Atrophy links lower novelty-related locus coeruleus connectivity to cognitive decline in preclinical AD.

INTRODUCTION: Animal research has shown that tau pathology in the locus coeruleus (LC) is associated with reduced norepinephrine signaling, lower projection density to the medial temporal lobe (MTL), atrophy, and cognitive impairment. We investigated the contribution of LC-MTL functional connectivity (FCLC-MTL) on cortical atrophy across Braak stage regions and its impact on cognition. METHODS: We analyzed functional magnetic resonance imaging and amyloid beta (Aß) positron emission tomography data from 128 cognitively normal participants, associating novelty-related FCLC-MTL with longitudinal atrophy and cognition with and without Aß moderation. RESULTS: Cross-sectionally, lower FCLC-MTL was associated with atrophy in Braak stage II regions. Longitudinally, atrophy in Braak stage 2 to 4 regions related to lower baseline FCLC-MTL at elevated levels of Aß, but not to other regions. Atrophy in Braak stage 2 regions mediated the relation between FCLC-MTL and subsequent cognitive decline. DISCUSSION: FCLC-MTL is implicated in Aß-related cortical atrophy, suggesting that LC-MTL connectivity could confer neuroprotective effects in preclinical AD. HIGHLIGHTS: Novelty-related functional magnetic resonance imaging (fMRI) LC-medial temporal lobe (MTL) connectivity links to longitudinal Aß-dependent atrophy. This relationship extended to higher Braak stage regions with increasing Aß burden. Longitudinal MTL atrophy mediated the LC-MTL connectivity-cognition relationship. Our findings mirror the animal data on MTL atrophy following NE signal dysfunction.

Changes in Apathy, Depression, and Anxiety in Parkinson's Disease from before to during the COVID-19 Era.

Apathy, depression, and anxiety are common non-motor symptoms of Parkinson's disease (PD). Tracking the changes in such symptoms over time would be valuable not only to determine their natural course during the disease, but also to establish the effects of unusual historical events interacting with the natural course. Having collected data on apathy (Apathy Scale), depression (Beck Depression Inventory-II), and anxiety (Parkinson's Anxiety Scale) in a large sample of persons with PD (PwPD) before the beginning of the COVID-19 era, we followed up with these individuals to investigate the changes in their prevalence of apathy, depression, and anxiety across two timepoints (T1 and T2). Of the original 347 participants, 111 responded and provided complete data at T2. The data collection at T1, before COVID-19, occurred between 2017-2018. The data collection at T2 occurred in 2021 and included the same measures, with the addition of the Coronavirus Impact Scale to assess the effects of the pandemic on the individual participants. Over this period, there was a significant increase in apathy, but not in depression or anxiety. Anxiety and depression, but not apathy, were correlated with the impact of COVID-19.