Associations of oddity discrimination task accuracy with perirhinal cortex volume in a multi-ethnic cohort of older adults

Poster Session E - Monday, April 15, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Madeline Wood Alexander^1,2 (madeline.wood@sri.utoronto.ca), Silina Z. Boshmaf¹, Alexander Nyman¹, Rachel Yep¹, Tulip Marawi¹, Isabella J. Sewell¹, Georgia Gopinath¹, Morgan Barense^2,3, Sandra E. Black^1,2, Maged Goubran^1,2, Jennifer S. Rabin^1,2; ¹Sunnybrook Research Institute, Toronto, Canada, ²University of Toronto, Canada, ³Rotman Research Institute, Toronto, Canda

Alzheimer’s disease (AD) neuropathologies (i.e., beta-amyloid, tau) begin to accumulate decades before cognitive symptoms appear. The perirhinal cortex (PRC) is among the earliest brain regions to develop tau. Cognitive tests sensitive to this region could identify individuals at high risk of AD dementia. Tests that minimize language demands and cultural biases are important given North America’s increasing diversity. We investigated whether lower accuracy on an oddity discrimination task predicts reduced PRC volume in ethnically-diverse older adults. This task was chosen given minimal language demands and findings of impaired object discrimination in patients with PRC damage. N=69 adults without dementia (mean age=67.1 years; 66.7% female; 46.4% South Asian; 26.1% East Asian; 23.2% White; 4.3% other ethnicity) from the Canadian Multi-Ethnic Research on Aging (CAMERA) study completed an oddity discrimination task with 3 conditions: familiar objects, unfamiliar objects, and size control. Participants underwent brain MRI, including a high-resolution T2-weighted scan of the medial temporal lobes (MTL). We used the Automatic Segmentation of Hippocampal Subfields pipeline to segment the MTL. Linear models demonstrated a significant association between smaller PRC volume and lower accuracy on the unfamiliar condition (β=0.46, p=.03), but not familiar (β=0.30, p=.22) or size conditions (β= 0.05, p=.83), controlling for age, sex, education, total intracranial volume, and Montreal Cognitive Assessment score. These findings suggest that difficulties discriminating among unfamiliar objects might indicate reduced PRC integrity in a diverse cohort. Future work will examine associations between oddity discrimination and plasma p-tau to confirm whether this task is sensitive to elevated AD risk.

Topic Area: PERCEPTION & ACTION: Development & aging