Pervasive impairments on hippocampus-dependent memory tasks in major depressive disorder: Role of memory, executive function, and subfield integrity

Poster Session D - Monday, April 15, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Nardeen Yalda^1,2, Mahdieh Varvani Farahani^1,2,3, Georgia Gopinath¹, Darren Liang⁴, Lena Palaniyappan^2,3,5, Amer M. Burhan^6,8, Brian Levine^7,9, Ali Khan^1,2,3, Stefan Kohler^1,2,9; ¹Western University, ²Western Institute for Neuroscience, ³Robarts Research Institute, ⁴Centre for Addiction and Mental Health, ⁵Douglas Mental Health University Institute, ⁶Department of Psychiatry, University of Toronto, ⁷Department of Psychology, University of Toronto, ⁸Ontario Shores for Mental Health Research, ⁹Rotman Research Institute

Previous research suggests that individuals with major depressive disorder (MDD) demonstrate hippocampal (HPC) abnormalities at the level of structure and function, including episodic memory. More recently, there have also been demonstrations of HPC subfield-specific atrophy, generally in CA1, CA3, and dentate gyrus subregions. Typically, abnormalities in subfield-structure and function have been examined in isolation. In the present study, we tested performance on hippocampus-dependent memory tasks alongside subfield-specific integrity of HPC structure in a sample of patients (N = 24) with clinically diagnosed treatment-resistant depression. Assessments included behavioral pattern separation, pattern completion, autobiographical memory, memory for face-name associations, and neuropsychological tests of executive functioning, in combination with surface-based estimation of subfield-specific atrophy derived from high-resolution structural MRI. As compared to matched control participants (N = 20), patients exhibited impaired recall from episodic autobiographical memory, irrespective of the age of memories. Patients also demonstrated impaired recognition performance on tests of pattern separation, face-name associations, and pattern completion. These behavioural deficits in patients were observed alongside significantly reduced volume in the left dentate gyrus, left CA3, and right CA1 regions. MDD often also results in impairments in executive control, which can influence memory performance. In the present sample, neuropsychological markers of executive-function were positively related to discrimination performance for previously learned items and associations across several tasks. Our findings reveal pervasive impairments on tasks tapping into multiple functions that depend on HPC integrity. They also highlight a role for executive function deficits on tasks that are typically considered HPC-dependent.

Topic Area: LONG-TERM MEMORY: Episodic