumes and cortical thickness of medial temporal lobe regions. Volumes of structures were divided by intracranial vault volumes to adjust for head size. T-tests were used to compare hippocampal volumes, entorhinal cortex thickness, and perirhinal cortex thickness between subjects with probable dementia compared to healthy age-, gender-, and education-matched controls. Bivariate correlations were conducted to determine whether the volumes of these structures correlate significantly with learning and memory measures on the ANB.

Results will be determined by the methods described previously.

Results from this study will demonstrate whether structural brain changes commonly seen in individuals with dementia living in western and educated countries also are observed in the DRC. Results will also demonstrate whether these brain changes coincide with the degree of impairments on tasks of memory, and whether these structures can be used to aid in clinical diagnosis of patients with dementia and support the use of the ANB and neuroimaging in clinical detection of dementias in the DRC.

Using the African Neuropsychology Battery (ANB), we seek to develop normative data by examining the demographic effects for two learning process scores: initial learning (Trial One) and learning ratio (LR, the percentage of items learned relative of to-be-learned material following Trial 1).

Healthy participants from the Democratic Republic of Congo completed the four memory tests of the ANB: the African Story Memory Test (ASMT), African List Memory Test (ALMT), African Visuospatial Memory Test (AVMT), and African Contextual Visuospatial Memory Test (ACVMT). We developed indices of learning for each subtest, as well as aggregate learning indices for Trial 1 and LR, and composite indices examining verbal, visual, contextual, and noncontextual learning, and grand indices comprising all four subtests.

Trial 1 and LR scores each demonstrated acceptable intercorrelations across memory tests. We present normative data for Trial 1 and LR by age and education.

These data provide normative standards for evaluating learning in Sub-Saharan Africa.