Age and Family History of Alzheimer's Disease and Related Dementias as Predictors of Locus Coeruleus and Salience Network Connectivity

Abstract

The locus coeruleus (LC) is a nucleus on the brainstem that produces the majority of the norepinephrine in the brain. The LC interacts with the salience network (SN), specifically the dorsal anterior cingulate cortex (dACC) and the insula, to coordinate and direct attention. The LC is a site of early Alzheimer's pathology and also experiences normal age-related declines in functioning. In this study, the associations between age, family history of Alzheimer's Disease, and functional connectivity between the LC and key nodes of the SN were explored in a sample of 110 older and younger adults while they completed two different attentionally demanding tasks. Additionally, the relationship between age, family history of Alzheimer's Disease and performance on the cognitive tasks was also examined. The results of this study indicate that age and family history of Alzheimer's Disease and Related Dementias (ADRD) interact to influence level of LC-dACC functional connectivity, but not LC-insula functional connectivity, in the Attention Network Task (ANT), but that neither LC-dACC nor LC-insula functional connectivity were predicted by age and family history of ADRD during the Place Discrimination Task (PDT). Furthermore, age predicted task performance on the PDT, but not on the ANT and family history of ADRD was not associated with performance on either task. These findings suggest that the relationship between family history of ADRD and LC-SN functional connectivity varies based on the region of the salience network examined and the age of the individual.