Journal of Neurogenetics

Objectives: To determine whether distinct anxiety phenotypes (rumination, global anxiety and worry; RAW) are associated with plasma brain-derived (BD) phosphorylated-tau (p-tau) biomarkers of Alzheimer's disease (AD) in older adults. Design: Cross-sectional observational study. Methods: Participants were 89 older adults aged 50[≥]years (mean age 64.3{+/-}8.8 years) enrolled in the RAW Brain study (R01 MH108509) in Pittsburgh, Pennsylvania. Anxiety phenotypes were assessed using the Penn State Worry Questionnaire (PWSQ[≥]50), Rumination Subscale from the Response Style Questionnaire (RSQ>50), and Hamilton Anxiety Rating Scale (HARS>17). Participants were classified as High-RAW if they exceeded established severity thresholds on [≥]1 domain; continuous anxiety scores were used for primary analyses. Plasma BD-tau, BD-p-tau181, BD-p-tau217, and BD-p-tau231, and matched non-BD versions were quantified using the NULISAseq CNS Panel. Associations between anxiety phenotypes and tau biomarkers were examined using multivariable linear regression adjusted for age, sex, and APOE4 status, with Benjamini-Hochberg false discovery rate correction. Results: Greater global anxiety was associated with higher plasma BD-p-tau181 ({beta}=0.308, 95% CI [0.003,0.048], p=0.047). This association was also observed categorically (adjusted Cohen's d=0.462, p=0.049). Worry and rumination were not associated with BD-p-tau181, and no anxiety phenotypes were associated with BD-tau, BD-p-tau217, BD-p-tau231, or corresponding non-BD alternatives. Conclusions: Greater late-life global anxiety, but not worry or rumination, was selectively associated with higher plasma BD-p-tau181. These findings extend epidemiologic evidence linking anxiety to AD risk by identifying a biologically specific blood-based correlate linking anxiety with AD-related p-tau biology. Longitudinal studies incorporating amyloid and tau biomarker confirmation are needed to determine whether anxiety precedes, accompanies, or results from early AD pathophysiology.

Importance: Anxiety phenotypes - rumination, global anxiety, and worry (RAW) - are increasingly associated with Alzheimer's disease and related dementias (ADRD) risk, yet how anxiety phenotypes relate to coordinated, multi-system biology in the at-risk older adults is unknown. Objective: To map associations between anxiety phenotypes and plasma proteomic profile across five ADRD-relevant biological domains in older adults with high anxiety symptoms. Design, Setting, and Participants: Cross-sectional analysis of 110 older adults (aged 53-75 years) without dementia from the observational longitudinal RAW Brain study in Pittsburgh, Pennsylvania. Main Outcome(s) and Measure(s): Plasma was profiled with the NULISAseq CNS panel. Principal component (PC) analysis was conducted with Horn's parallel analyses across five ADRD-relevant biological domains (amyloid/tau pathology, inflammation, neurodegeneration, synuclein/synaptic disorders, and vascular) yielded 14 PCs (37.4-64.9% within-domain variance). Associations with each phenotype were tested by linear regression adjusted for age and sex, with Benjamini-Hochberg false discovery rate correction (p-FDR<0.05). Results: A neurodegeneration component (higher neuronal pentraxins and neurofilament light, with lower neurogranin) was associated with all three phenotypes (rumination, {beta} =0.26; global anxiety, {beta}= 0.39; worry, {beta} =0.36; all p-FDR<0.05). Inflammatory, VEGF receptor-ligand, and phospho-tau versus amyloid-processing components showed phenotype-specific associations, most often with worry severity. Conclusion and Relevance: Distinct anxiety phenotypes map onto dissociable plasma proteomic profiling, converging on a shared neurodegeneration axis reflecting neuronal injury, while diverging across neuroimmune, vascular, and proteostatic domains. These results point toward the biological heterogeneity of anxiety phenotypes as risk factors for ADRD. Further research is needed to clarify these biological pathways and explore targeted prevention strategies.

