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Anxiety disorders are highly prevalent yet lack objective biomarkers. Whereas threat-related attentional biases are well documented, less is known about broader eye movement alterations that may characterise anxiety.
Aims
To characterise multi-paradigm eye movement profiles in anxiety disorders and evaluate their potential as behavioural markers for disorder differentiation.
Method
Eye movements were recorded in 91 patients with anxiety disorders, 118 with depressive disorders and 98 healthy controls during free viewing of neutral-stimuli, smooth-pursuit and fixation-stability tasks. Principal component analysis was applied to derive latent eye movement dimensions, which were then tested for group differences, associations with symptom severity and classification performance.
Results
Compared with both patients with depression and healthy controls, patients with anxiety disorders exhibited hyper-scanning during free viewing, characterised by increased saccade frequency and path length, and hyper-pursuit during smooth pursuit, reflected in increased velocity gain, fewer intrusive saccades and more catch-up saccades. Principal component analysis identified six latent components, among which active visual exploration, pupillary arousal and smooth-pursuit control demonstrated robust group differences. Machine learning models trained on 6 components yielded areas under the receiver operating characteristic curve of 0.82 for anxiety versus healthy controls, 0.83 for depression versus healthy controls and 0.61 for anxiety versus depression.
Conclusions
Hyper-scanning and hyper-pursuit emerge as defining eye movement signatures of anxiety, linking core mechanisms of vigilance and prediction with measurable behavioural markers. These insights position eye-tracking as a promising behavioural modality for mechanism-informed differentiation across affective disorders.
Perinatal depression and anxiety are major contributors to maternal morbidity, with a disproportionate burden in low- and middle-income countries. In Pakistan, common and modifiable biological risks, including anemia and vitamin D deficiency, may interact with psychosocial factors to influence perinatal mental health. This cohort study enrolled 152 pregnant women from a public hospital in Islamabad; 147 completed baseline assessments (12–32 weeks gestation) and 100 were followed at 6–8 weeks postpartum. Validated Urdu versions of the EPDS, GAD-7, and MSPSS were used alongside hemoglobin and vitamin D assessments at both time points. Longitudinal analyses were conducted using generalized linear mixed models, supplemented by cross-sectional and mediation analyses.Depression was prevalent antenatally (41.5%) and increased postpartum (57.0%), while anxiety declined from 25.2% to 12.0%. Higher hemoglobin was protective against antenatal depression (OR = 0.66) and anxiety (OR = 0.65), but not in longitudinal models. Vitamin D deficiency predicted postnatal depression (OR = 3.15), while sufficiency was associated with remission. Social support showed a strong protective effect (OR = 0.24) and mediated 40% of the hemoglobin–depression association. Baseline symptom severity was the strongest predictor of postpartum outcomes. These findings highlight a substantial burden and point to modifiable nutritional and psychosocial targets for intervention.
Associations of cerebrospinal fluid biomarkers with sleep, functionality and the MDS-UPDRS in dementia with Lewy bodies (DLB) and late-onset Alzheimer’s disease (AD) help elucidate their pathophysiological underpinnings.
Methods:
Consecutive outpatients with DLB and AD were matched by sex, cognitive scores and dementia stage, along with cognitively healthy controls matched by age and sex to investigate associations of cerebrospinal fluid amyloid-β (Aβ42,Aβ40,Aβ38), tau, phospho-tauThr181, ubiquitin, α-synuclein and neurofilament light (NfL) with sleep duration, Schwab & England scale and MDS-UPDRS, adjusted for sex, age and APOE-ϵ4 alleles.
