Journal of Neurogenetics

Animals balance staying in a favorable environment with exploring new ones. In C. elegans chemotaxis, the process by which worms migrate toward an attractant has been extensively studied. However, what happens after they reach it remains largely unexplored, partly because conventional assays immobilize worms at the point of arrival. Here, we quantitatively analyzed chemotactic behavior upon reaching an attractive odor source using an immobilization-free chemotaxis assay. We observed that 62% animals left the isoamyl alcohol region after initially approaching it, a behavior we termed "leaving behavior." Quantitative analysis revealed that leaving behavior represents a distinct locomotor state compared with free-moving, high-concentration odor avoidance, and approach behavior. To test whether leaving behavior is related to olfactory adaptation, we analyzed mutants in adaptation-related genes. The proportion of leaving behavior was significantly increased in egl-4 loss-of-function mutants compared with wild-type animals, whereas arr-1 mutants showed no significant difference. These results suggest that egl-4 negatively regulates leaving behavior, suggesting a role for this kinase in stabilizing post-arrival behavioral states beyond its known function in olfactory adaptation. Our findings indicate that chemotaxis involves dynamic behavioral transitions even after reaching an attractant, consistent with an exploration-exploitation trade-off framework.

Epilepsy affects approximately 30% of individuals with autism spectrum disorder (ASD). Consistent with these observations, while PRICKLE mutations are primarily linked with epilepsy, there is an enrichment of pathogenic DNA sequence variants in PRICKLE genes carried by individuals with ASD. Nonetheless, a connection between PRICKLE function and ASD warrants further investigation. Here, we show that a seizure-prone Drosophila prickle mutant (prickle-spiny-legs, or pksple) exhibits learning and memory deficits, increased pain sensitivity, both communication and social interaction difficulties, and restrictive repetitive grooming behaviors, all of which are strongly correlated with ASD, while a non-seizure prone prickle mutant (prickle-prickle, or pkpk) does not, thereby providing a direct genetic connection between epilepsy and ASD through prickle. Comparing headed versus headless pksple mutants, we also show that the excessive grooming requires higher level cognitive processing from the brain. Finally, both pksple and pkpk mutants exhibit circadian rhythm defects, another feature correlated with ASD, as well as distinct yet overlapping neurological anomalies in processes that include innate immune response, oxidative stress response, neuronal cell death, neurodegeneration, motor dysfunction and reduced lifespan, likely reflecting the unique isoform expression patterns observed in the developing CNS. Collectively, this study highlights the broadscale effects of PRICKLE mutations that extend beyond the primary clinical features of epilepsy to include several of the core features of ASD.

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.

Parkinsons disease is predominantly characterized by dopaminergic neurodegeneration linked to toxic aggregation of -synuclein. Genipin, a bioactive iridoid, was previously shown to improve the motility and survival deficits caused by pan-neuronal expression of native -synuclein in a transgenic Drosophila melanogaster model system. We show that expression of -synuclein causes sleep deficits and that genipin treatment rescued these sleep deficits, increasing total sleep and consolidating nighttime sleep relative to untreated -synuclein-expressing fruit flies. Our findings extend genipins protective profile in Drosophila melanogaster and highlight sleep regulation as an additional phenotype responsive to -synuclein-targeted interventions.

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.

Introduction: Bipolar disorder (BD) has been associated with increased medical burden and accelerated biological aging. Long non-coding RNAs (lncRNAs) regulate molecular pathways related to cellular senescence, inflammation, and telomere maintenance, which are implicated in both BD and aging. This study examined whether aging-related lncRNA expression reflects familial vulnerability or illness-specific effects, and whether childhood trauma and lifestyle factors modulate these signatures within a gene-environment framework. Methods: In this cross-sectional study, expression levels of aging-related lncRNAs, including Antisense Non-coding RNA in the INK4 Locus (ANRIL), HOX Transcript Antisense Intergenic RNA (HOTAIR), Nuclear Enriched Abundant Transcript 1 (NEAT1), Taurine Upregulated Gene 1 (TUG1), Metastasis-Associated Lung Adenocarcinoma Transcript 1 (MALAT1), Growth Arrest-Specific 5 (GAS5), and Telomerase RNA Component (TERC), were measured in peripheral blood mononuclear cells (PBMCs) from individuals with bipolar disorder (BD) (n=68), siblings without BD diagnosis (SIB) (n=54), and healthy controls (HC) (n=70) using quantitative reverse transcription polymerase chain reaction (RT-qPCR). Childhood trauma and lifestyle were assessed using the Childhood Trauma Questionnaire (CTQ) and the Healthy Lifestyle Profile II (HPLP-II). Principal component analysis generated a composite aging-related lncRNA factor. Results: At the individual transcript level, NEAT1 and TERC were elevated, whereas GAS5 was reduced, in both BD and SIB relative to HC. The aging-related lncRNA composite score was higher in BD and SIB than in HC (F = 7.315, p = 0.001). Familial liability to BD (presence vs. absence of familial liability) showed a significant main effect on the composite score (F(1,182)=8.18, p=0.005) and interacted with childhood trauma (F(1,182)=10.14, p=0.002). In multivariable models, total CTQ and physical neglect were independently associated with lower composite scores, while familial liability remained a positive predictor (all p<0.001). Conclusions: Aging-related lncRNA alterations mark familial vulnerability to BD and are shaped by childhood trauma within a gene-environment interaction framework.

