Holly Christian Hunsberger

Sundowning, a common yet poorly understood neuropsychiatric syndrome in Alzheimer’s disease (AD), manifests as evening-specific increases in agitation, confusion, and anxiety. Despite its prevalence and contribution to patient distress, its neural mechanisms remain elusive. Here, we establish a preclinical model of sundowning by characterizing sleep-wake, behavioral, and network-level alterations in an AD mouse model. Aged AD mice exhibit disrupted sleep-wake patterns and reduced slow-wave sleep. Behavioral and pose-tracking analyses revealed motor agitation and a distinct sundowning-like behavioral fingerprint selectively at Sundown. The suprachiasmatic nucleus (SCN) showed disruptions in time-of-day-dependent activation of vasopressin-expressing cells and brain-wide activity-dependent tagging identified hyperconnectivity amongst sensorimotor regions in AD mice at Sundown. Resting-state fMRI data from the Alzheimer’s Disease Neuroimaging Initiative revealed analogous Salience Network alterations in AD subjects. Overall, these cross-species findings define a systems-level framework for sundowning and highlight regions that may be targeted to alleviate a debilitating symptom of AD.

Background: Benzodiazepines (BZDs) are commonly prescribed for anxiety, insomnia, and muscle relaxation, but concerns remain regarding their potential long-term cognitive effects. Prior reviews have reported inconsistent associations between BZD use and cognitive risk, often limited by methodological heterogeneity and unresolved biases. Objective: This systematic review critically evaluates the evidence on BZD exposure and cognitive outcomes, with a specific focus on study design, potential biases, and other factors of methodological heterogeneity. Methods: Following PRISMA 2020 guidelines, we searched PubMed and Google Scholar for studies published between 2010 and 2025. The final search was conducted on 1 July 2025. Eligible studies assessed cognitive performance or incident dementia in community-dwelling adults with regard to BZD use. One reviewer independently screened titles, abstracts, and full texts to determine the eligibility of each study. The other two reviewers participated in the inclusion and exclusion decisions. Any disagreements were resolved by consensus among all three reviewers to minimize bias. No statistical data handling, data conversions, or missing imputation was conducted, as this review did not include quantitative synthesis or meta-analysis. Results: Of 79 references screened by titles, abstracts, and full texts, seventeen articles met the inclusion criteria for this review. Participants in the cohort studies were mostly older adults and cognitively healthy at baseline, while those from case–control studies were dementia patients and their matched controls. Overall, findings remain inconsistent, with five studies reporting an association between BZD use and cognition in the entire cohort, six reporting effects only in specific contexts or subgroups, and six finding no evidence at all. Potential contributing factors to this variability include protopathic bias, operational definitions of BZD exposure, and whether analyses were stratified by factors such as sex, drug half-life, or dose. Conclusions: Due to inconsistencies among findings and limitations in study design rigor, the current review cannot determine whether BZDs independently raise cognitive risk. Future research should adopt more rigorous study designs, with particular attention to addressing protopathic bias, and clarify limitations related to the operational definition of BZD. In addition, our findings support the need for further investigation of BZD association with vulnerable populations, including those with sex-specific susceptibility, low socioeconomic status, and exposure to high-risk prescribing practices.

Background: Our preliminary work revealed earlier anxiety and cognitive decline in female Alzheimer's disease (APP/PS1) mice which correlated to an unbalanced brain‐wide network. To validate these preclinical findings, we analyzed the impact of anxiety on AD in human subjects using the Alzheimer's disease neuroimaging (ADNI) dataset. Our analysis showed that that 1) female AD subjects exhibited higher anxiety; 2) female subjects with amyloid deposition transition to dementia at a faster rate compared to male subjects; 3) female subjects with anxiety have smaller brain volumes; and 4) anxiety is the best predictor of dementia transition. Here, we examine the impact of treating mice with anxiolytics, dissect the circuitry controlling anxiety, and determine whether menopause accelerates AD pathology. Method: Alprazolam (Xanax) was injected 30 minutes prior to a contextual fear memory task in control male and female mice. We then took brain tissue 60 minutes after testing to measure neuronal ensembles activated within the hippocampus. In control and AD (APP/PS1) mice, Cholera Toxin B, was injected into the amygdala and lateral hypothalamus. We measured projections to the ventral hippocampus at 2 and 6 months of age. Lastly, we induced menopause using a chemical, VCD, which depletes ovarian follicles similar to the human transitions. We then ran these mice through a battery of anxiogenic behavior paradigms and examined memory. Result: We found that Alpazolam‐treated male and female mice exhibit a decrease in memory retention, most likely the result of less retrieval cell activation in ventral hippocampus. In mice transitioning through perimenopause we observed earlier anxiety‐like behavior and cognitive decline, but this decline rebounded in postmenopause suggesting a compensatory mechanism. We predict that there will be an increase in the number of projections in ventral hippocampus in female AD mice compared to controls and males. Conclusion: These findings suggest that Neuropsychiatric symptoms impact cognitive decline through sex‐specific pathways in the hippocampus and that benzodiazepines may not be beneficial when treating Alzheimer's disease patients. Menopause can also induce this earlier anxiety‐like phenotype, but the brain may compensate for these hormonal changes. Future studies will examine the impact of chronic BZD use on aging and Alzheimer's disease.