Objectives: Subjective word-finding complaints (SWFC) are among the most frequent cognitive complaints in cognitively unimpaired older adults (CU). However, no comprehensive tools currently exist to assess this phenomenon. This study aimed to conduct a preliminary psychometric evaluation of a novel SWFC questionnaire, better characterize SWFC, and establish their demographic/clinical correlates. Methods: 287 older adults (192 CU, 95 with mild cognitive impairment (MCI)) from the PREVENT-AD cohort completed a novel 29-item SWFC questionnaire available in French and English. Internal consistency and construct validity were evaluated. Relationships of demographic/clinical variables with total and domain-specific SWFC scores were analyzed. Results: Internal consistency was strong (Cronbach's Alpha=0.926). Difficulty remembering the names of famous people was the most frequently endorsed item (83%), whereas items related to the social impacts of SWFC were least frequently endorsed. Exploratory factor analysis revealed six distinct factors: SWFC coping strategies, fluency difficulties and affective impacts, SWFC-related errors, proper noun retrieval difficulties, social impacts of SWFC, and common noun retrieval difficulties. Older age was associated with higher total SWFC and greater proper and common noun retrieval difficulties, female sex with greater proper noun retrieval difficulties, higher education with lesser social impacts of SWFC, and MCI status with greater social impacts of SWFC. Discussion: These findings demonstrate that SWFC are multidimensional rather than a unitary construct in aging. This novel questionnaire provides a promising tool for characterizing the type and severity of specific SWFC and may facilitate future research examining which complaint profiles are associated with adverse clinical outcomes, including Alzheimer's disease.

Sleep health reflects interacting demographic, clinical, micro- and macroarchitectural, and neurophysiological factors that may not be captured by single metrics or diagnostic categories. We applied hierarchical clustering to longitudinal Sleep Heart Health Study data from 1,468 adults with complete polysomnographic, demographic/clinical, and pre-sleep electroencephalographic data at two visits separated by 5.19 {+/-} 0.27 years. Forty nonredundant features selected from candidate demographic/clinical, sleep-stage, and pre-sleep spectral measures were clustered independently at each visit. Four reproducible sleep-health phenotypes emerged: a group with preserved deep sleep and favorable mental-health ratings; a large light-sleep group with low N3 and high N1; an older, physically unhealthy group with shorter total and rapid-eye-movement sleep; and a younger, physically healthy group with longer total and rapid-eye-movement sleep. The same population-level structure was evident at both visits, although only 37.7% of participants retained the same cluster assignment, with transitions most directed toward the light-sleep phenotype. An independent analysis of slow-wave morphology, excluded from cluster construction, differentiated all four phenotypes after false-discovery-rate correction. Groups with preserved or healthier sleep showed more numerous, higher-amplitude, steeper, and shorter slow waves, whereas the light-sleep and physically unhealthy groups showed weaker and more prolonged slow waves. Pre-sleep spectral features did not differ significantly across clusters after correction. These findings identify reproducible but individually dynamic sleep-health phenotypes and demonstrate that macro-architectural cluster structure is reflected in independent measures of NREM sleep microarchitecture.

Transgenic GAL4 lines are widely used in Drosophila to label and manipulate specific cell types, but the resulting reporter expression patterns do not always represent ongoing driver activity. We generated a collection of neuropeptide T2A-GAL4 knock-ins and characterized their expression by native-fluorescence imaging using UAS-CD8::GFP and a Brp-miRFP680 knock-in, eliminating the need for immunostaining. During characterization of these lines, we observed cases in which adult GFP patterns did not match the on-going GAL4 activity, as well as cases in which GAL4 produced adverse cellular effects. Using temperature-sensitive GAL80, we found that adult GFP expression in certain neurons driven by CCHa2-T2A-GAL4 and Dsk-T2A-GAL4 depended on GAL4 activity before eclosion and was not reproduced by adult-only induction. Several GAL4 lines also showed dominant developmental phenotypes. Heterozygous Burs-T2A-GAL4 animals, for example, displayed wing-expansion defects that were fully suppressed by GAL80. Severe wing defects were not accompanied by a reduction in the number of reporter-labeled neurons before eclosion, but the morphology of these neurons were affected. These observations illustrate how developmental driver history and GAL4-associated cellular effects can influence reporter patterns in the adult nervous system.