Defects in Drosophila Cu2+/Zn2+ superoxide dismutase (encoded by the gene Sod1) lead to elevated oxidative stress and a drastically shortened lifespan. To contrast the effects of aging and oxidative stress on nerve conduction, synaptic transmission, and muscle excitability, we developed an easily accessible adult abdominal neuromuscular preparation, utilizing the male-specific Muscle of Lawrence (MOL) in Drosophila. The large size of MOL facilitated analyses of presynaptic nerve signals and postsynaptic responses that could result in sizable excitatory junctional potentials (EJPs) evoking full-blown muscle action potentials (APs) which were terminated rapidly by a characteristic afterhyperpolarization (AHP). Aged wild-type (WT) individuals (80 days or older) exhibited diminished neuromuscular transmission, mainly reflecting declines in motor axon conduction, with synaptic transmission remaining largely intact (since robust EJPs could still be evoked when nerve terminals were directly stimulated electrotonically). Additionally, muscle APs showed enhanced depolarizing peaks and weakened AHPs during current injection, suggesting weakening in repolarizing K+ currents. Chronologically younger Sod1 mutants (up to 30 days) displayed similar trends of neuromuscular changes, confirming a major role of oxidative stress in aging. However, certain distinctions exist in muscle membrane properties and transmitter release machinery. A clear increase in muscle membrane resistance was seen in Sod1 but not in aged WT. Additionally, unlike normal spontaneous release of synaptic vesicles leading to miniature EJPs (mEJPs), extremely enlarged spontaneous transmitter discharges occurred in aged WT but was never seen in Sod1, indicating a distinct, aging-specific alteration in transmitter release regulation. Notably, our work revealed considerable variation among individuals, ranging from transmission failure to largely intact neuromuscular functions, demonstrating the stochastic nature of functional declines due to aging and oxidative stress. Moreover, this study uncovered a well-defined common vulnerability, i.e. weakening of the Ca2+-activated BK current that caused drastic reduction in AHP in both aged WT and Sod1 mutants, as confirmed by their diminishing sensitivity to the BK channel blocker paxilline, which caused striking alterations in the AHP in WT control.

The neuropathology of Parkinson's disease is characterized by -synuclein (-syn) aggregation and dopaminergic (DAergic) neurodegeneration. While neuronal loss in C. elegans -syn-induced neurodegeneration models is temporally age-dependent, prior research indicates it is uncoupled from the organismal aging process. Here we examined transgenic C. elegans expressing human A53T -syn in DAergic neurons to determine the impact of localized DA metabolism on both neurodegeneration and organismal lifespan. Increasing endogenous DA levels through overexpression of tyrosine hydroxylase (CAT-2) exacerbated A53T-induced DAergic degeneration, whereas DA depletion via{Delta} cat-2 mutation rescued neuronal survival. By mutating a DA interaction motif within -syn, neurodegeneration was rendered insensitive to DA manipulation, thus confirming a structural basis for in vivo toxicity. We identified a DA--syn interaction that acts as a common upstream bridge whereby localized stress induces physiological responses in C. elegans. Genetically, this biochemical interaction acts as a pleiotropic trigger driving two compartmentalized responses: localized DAergic neurodegeneration via oxidative stress, and organism-wide, TFEB/hlh-30-dependent proteostatic remodeling that extends lifespan. Modulating autophagy, without exacerbating DA-mediated oxidative stress, represents a promising strategy to preserve adaptive systemic remodeling while limiting targeted neuronal damage.

