The intrinsic locus coeruleus functional connectivity change in older adults with subjective memory complaint

Abstract

AbstractBackgroundThe locus coeruleus (LC) is critical for late‐lift cognitive processing by modulating the norepinephrine system, which is often the first place Alzheimer’s pathology appears. Previous researches have identified that the LC was associated with late‐life cognitive ability. This study aims to investigate whether the intrinsic LC functional connectivity (LC‐FC) is altered in older adults with subjective memory complaints (SMC).MethodA total of 199 participants were selected from the Alzheimer’s Disease Neuroimaging Initiative database, including 95 SMC older adults and 104 cognitively normal individuals (CN). Bilateral LCs were selected to construct the LC functional connectivity based on resting‐state fMRI data. The cognitive function was evaluated by using the ADNI composite executive function (ADNI‐EF) and memory (ADNI‐Mem) scores at baseline and 24 months later. Data were analyzed using the voxel‐wise two‐sample t‐test and partial correlation analysis, we utilized permutation testing with threshold‐free cluster enhancement (TFCE) to multiple comparison correction.ResultThere were no significant differences in demographic information and cognitive function between the two groups. In the left LC‐FC network, compared to CN group, the SMC group showed increased LC‐FC in the left salient network (anterior insula, and frontal operculum cortex), hippocampus, and right default mode network(DMN, inferior temporal gyrus), while they had decreased LC‐FC in left inferior temporal gyrus. No significant difference in the right LC‐FC network between the two groups. The altered FC between left LC and right inferior temporal gyrus (DMN) was significantly associated with ADNI‐EF performance in the SMC group, controlled the effect of age, gender, and APOE genotype (r = ‐0.404, p = 0.002), and the FC between LC and right ITG was also associated with executive function performance after 24 months in SMC group.ConclusionThe present study manifested the abnormal intrinsic LC functional connectivity in elder adults with SMC. In addition, the FC between LC and default mode network was associated with the executive function performance in SMC. These findings might suggest an LC norepinephrine system compensatory mechanism in cognitive processing in older individuals with SMC.