The sexual identity of specific tissues can be altered through cell-autonomous manipulation of the sex determination pathway in the nematode Caenorhabditis elegans. Previously described sexually mosaic strains carried multicopy transgenic arrays that are potentially subject to transgene silencing or misexpression artefacts. We used here the CRISPR/Cas9 system to engineer strains in which coding sequences for either a masculinizing agent (FEM-3) or a feminizing agent (intracellular domain of TRA-2) are inserted with a trans-splicing system at the 3 end of endogenous genetic loci that are known to be expressed in either a neuron-specific (rab-3) or gut-specific (elt-2) manner. We validate the tissue-specific sex-transformations induced by these genomic manipulations through expression analysis of known sex-specific genes and through assaying behavioral readouts. These strains may serve the worm community as standard reference tools to study the consequences of tissue-specific sex transformations.

Drosophila s-LNv clock neurons promote nighttime sleep by releasing the neuropeptide sNPF to activate sNPF receptors (sNPF-Rs) on l-LNv clock neurons. Behavior is controlled by synaptic transmission, but s-LNv and l-LNv neurons are not connected directly by chemical synapses. To investigate the basis of sNPF/sNPF-R communication between LNv neurons, the spread of sNPF was imaged in the adult brain. We report the daily midmorning burst of sNPF released from s-LNv terminals does not reach l-LNv neurons or s-LNv somata. Instead, sNPF released by the s-LNv soma late at night in response to sleep-promoting IP3 signaling reaches l-LNv somata, but not their terminals. In addition to communication by neuropeptide diffusion, analysis of fly connectomes revealed that adult s-LNv and l-LNv neurons form non-synaptic direct contacts mediated by cytonemes. Remarkably, genetically perturbing LNv neuron cytonemes alters sleep latency, but not nighttime sleep, the target of somatic sNPF release, or circadian behavior, which depends on PDF neuropeptide released by LNv terminals. Therefore, three distinct aspects of adult rhythmic behavior are produced by terminals, the soma and cytonemes, with the latter possibly acting via contacts that are not currently annotated in the connectome.

In many insects, females exhibit behavioral changes after mating. This plasticity can be mediated by interactions between male-derived seminal fluid proteins (SFPs) and the female nervous system. The Drosophila melanogaster seminal fluid protein Sex Peptide (SP) causes mated females to sleep less during the day and consume more food than unmated females, among other behavioral changes. Although the SP-sensing neural circuits that convey information to the females brain are known, the downstream neurons that affect post-mating behaviors remain unknown. P2 neurons in the flys central brain are good candidates for regulating post-mating changes in sleep and food consumption, as they express feeding- and sleep-responsive neuropeptide F (NPF), directly innervate the flys sleep center (the dorsal fan-shaped body, dFB), and are responsible for social-isolation-induced changes in sleep and food consumption. Using the GAL4/UAS system, we activated or silenced P2 neurons in mated and unmated females. We measured sleep duration using Drosophila Activity Monitors (DAM) and food consumption using Capillary Feeder (CAFE) and blue-dye assays. We found that P2-neurons are not responsible for post-mating changes in sleep and food consumption: mated females slept less during the day and ate more compared to unmated females irrespective of P2 neuron perturbation. Together, these results indicate that P2 neurons are unlikely to be primary downstream neurons through which male-transferred SP regulates post-mating sleep and food consumption. Future studies could determine whether P2 neurons regulate other post-mating behaviors or modulate sleep and feeding behaviors in a context-dependent manner.

Early identification of cognitive impairment remains challenging in settings where comprehensive cognitive and clinical assessments are not available. Acoustic and linguistic features in naturalistic speech may serve as useful behavioural markers of cognitive impairment, but the value of integrating these measures with cognitive assessment remains unclear. We tested whether combining acoustic and linguistic features from one-minute speech samples with multi-domain cognitive assessment (spanning attention, language, memory and executive functions) improves classification of cognitively unimpaired individuals from those with amnestic mild cognitive impairment or early-stage Alzheimer's Disease. Across multiple machine learning models, combining cognitive, acoustic and linguistic features yielded significantly better classification performance than models using cognitive or speech features alone (area under the curve = 0.96-0.98, both comparisons p < .05). This proof-of-concept study reveals that integrating speech-based measures with cognitive testing may improve identification of cognitive impairment, supporting the development of accessible and scalable multimodal screening tools for primary care.