Sleep gets worse with age and is correlated with risk for disease and mortality. The possibility that poor sleep causes aging to accelerate has prompted interest in improving sleep to slow aging and prevent disease. However, the existing evidence on the link between poor sleep and accelerated aging is unclear. Here, we tested for correlation and causation between poor sleep and accelerated aging using five independent datasets of adults (total N > 64,000). We found strong evidence for a correlation between poor sleep and fast aging that is consistent across young, middle, and late adulthood and across aging biomarkers derived from different tissues and modalities. We found that this correlation is robust to the influence of chronic disease burden, but not to the influence of shared genetic and early environmental factors among twins. Finally, we found mixed evidence for a causal influence of poor sleep on accelerated aging using Mendelian randomization. Our findings indicate that the correlation between poor sleep and accelerated aging is highly robust; however, the claim that poor sleep causes aging to accelerate is not consistently supported.

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.

Genetic-background studies require defined perturbations that can be crossed reproducibly into many recipient backgrounds. We generated a Drosophila dilp2GS-rpr donor line for adult-inducible ablation of insulin-producing cells (IPCs), which secrete insulin-like peptides and provide a tractable model of insulin-deficient metabolic physiology. This line carries dilp2-GeneSwitch-GAL4 and UAS-reaper in cis on the same second chromosome homolog over a balancer. PCR genotyping and sequencing confirmed both transgenic elements in the candidate recombinant line. RU486 induction reduced dilp2 mRNA expression, supporting partial IPC ablation. Treatment-duration testing identified 8 days of RU486 as sufficient to increase whole-body glucose in the dilp2GS-rpr line but not in the background-matched control; food intake did not differ between RU486- and vehicle-treated flies. Across metabolic assays, whole-body glucose showed the clearest RU486- and line-dependent phenotype. This validated dilp2GS-rpr line enables testing how recipient genetic backgrounds modify inducible IPC/DILP metabolic phenotypes and provides a framework for similar linked donor-line resources.

Overexpression of -synuclein (-syn), an inherently disordered protein, triggers chronic activation of the mitochondrial unfolded protein response (UPRmt) pathway in Caenorhabditis elegans with enhanced dopaminergic (DAergic) neurodegeneration. Introduction of a loss-of-function(lf) mutation in atfs-1, the main transcriptional regulator of the UPRmt, into -syn nematodes results in significant neuroprotection from -syn-induced DA neuron loss, indicating that compensatory mechanisms provide neuroprotection. We performed a F3 forward genetic screen in C. elegans atfs-1(lf) mutants to identify molecular components associated with the modulation of neurodegeneration via UPRmt signaling in -syn-expressing DA neurons. Homozygous mutant animals were examined for enhanced neurodegeneration; multiple independent alleles were uncovered. Among these, we identified new nonsense alleles encoding the histone lysine demethylases (H3K27me3), jmjd-1.2 and jmjd-3.1. Another line carried a nonsense allele of twk-14. This gene encodes a conserved protein termed KCNK12 in mammals that facilitates passive background K+ leak currents to set and stabilize resting membrane potential. To further examine the association of these gene products in DA neurodegeneration, mutants and/or RNA interference were employed. DA neurodegeneration was observed in the -syn + atfs-1(lf) background when jmjd-1.2, jmjd-3.1, or twk-14 were individually depleted. These results provide evidence that jmjd-1.2 and jmjd-3.1, which encode previously characterized H3K27me3 demethylases, and the uncharacterized twk-14 gene product, orthologous to human KCNK12, naturally confer protection from -syn neurotoxicity.

Dauer formation and L1 arrest are stress-responsive developmental strategies that enable Caenorhabditis elegans to survive unfavorable conditions. These responses are regulated by environmental cues, including food availability and pheromone signals that communicate population density. However, how dauer entry, L1 arrest, and density-dependent signaling collectively influence long-term population dynamics remains poorly understood. In this study, populations of daf-22 and daf-16 mutants with impaired dauer formation, starvation arrest, and pheromone signaling were compared under control and starvation stress. Measurements of developmental stages were used to evaluate how genotype influenced population growth, developmental stage composition, starvation response, and recovery over time. This population-level approach links individual developmental decisions and inter-organismal communication to broader patterns of persistence and population change. The results show that daf-16 and daf-22 mutant populations differed from wild type in their recovery ability following nutrient deprivation as well as in the stage distributions within the population. These findings suggest that dauer signaling contributes broadly to population persistence by coordinating developmental arrest, reproduction, survival, and recovery. Overall, this work supports the interpretation of dauer formation as a larger population level survival program rather than a single isolated developmental outcome.

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.