This work brings together the lived experiences of 13 Latinx women in STEM and medicine, who pursued opportunities in the midst of systemic, cultural, and personal barriers. Their autoethnographic stories illustrate how grit, resilience, and community support intersect to shape pathways into science and health care. Collectively, these autoethnographies do more than recount challenges – they illuminate strategies for equity that can inform institutional practices, mentorship design, and national policy.

SUMMARY: Resolving the molecular basis for heterogeneous ageing in the human brain requires integrating its diverse molecular layers. Here we applied a tensor-decomposition framework to jointly analyse single-nucleus RNA-seq, DNA methylation, H3K9ac histone acetylation and proteomic data from 276 post-mortem human cortices. The analysis uncovered two dominant, multi-omic themes. First, we identified an immunometabolic axis characterised by microglial activation, suppression of PI3K-Akt-mTOR signalling and epigenetic signatures that suggest repurposing of developmental transcription factors such as BARHL1. Second, we decomposed the effect of sex into a multi-omic program linked to cellular plasticity: although driven by canonical sex-chromosome genes, this axis was epigenetically enriched for pathways regulating stem-cell pluripotency and exhibited a female-biased shift toward precursor-like states in the oligodendrocyte lineage. Together, these findings deliver a high-resolution atlas of glial ageing and demonstrate that broad risk factors manifest as complex, cell-specific vulnerabilities; an insight critical for the development of targeted therapeutic strategies.

Benzodiazepines (BZDs) are commonly prescribed anxiolytic drugs that act on GABAa receptors, and can result in anterograde amnesia, or the inability to form new memories. While BZDs have been used for decades, the brain regions and neuronal mechanisms responsible for this detrimental side effect are largely unknown at the systems neuroscience level. To analyze the effects of BZDs on long-term memory, activity-dependent ArcCreER^T2 x eYFP mice were injected with Alprazolam 30 min prior to a 3-shock contextual fear conditioning (CFC) procedure and encoding ensembles were tagged with eYFP. Mice were re-exposed to the same context 5 days later, and retrieval cell activation was analyzed using the immediate early gene (IEG), c-Fos, allowing us to determine which brain regions undergo changes after alprazolam injection. Additionally, we address the question of whether alprazolam induces state-dependent memory by altering the timelines of injection. We found that 1) alprazolam treated male and female mice exhibit a decrease in memory retention after conventional CFC and, 2) alprazolam treated female and male mice show a decrease in memory retention in a state dependent CFC timeline with a saline injection prior to re-exposure, 3) alprazolam treated female mice exhibit increased EYFP + (encoding) activation in the dCA1 and enhanced engram activation in the dCA3, and 4) alprazolam treated females showed less c-Fos + activation in the vCA1. These results suggest that alprazolam induces sex-specific ensemble activation throughout the hippocampus and will help us understand the long-term memory deficits associated with BZD use.

Benzodiazepines (BZDs) are commonly prescribed anxiolytic drugs that act on GABAa receptors, and can result in anterograde amnesia, or the inability to form new memories. While BZDs have been used for decades, the brain regions and neuronal mechanisms responsible for this detrimental side effect are largely unknown at the systems neuroscience level. To analyze the effects of BZDs on long-term memory, activity-dependent ArcCreER ^T2 x eYFP mice were injected with Alprazolam 30 minutes prior to a 3-shock contextual fear conditioning (CFC) procedure and encoding ensembles were tagged with eYFP. Mice were re-exposed to the same context 5 days later, and retrieval cell activation was analyzed using the immediate early gene (IEG), c-Fos, allowing us to determine which brain regions undergo changes after alprazolam injection. Additionally, we address the question of whether alprazolam induces state-dependent memory by altering the timelines of injection. We found that 1) alprazolam treated male and female mice exhibit a decrease in memory retention and, 2) alprazolam treated female and male mice show a decrease in memory retention with saline injection prior to re-exposure, 3) alprazolam treated female mice exhibit increased EYFP+ (encoding) activation in the dCA1 and enhanced engram activation in the dCA3, and 4) alprazolam treated females showed less c-Fos+ activation in the vCA1. These results suggest that alprazolam induces sex-specific ensemble activation throughout the hippocampus and will help us understand the long-term memory deficits associated with BZD use.