Objectives: The rising prevalence of financial exploitation among older adults has prompted research on the cognitive mechanisms underlying financial decision making in later life. Prior work has demonstrated a link between cognitive impairment and financial vulnerability. The present study examined the unique contributions of composite measures of memory and executive functioning to scam susceptibility in middle-aged to older adults without dementia. Methods: One hundred and fifty-one participants (age= 68.2 {+/-} 8.0 years, 72.2% female, years of education= 16.4 {+/-} 2.2) completed standard neuropsychological measures from the Uniform Data Set (UDS), Version 3, and the California Verbal Learning Test, Second Edition, and a self-report scam susceptibility measure. Psychometrically robust composite scores, the UDS-M+ and UDS3-EF, were computed to represent memory and executive functioning domains. Linear regression models examined independent associations between UDS-M+ and UDS3-EF performance and scam susceptibility. Nested model comparisons evaluated unique contributions of the UDS-M+ and UDS3-EF when included in a joint model. Results: Lower UDS-M+ (b= -0.25, 95% CI [-0.45, -0.04], p= .018) and lower UDS3-EF (b= -0.33, 95% CI [-0.54, -0.12], p= .002) scores were independently associated with greater scam susceptibility after adjusting for age, sex, years of education, and income. However, only UDS3-EF remained significant in a joint model. Post hoc analyses revealed that only memory was associated with scam susceptibility in middle-aged adults whereas only executive functioning was significant in older adults. Conclusions: These findings highlight the importance of monitoring memory and executive functioning across middle to older adulthood when considering susceptibility to scams.

OBJECTIVE: Research on neighborhood context and cognitive health often relies on composite indices that collapse neighborhood socioeconomic status (SES) and aspects of the built environment into a single score. This study examined the extent to which neighborhood SES and built environment were associated with late-life cognitive impairment. METHOD: Participants were 281 predominantly Black older adults who completed the Self-Administered Gerocognitive Exam (SAGE), a brief cognitive screening measure. Participants also provided their home address to obtain four neighborhood metrics: Two composite measures of neighborhood disadvantage, the Environmental Justice Index (EJI) and the EJI Social-Environmental Rank, as well as the EJI Social Vulnerability Rank as a measure of neighborhood SES, and the EJI Environmental Burden Rank to measure exposure to hazardous aspects of the built environment. RESULTS: Lower neighborhood SES was associated with higher odds of cognitive impairment. In contrast, greater environmental burden was associated with lower odds of impairment, with years of education as a moderator; the association was strongest among individuals with high levels of education. The two composite scores were not associated with cognitive impairment. CONCLUSION: Composite measures of neighborhood features may obscure distinct pathways of their effects on cognition.

Site-specific recombinases, such as Cre recombinase (Cre) and FLP recombinase (FLPase), are popular tools that enable precise spatiotemporal control over fluorescent reporter genes. However, studies show that increased Cre expression can lead to cytotoxic phenotypes including DNA damage, cell cycle arrest, cell death, and aneuploidy. In contrast, there is little-to-no known cytotoxicity associated with FLPase. FLPase is considered to be the safer, if less efficient, recombinase. To compensate for decreased efficiency, researchers will often increase expression of the FLPase to ensure a complete gene edit. Despite previous evidence that FLPase is nontoxic at high doses, we report that high expression of FLPase from multi-copy extrachromosomal arrays can disrupt synaptic protein trafficking in C. elegans. We discovered several off-target effects of high FLPase expression including mislocalization of the pre-synaptic marker FLPon::mScarlet::SYD-2 and decreased synaptic abundance, transport, and expression of the ionotropic glutamate receptor subunit GLR-1. Neither overexpression of an inactive FLPase, low activity FLPase, nor mCherry under the same promoter elicited these effects. However, single-copy expression of the FLPase construct reliably tags FLPon::mScarlet::SYD-2 and does not lead to these off-target effects. This work supports growing awareness that tyrosine recombinases can become cytotoxic at high doses.