Background: Shiftwork disrupts natural sleep-wake cycles, alters light exposure patterns, and contributes to circadian misalignment. Detrimental health consequences associated with shift work include elevated risk for metabolic disorders, cardiovascular disease, cancer and all-cause mortality. Healthcare workers have one of the highest rates of shift work exposure, yet there are relatively few non-pharmacological interventions (with good evidence) developed to improve sleep outcomes in this population. Objective: A pre-post pilot interventional study assessed the acceptability and perceived effectiveness of commercial noise-masking earbuds on improving subjective sleep characteristics among National Health Service (NHS) healthcare staff working fast rotating shifts. Methods: Noise-masking sleep earbuds (Kokoon NightBuds) were worn for a pilot six-week intervention by twenty-seven NHS nurses (aged 26-43 years, 88.9% female) working fast rotating shifts from the EClocker Study. Sensors inside the earbuds were paired with a smartphone app to monitor sleep. An audio library in the smartphone app delivered personalised relaxation exercises and sleep techniques drawn from cognitive behavioural therapy for insomnia (CBT-I). A pre-post two-week monitoring period with daily smartphone-based Experience Sampling Methods (ESM) captured perceived daily sleep patterns. Acceptability and perceived effectiveness of the earbuds in promoting better sleep outcomes was assessed. Results: Use of the noise-masking sleep earbuds over a six-week period was associated with positive sleep improvement trends and elicited promising acceptability. Almost two thirds of NHS fast rotating shift nurses (63%) subjectively reported reductions in general sleep disturbance symptoms (PSQI Global), one in four experienced perceived sleep quality improvements (SQ; 25.9%), one in five reported sleeping longer (TST; 22.2%), and a third perceived falling asleep faster (SOL; 33.3%), had better sleep efficiency (SE; 33.3%) and improved daytime dysfunction (33.3%) (PSQI subcomponent scores). Sleep diaries (CSD) collected daily using smartphone-based ESM also demonstrated small improvements post-sleep earbud use; nurses reported sleeping an average 18 minutes longer (TST) and fell asleep more easily, on average 11 minutes faster (SOL). Sleep earbuds were generally well tolerated; 56% of nurses reported the earbuds as (somewhat to very) helpful, 52% reported (somewhat to strongly) falling asleep more easily (SOL), 44% felt (somewhat to strongly) their sleep quality was improved (SQ) and 30% agreed (somewhat to strongly) they slept longer (TST) and had less disturbed sleep. Conclusions: To our knowledge, this is the first study in Europe to pilot noise-masking earbuds as a potential non-pharmacological aid to improve sleep-wake behaviours or mitigate fatigue for healthcare staff. Preliminary results showed promising acceptability and (small) perceived sleep improvement trends following a targeted six-week earbud intervention in NHS fast rotating shift nurses.

Objective: Regression-based normative approaches are widely used in neuropsychology but often rely on score transformations to satisfy model assumptions. We compared previously published linear regression (LR)-based norms with norms derived using Generalized Additive Models for Location, Scale and Shape (GAMLSS) for the brief cognitive battery used in the Norwegian Dementia Disease Initiation (DDI) cohort. Method: GAMLSS norms were developed using the same normative samples as the original LR norms for the Consortium to Establish a Registry for Alzheimers Disease (CERAD) word list test, Trail Making Test (TMT) A and B, FAS phonemic fluency, and Visual Object and Space Perception Battery (VOSP) Silhouettes. Expected low-score frequencies and empirical base rates were assessed in a normative subsample (n = 131). Clinical implications were evaluated in the DDI clinical cohort (n = 643) using Mild Cognitive Impairment (MCI) classification, two-year diagnostic stability and change, and cerebrospinal fluid (CSF) biomarkers. Results: Compared with LR norms, GAMLSS yielded lower frequencies of low scores, primarily driven by CERAD delayed recall. Nevertheless, concordance between approaches was high (kappa = 0.91), with only 4.2% discordant classifications. Two-year diagnostic stability and change were broadly similar across approaches, and CSF biomarker profiles did not clearly favor either normative method. Conclusions: GAMLSS provided a more faithful representation of neuropsychological score distributions, particularly for bounded and non-normal outcomes. However, downstream clinical differences were modest in this setting, suggesting that well-calibrated LR norms may remain robust for clinical classification.

