Introduction: Late-onset depression (LOD) has been implicated in
irreversible cognitive decline, potentially mirroring early Alzheimer’s
Disease (AD) pathology. This study aimed to investigate brain activity
differences during an episodic memory (EM) task in LOD patients
compared to healthy controls (HC).
Methods: We recruited 15 LOD patients and 13 HC matched for age
and gender. Participants completed a face-name association task during
functional magnetic resonance imaging (fMRI) focusing on both the
encoding and retrieval phases of EM.
Results: The statistical contrast between the groups revealed that the
HC group showed increased activity in the left visual association cortex
(VAC) and left caudate compared to the LOD group during the encoding
task. During the face recognition task, the HC group showed increased
activity in the right caudate, and during the name recognition task, they
showed increased activity in the right frontal eye field (FEF) compared
to the LOD group.
Conclusion: The differences observed between the HC and LOD groups in
the VAC, caudate, and FEF suggest early changes in maintaining attention,
goal-directed learning, EM formation, and coordination of information
from storage to retrieval before apparent impairment develops in LOD.
Although we did not find statistically significant activations in areas
linked to increased vulnerability to AD, our findings of hypoactivation
in regions responsible for visual processing and attentional orienting in
LOD patients are consistent with hypoactivation patterns observed in AD
patients in previous research. These results enhance our understanding
of the neural mechanisms underlying memory impairments in LOD and
their potential overlap with AD pathology.
Keywords: Alzheimer’s Disease, cognitive dysfunction, episodic memory,
face-name association, late-onset depression, task-based fMRI