Altered functional connectivity of the locus coeruleus in Alzheimer's disease patients with depression symptoms.

Studies have shown that functional abnormalities in the locus coeruleus (LC) are strongly associated with depressive symptoms, but the pattern of LC functional connectivity in Alzheimer's disease patients with depressive symptoms (D-AD) remains unclear. The current study aimed to investigate the characteristics of LC functional connectivity (FC) in D-AD using resting-state functional magnetic resonance imaging (rsfMRI). We obtained rsfMRI data in 24 D-AD patients (aged 66–76 years), 14 non-depressive AD patients (nD-AD) (aged 69–79 years) and 20 normal controls (aged 67–74 years) using a 3 T scanner. We used the FC approach to investigate abnormalities in the LC brain network of D-AD patients. One-way ANCOVA and post-hoc two-sample t -tests were performed to compare the strength of functional connectivity from the LC among the three groups. Our results showed that, compared with normal controls, D-AD showed decreased left LC FC with the right caudate and left fusiform gyrus, whereas nD-AD showed decreased left LC FC with the right caudate, right middle frontal gyrus and left fusiform gyrus. Compared to nD-AD, D-AD showed increased left LC FC with right superior frontal gyrus and right precentral gyrus. These findings contribute to our understanding of the neural mechanisms of D-AD. • The locus coeruleus is the main nucleus for the synthesis of the neurotransmitters norepinephrine and dopamine in the brain. • The current study investigates the brain network of the locus coeruleus in depressed Alzheimer's patients. • The differential brain regions are located in the caudate, middle frontal gyrus, precentral gyrus and fusiform gyrus. • These findings contribute to our understanding of the neural mechanisms in depressed AD patients. [ABSTRACT FROM AUTHOR]