Friedreich ataxia (FRDA) is a neurodegenerative and cardiac disease caused by GAA repeat expansions within the first intron of the FXN gene, leading to reduced frataxin expression. Frataxin is required for iron sulfur cluster (ISC) biosynthesis, and its deficiency results in multiple cellular dysfunctions, including mitochondrial iron overload. Although altered iron homeostasis has been reported in several frataxin-deficient models and in FRDA patients, its contribution to disease progression remains debated. Here, we used a GAA expansion-based Drosophila model of FRDA, termed fh-GAAs, to investigate the impact of reducing intestinal iron absorption on disease progression. We first found that iron accumulation was tissue-specific and predominantly affected the central nervous system. Furthermore, glial cells were affected more severely than neurons, suggesting an increased vulnerability of glia to frataxin deficiency. Reducing intestinal iron uptake, either through treatment with bathophenanthroline disulfonic acid (BPS), an extracellular iron chelator, or by gut-specific silencing of the iron transporter Malvolio, nearly doubled fly survival. BPS treatment also improved sensitivity to dietary iron, enhanced locomotor performance, fully restored normal brain size, and prevented glial alterations. Altogether, our findings identify glial cells as early and preferential targets of frataxin deficiency in an iron-dependent manner and support the in vivo relevance of intestinal iron uptake as a potential modulator of disease severity in FRDA.

Objectives: The 10-item Centre for Epidemiological Studies Depression Scale (CES-D-10) has been used in cohort studies with scores of >= 8 and >= 10 used to indicate clinically significant symptoms or probable depression. We examined whether observations crossing these thresholds displayed core affective features expected in individuals who might be suffering with a clinically significant major depressive episode. Methods: This was a descriptive analysis of repeated CES-D-10 assessments in the ASPirin in Reducing Events in the Elderly eXTension (ASPREE-XT) longitudinal cohort study of 19,114 participants. We identified observations of 'probable depression', defined as a CES-D-10 score >= 8 and then examined scores on item 3 ("I felt depressed") and item 8 ("I was happy"). The primary outcome was the proportion of threshold-positive CES-D-10 observations with minimally depressed mood and preserved happiness. Results: Over 13 years, 27,417 observations met the threshold of CES-D-10 >= 8. Of these, 13,356 observations (48.7%) had minimally depressed mood and preserved happiness. Conclusion: A substantial proportion of observations considered 'probable depression' had little or no depressed mood, together with preserved happiness. CES-D-10 sum scores should be used with caution as a proxy for major depressive disorder in older adults.

Severe worry is a transdiagnostic syndrome associated with significant morbidity in older adults. In this study, we aim to infer worry-related mental states though brain activity timeseries. We acquired fMRI on two cohorts (N=116 and N=88), using an in-scanner worry induction and reappraisal task. We trained a recurrent long short-term memory (LSTM) neural network, using the first cohort as the train/validation and the second cohort as an independent test set. We predicted worry induction, reappraisal, and neutral states (area under the curve 0.89, 0.77, 0.91 for the test set and 0.78, 0.63, 0.81 for the independent set). The model was most accurate when participants reported high worry during the induction state. Dorsal attention network, and networks seeded on the anterior hippocampus, and supplementary motor area were most important for predicting worry states. The LSTM approach may have critical translational implications for identifying and treating severe worry in older adults.

The increasing deployment of artificial intelligence (AI) assistive systems across healthcare, education, and organisational domains necessitates a deeper understanding of dispositional factors shaping trust and acceptance. This study investigated the Big Five personality traits as predictors of trust in and acceptance of AI assistive systems among a large adult sample (N = 380) in Makurdi Benue State. Anchored in the Technology Acceptance Model (TAM) developed by Davis (1989), the study examined both direct and indirect pathways linking personality traits to AI acceptance through trust. Participants completed standardised measures of the Big Five Inventory, Trust in AI Scale, and AI Acceptance Scale. Data were analysed using structural equation modelling (SEM) with maximum likelihood estimation. The hypothesised model demonstrated good fit indices (CFI = .84, TLI = .82, RMSEA = .05). Openness to experience ({beta} = .34, p < .001) and agreeableness ({beta} = .27, p < .01) significantly predicted trust in AI systems, which in turn strongly predicted AI acceptance ({beta} = .62, p < .001). Neuroticism negatively predicted trust ({beta} = -.29, p < .001), while conscientiousness showed a modest positive direct effect on acceptance ({beta} = .18, p < .05). Extraversion was not a significant direct predictor but exerted an indirect effect through trust. Mediation analysis confirmed that trust significantly mediated the relationship between personality traits and AI acceptance. The findings underscore the centrality of dispositional traits in shaping technological trust formation and highlight the psychological architecture underlying human AI interaction. These results contribute to social psychological theory and provide empirical guidance for designing personality sensitive AI systems to enhance user adoption and sustained engagement.