BACKGROUND: Serotonin (5-HT) receptors and N -methyl-D-aspartate receptors (NMDARs) have both been implicated in the pathophysiology of depression and anxiety disorders. Here, we evaluated whether targeting both receptors through combined dosing of ( R , S )-ketamine, an NMDAR antagonist, and prucalopride, a serotonin type IV receptor (5-HT ₄ R) agonist, would have additive effects, resulting in reductions in stress-induced fear, behavioral despair, and hyponeophagia. METHODS: A single injection of saline (Sal), ( R , S )-ketamine (K), prucalopride (P), or a combined dose of ( R , S )-ketamine and prucalopride (K+P) was administered before or after contextual fear conditioning (CFC) stress in both sexes. Drug efficacy was assayed using the forced swim test (FST), elevated plus maze (EPM), open field (OF), marble burying (MB), and novelty-suppressed feeding (NSF). Patch clamp electrophysiology was used to measure the effects of combined drug on neural activity in hippocampal CA3. c-fos and parvalbumin (PV) expression in the hippocampus (HPC) and medial prefrontal cortex (mPFC) was examined using immunohistochemistry and network analysis. RESULTS: We found that a combination of K+P, given before or after stress, exerted additive effects, compared to either drug alone, in reducing a variety of stress-induced behaviors in both sexes. Combined K+P administration significantly altered c-fos and PV expression and network activity in the HPC and mPFC. CONCLUSIONS: Our results indicate that combined K+P has additive benefits for combating stress-induced pathophysiology, both at the behavioral and neural level. Our findings provide preliminary evidence that future clinical studies using this combined treatment strategy may prove advantageous in protecting against a broader range of stress-induced psychiatric disorders.

Benzodiazepines (BZDs) are anxiolytic drugs that act on GABAa receptors and are used to treat anxiety disorders. However, these drugs come with the detrimental side effect of anterograde amnesia, or the inability to form new memories. In this review we discuss, behavioral paradigms, sex differences and hormonal influences affecting BZD-induced amnesia, molecular manipulations, including the knockout of GABAa receptor subunits, and regional studies utilizing lesion and microinjection techniques targeted to the hippocampus and amygdala. Additionally, the relationship between BZD use and cognitive decline related to Alzheimer’s disease is addressed, as there is a lack of consensus on whether these drugs are involved in inducing or accelerating pathological cognitive deficits. This review aims to inspire new research directions, as there is a gap in knowledge in understanding the cellular and molecular mechanisms behind BZD-induced amnesia. Understanding these mechanisms will allow for the development of alternative treatments and potentially allow BZDs to be used as a novel tool to study Alzheimer’s disease.

INTRODUCTION: Neuropsychiatric symptoms (NPS), such as depression and anxiety, are observed in 90% of Alzheimer’s disease (AD) patients, two-thirds of whom are women. NPS usually manifest long before AD onset creating a therapeutic opportunity. Here, we examined the impact of anxiety on AD progression and the underlying brain-wide neuronal mechanisms. METHODS: To gain mechanistic insight into how anxiety impacts AD progression, we performed a cross-sectional analysis on mood, cognition, and neural activity utilizing the ArcCreER ^T2 x enhanced yellow fluorescent protein (eYFP) x APP/PS1 (AD) mice. The ADNI dataset was used to determine the impact of anxiety on AD progression in human subjects. RESULTS: Female AD mice exhibited anxiety-like behavior and cognitive decline at an earlier age than control (Ctrl) mice and male mice. Brain-wide analysis of c-Fos ⁺ revealed changes in regional correlations and overall network connectivity in AD mice. Sex-specific memory trace changes were observed; female AD mice exhibited impaired memory traces in dorsal CA3 (dCA3), while male AD mice exhibited impaired memory traces in the dorsal dentate gyrus (dDG). In the ADNI dataset, anxiety predicted transition to dementia. Female subjects positive for anxiety and amyloid transitioned more quickly to dementia than male subjects. CONCLUSIONS: While future studies are needed to understand whether anxiety is a predictor, a neuropsychiatric biomarker, or a comorbid symptom that occurs during disease onset, these results suggest that AD network dysfunction is sexually dimorphic, and that personalized medicine may benefit male and female AD patients rather than a one size fits all approach.