Chemotaxis assays are widely used to quantify sensory-driven behavioral responses in Caenorhabditis elegans. Sodium azide is commonly used to immobilize animals at assay endpoints, although concerns have been raised that diffusion beyond the endpoint region could affect behavior before a choice is completed. We compared sodium azide-mediated immobilization with post-assay cooling using the repellent 1-octanol and attractant diacetyl. Wild-type animals showed robust avoidance of 30% 1-octanol and attraction to 0.5% diacetyl with either method, across multiple assay durations, and with or without worm food Escherichia coli OP50. These results support post-assay cooling as an alternative endpoint-scoring method.

Objectives Alzheimer's disease (AD) progresses from a cognitively unimpaired stage through mild cognitive impairment (MCI) to dementia. Because language impairment often emerges before dementia, it is a candidate marker of disease stage. Yet the standard batteries of large AD research cohorts rely on a narrow set of tests that mainly evaluate the lexical-semantic domain (i.e., picture naming and verbal fluency), leaving other language domains, such as semantic memory, phonology, morphosyntax, and single-word reading, rarely assessed. We evaluated the diagnostic utility of standard and specialized language tests for distinguishing amyloid-positive MCI and dementia of the Alzheimer's type (DAT) from healthy controls (HC) and from each other. Methods We included 286 participants from the National Alzheimer's Coordinating Center (125 HC, 53 MCI, 108 DAT) assessed with three standard tests from UDSv3 (semantic fluency, letter fluency, and Multilingual Naming Test [MINT]) and nine specialized tests from the FTLD Module (regular and irregular word reading, semantic word-picture matching, semantic associates, Northwestern Anagram Test - Short Form [NAT-S], Northwestern Naming Battery noun and verb naming, sentence repetition, and sentence reading). For each test, the area under the receiver operating characteristic curve (AUC) was computed for DAT vs. HC, MCI vs. HC, and DAT vs. MCI, and AUCs were compared between tests with DeLong's test. Results Eight of 12 measures reached acceptable discrimination (AUC [&ge;] .700) for DAT vs. HC, five for MCI vs. HC, but only semantic fluency and NAT-S for DAT vs. MCI. Semantic fluency showed the highest discrimination in each contrast, though it did not significantly outperform the NAT-S for MCI vs. HC or DAT vs. MCI. MINT, letter fluency, and irregular word reading reached clinically meaningful accuracy in distinguishing MCI and DAT from HC, but not DAT from MCI. The remaining specialized tests reached it only for DAT vs. HC, or not at all. In a post hoc regression, adjusting for cognitive flexibility and working memory attenuated group differences; the DAT difference was no longer significant, whereas the MCI difference remained significant. Discussion Semantic fluency was the strongest single language marker across the AD continuum. Among specialized tests, NAT-S was the most informative, challenging the view that syntax is spared in early AD. Its performance was partly explained by executive function, mainly in DAT, whereas a residual morphosyntactic component remained in MCI, and several specialized tests were limited by ceiling effects. Clinically, the NAT-S may complement semantic fluency for staging, and specialized tests may help characterize heterogeneous language profiles in MCI and DAT.

Sensory abnormalities and sleep disruption frequently co-occur in neurodevelopmental disorders (NDDs), but how sensory input interacts with sleep regulation in NDDs remains poorly understood. Here, we examined vibration-induced sleep (VIS), in which prolonged gentle vibration promotes sleep in Drosophila, in three genetically distinct NDD models: dNf1, dNrx1, and dFmr1. Despite markedly different baseline sleep phenotypes, all three mutants exhibited impaired VIS, identifying disrupted sensory-sleep integration as a shared phenotype across these NDD models. Behavioral responses to vibration, activity-associated CRTC signaling in Nanchung-positive (Nan+) mechanosensory neurons, and thermogenetic activation of Nan+ neurons revealed distinct underlying abnormalities across the three models, indicating that disruption at different points along the sensory-sleep axis can converge on the same behavioral phenotype. The effect of mechanosensory stimulation was also strongly shaped by homeostatic sleep drive: following sleep deprivation, vibration promoted sleep in dNf1 mutants, remained ineffective in dNrx1 mutants, and opposed recovery sleep in dFmr1 mutants. Together, these findings identify impaired sensory regulation of sleep as a point of convergence across genetically distinct NDD models and demonstrate that the expression of this shared phenotype depends on internal state.

