Differences in olfactory functional connectivity in early-onset depression and late-onset depression

Ben Chen; Mingfeng Yang; Meiling Liu; Qiang Wang; Huarong Zhou; Min Zhang; Le Hou; Zhangying Wu; Si Zhang; Gaohong Lin; Xiaomei Zhong; Yuping Ning

doi:10.1093/psyrad/kkad030

Differences in olfactory functional connectivity in early-onset depression and late-onset depression

Psychoradiology. 2023 Dec 4:3:kkad030. doi: 10.1093/psyrad/kkad030. eCollection 2023.

Authors

Ben Chen^{1

2}, Mingfeng Yang¹, Meiling Liu¹, Qiang Wang¹, Huarong Zhou¹, Min Zhang¹, Le Hou¹, Zhangying Wu¹, Si Zhang¹, Gaohong Lin¹, Xiaomei Zhong¹, Yuping Ning^{1

3

4

5}

Affiliations

¹ Geriatric Neuroscience Center, The Affiliated Brain Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province 510370, China.
² Smell & Taste Clinic, Department of Otorhinolaryngology, TU Dresden 01307, Germany.
³ The first School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong Province 510515, China.
⁴ Guangdong Engineering Technology Research Center for Translational Medicine of Mental Disorders, Guangzhou 510370, China.
⁵ Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou Medical University, Guangzhou 510370, China.

Abstract

Background: Late-onset depression (LOD) and early-onset depression (EOD) exhibit different pathological mechanisms and clinical phenotypes, including different extents of olfactory dysfunction. However, the brain abnormalities underlying the differences in olfactory dysfunction between EOD and LOD remain unclear.

Objective: The aim of this study was to compare the functional connectivity (FC) patterns of olfactory regions between EOD patients and LOD patients and examine their relationship with cognitive function.

Methods: One hundred and five patients with EOD, 101 patients with LOD and 160 normal controls (NCs) were recruited for the present study. Participants underwent clinical assessment, olfactory testing, cognitive assessments, and magnetic resonance imaging. Eight regions of the primary and secondary olfactory regions were selected to investigate olfactory FC.

Results: Patients with LOD exhibited decreased odor identification (OI) compared with patients with EOD and NCs. The LOD group exhibited decreased FC compared with the EOD and NC groups when primary and secondary olfactory regions were selected as the regions of interest (the piriform cortex, lateral entorhinal cortex, and orbital-frontal cortex). Additionally, these abnormal olfactory FCs were associated with decreased cognitive function scores and OI, and the FC between the left orbital-frontal cortex and left amygdala was a partial mediator of the relationship between global cognitive scores and OI.

Conclusion: Overall, patients with LOD exhibited decreased FC in both the primary and secondary olfactory cortices compared with patients with EOD, and abnormal olfactory FC was associated with OI dysfunction and cognitive impairment. The FC between the orbital-frontal cortex and amygdala mediated the relationship between global cognitive function and OI.

Keywords: MRI; functional connectivity; late-life depression; late-onset depression; olfactory dysfunction; resting-state.