Intracellular neurofibrillary tangles formed from hyperphosphorylated tau and extracellular amyloid plaques containing aggregated A{beta}-peptides, specific cleavage products of the Amyloid Precursor Protein (APP), are the primary histopathological hallmarks of Alzheimers Disease (AD), the leading cause of dementia in humans. However, the initiating steps that lead to these pathologies and early neurodegeneration, and the mechanisms by which tau- and A{beta}-induced effects might be linked remain unclear. Using the prostate-like secondary cell (SC) in Drosophila, we recently showed that A{beta} modulates normal APP- and membrane-associated protein aggregation in the dense-core granule (DCG) compartments of the regulated secretory pathway by interfering with subsequent membrane:DCG dissociation. This disrupts endolysosomal trafficking and propagates the resulting endolysosomal defects to other cells that endocytose the secreted abnormal DCG proteins. Here we show that overexpressing human tau also disrupts DCG aggregation and membrane:DCG dissociation inside SC secretory compartments, leading to increased endolysosomal targeting of these compartments. In a genetic screen, we find that knockdown of cofilin, which encodes an actin-severing protein required for dynamic remodelling of microfilaments, generates a similar phenotype. Consistent with this, overexpression of Cofilin, which is known to suppress tau-induced neurodegeneration in flies, reduces tau-induced DCG defects in SCs. Indeed, we find that Cofilin overexpression also suppresses A{beta}-induced degeneration in the fly eye. We conclude that membrane:DCG aggregate dissociation in DCG compartments is disrupted by both tau- and A{beta}-induced genetic changes that are relevant to AD, and this partially involves inhibition of actin cytoskeleton dynamics. Increasing actin remodelling activity can suppress neurodegeneration induced by both tau and A{beta}, suggesting that this process provides an important functional link between them that might be targeted therapeutically.

Introduction Sleep is routinely assessed by psychiatric mental health nurses in acute inpatient wards, where overnight observation forms part of everyday clinical care. These records are repeatedly collected, but observational assessment and activity-based monitoring capture different aspects of sleep and may not be interchangeable. Aim To examine the agreement between actigraphy-based total sleep time and routine nursing sleep assessments in an acute psychiatric inpatient ward. Method This cross-sectional observational study included 94 patients admitted to an acute psychiatric ward. Participants wore wrist actigraphy devices for up to seven consecutive days while sleep duration was concurrently documented by nursing staff as part of routine care. Pearson correlation coefficients assessed linear association, and intraclass correlation coefficients (ICC) assessed agreement. Results Across all participants, nursing-assessed and actigraphy-based total sleep time showed a moderate linear association (Pearson r = 0.629) and good ICC (0.767). Bland-Altman analysis showed a mean bias of 0.20 hours, with 95% limits of agreement from -1.79 to 2.19 hours. Agreement varied across diagnostic groups and was strongest among patients with bipolar mania (r = 0.826; ICC = 0.886). Discussion Routine nursing sleep assessments showed little systematic bias relative to actigraphy at the group level, but wide limits of agreement indicate that the methods are not interchangeable for individual patients. Patient-reported sleep was not measured and should be included in future comparisons.

Sleep disorders are highly prevalent and impose a substantial public health burden, yet the neurobiological mechanisms underlying shared and disorder-specific abnormalities remain incompletely understood. We conducted a pre-registered transdiagnostic study to identify shared and distinct normative macroscale connectivity patterns associated with reported brain abnormalities across insomnia disorder, obstructive sleep apnea, narcolepsy, and rapid eye movement sleep behavior disorder, and to characterize their microscale neurotransmitter and cellular correlates. We obtained peak coordinates from 80 experiments reporting meta-analytic brain abnormalities across these four sleep disorders. Convergent connectivity mapping was then applied to these coordinates using dense connectivity matrices derived from 100 unrelated participants from the Human Connectome Project, with connectivity patterns evaluated relative to a null distribution generated from randomly selected foci. We subsequently examined the spatial correspondence of the identified connectivity maps with 19 neurotransmitter systems using curated positron emission tomography-derived density maps and assessed cellular enrichment across 24 cell-type systems using regional gene-expression profiles from the Allen Human Brain Atlas. Statistical significance was assessed using spin-based permutation testing and false discovery rate correction (pFDR < 0.05). Shared convergent connectivity patterns were identified within the default mode network (zmean = 1.103, pspin,FDR = 0.019), as well as the dorsal attention (zmean = -0.674, pspin,FDR = 0.014) and frontoparietal (zmean = -0.239, pspin,FDR = 0.019) resting-state networks. Disorder-specific analyses revealed broadly overlapping connectivity patterns, with some disorder-related variability. Both transdiagnostic and disorder-specific connectivity patterns showed selective spatial correspondence with multiple neurotransmitter systems, including serotonin, dopamine, norepinephrine, and glutamate, and were enriched for excitatory, inhibitory, and non-neuronal cell types (pFDR < 0.05). These findings indicate that sleep disorders share convergent macroscale connectivity architecture while also exhibiting disorder-specific variations, with the identified network patterns linked to distinct neurotransmitter and cellular profiles. Together, the results provide a normative systems-level framework for understanding shared and distinct neurobiological mechanisms across sleep disorders.

Tardigrades, key ecdysozoan organisms, have poorly characterized daily behavioral rhythms linked to their molting (ecdysial) cycle. We continuously tracked the locomotor activity of the model tardigrade Hypsibius exemplaris using infrared videography and deep learning-based automated tracking under three photic regimes: a light/dark cycle, constant darkness following entrainment, and constant darkness without prior entrainment. We identified a robust endogenous circadian-like rhythm in locomotor activity that persisted in constant darkness, independent of photic input. Although the light/dark cycle enhanced the rhythm amplitude and the overall animal activity, it was not required for rhythmicity. Individual phases varied widely, indicating a lack of population-level synchronization. Furthermore, we developed a behavioral classification system based on activity level, which enables categorizing distinct behaviors. Behavioral patterns were modulated by distinct ecdysial stages, with quiescence gating premolt and time-of-day dependent patterns in feeding and wandering. These findings provide evidence consistent with an endogenous, circadian-like timing system in tardigrades that integrates daily activity with molting cycles and establish H. exemplaris as a promising model for studying ecdysozoan chronobiology.

Metabolic alterations commonly accompany neurodevelopmental disorders and may contribute to their pathophysiology. Neurofibromatosis type 1 (OMIM 162200) is a genetic disorder that results from mutations in the NF1 gene and its encoded neurofibromin protein (Nf1). The disorder is multisystemic, affecting multiple aspects of development, physiology, and brain function. In addition, recent evidence suggests that Nf1 deficiency alters metabolic function in both humans and animal models. Whether the metabolic alterations result from changes in neurodevelopment is not known. Here we approach this question in Drosophila melanogaster, which expresses a conserved NF1 gene, exhibits phenotypes reminiscent of the human disease, and shares key developmental mechanisms with humans. Flies with nf1 mutations or RNAi-mediated knockdown exhibit altered metabolism in adulthood. Conditional Nf1 inactivation revealed that the adult metabolic phenotype resulted from loss of Nf1 in neurons during a developmental critical period (third instar larva/pupa), which corresponded to the period of nervous system maturation. Prior to the developmental critical period, nf1 mutants did not exhibit metabolic difference - rather, the metabolic alterations appeared only after the critical period. This suggests that the adult phenotype results from the onset of the developmental alteration during the critical period. High-resolution respirometry on adult mitochondria revealed no differences in complex I/II function or fatty acid oxidation between nf1 mutants and controls, suggesting that the metabolic alterations localize upstream of the electron transport chain at the cellular level. Overall, these data suggest that loss of Nf1 alters adult metabolism via effects during a critical period of nervous system development.