Results:
Patients with DLB (APOE-ϵ4+:n=11, 76.64±9.0years; APOE-ϵ4-:n=16, 79.75±9.0years) were paired with patients with AD (APOE-ϵ4+:n=12, 80.17±5.7years; APOE-ϵ4-:n=15, 81.67±5.9years) and controls (APOE-ϵ4+:n=4, 82.00±6.4years; APOE-ϵ4-:n=23, 77.87±9.0years); two-thirds were women. APOE-ϵ4 carriers with dementia had more amyloidosis, higher phospho-tauThr181/Aβ42 and α-synuclein/Aβ42. In DLB, APOE-ϵ4 non-carriers had lower Schwab & England scores and higher MDS-UPDRS-I&II scores, lower tau/phospho-tauThr181 and higher ubiquitin and NfL than APOE-ϵ4 carriers. In controls, APOE-ϵ4 non-carriers had lower Aβ42 and Aβ42/Aβ38, higher phospho-tauThr181/Aβ42 and α-synuclein/Aβ42 than APOE-ϵ4 carriers. In DLB, sleep duration was associated with Aβ38 and α-synuclein and inversely associated with tau/phospho-tauThr181 and tau/ubiquitin; Schwab & England scores were associated with tau/ubiquitin and inversely associated with tau/phospho-tauThr181; MDS-UPDRS-I&II was associated with Aβ42/Aβ38; MDS-UPDRS-III was associated with tau/phospho-tauThr181; MDS-UPDRS-V ON was associated with Aβ42 and Aβ42/Aβ40, and MDS-UPDRS-V OFF was associated with Aβ42, Aβ42/Aβ40 and Aβ42/Aβ38. In AD, MDS-UPDRS-III was associated with ubiquitin.
Conclusion:
Biomarker ratios were superior to isolated biomarkers in associations with motor and non-motor experiences in DLB, though not so prominently in AD due to less motor impairment.
Chapter 14 allows us a look at the trajectories in brain imaging technology and research while acknowledging the field’s unpredictable evolution. It examines how existing tools are being refined, with functional MRI achieving submillimeter resolution and EEG sampling rates reaching 100,000 Hz, while highlighting the growing influence of private industry through initiatives like Neuralink, Facebook’s Building 8, and Google Brain. The chapter analyzes the scientific value of multimodal imaging approaches that combine complementary techniques such as EEG-fMRI to leverage both high temporal and spatial resolution. It discusses how large-scale collaborative efforts including the Human Connectome Project and Brain Initiative are reshaping our understanding of neural connectivity despite the challenges of modeling the brain’s extraordinary complexity. The emergence of biomarkers receives particular attention, emphasizing how machine learning algorithms are enhancing our ability to detect neurological and psychiatric conditions through brain imaging data. Recent technological innovations are surveyed, including miniaturized MRI scanners, real-time imaging analysis, optically pumped magnetometry, and functional ultrasound imaging, all pointing toward more accessible and sophisticated brain measurement capabilities. The chapter concludes with practical guidance for newcomers to the field and consideration of ethical dimensions, emphasizing that brain imaging technologies should advance human wellbeing rather than enable control or manipulation. Throughout, the chapter maintains that while specific trajectories remain uncertain, the overall direction is toward increasingly precise, accessible, and clinically valuable brain imaging technologies.
Pregnancy of unknown location (PUL) is a non-diagnostic classification term that arises when a patient has a positive urinary pregnancy test, but a pregnancy cannot be visualised on a transvaginal ultrasound scan. The management of patients classified with a PUL is often variable. It should however be dictated by triaging women into either at low-risk or high-risk of complications. Various management protocols exist to triage PUL including: 1. a single hCG and progesterone level, 2. hCG ratio (hCG at 48 hours / hCG at 0 hours) and 3. risk prediction models utilising hCG and progesterone levels.
Circulating tumour cells (CTCs) are unique cells that originate from the main tumor site. They circulate in the bloodstream, and are implicated in metastasis, immune evasion and recurrence in various cancers. Associated biomarkers of importance for CTC detection include epithelial cell adhesion molecule (EpCAM), human epidermal growth factor receptor 2 (HER2), programmed death ligand-1 (PD-L1), cluster of differentiation 45 (CD45) and other cancer-specific biomolecules. Their roles as standalone biomarkers, have been thoroughly examined in CTC detection, isolation and targeting.
Methods
This review collates key findings on CTC characteristics and biomarker identification. The most recent CTC isolation and detection technologies are discussed, along with individual approaches based on inclusion and exclusion of cell-specific biomarkers. Emerging treatments integrating CTCs, including nanocarrier-mediated drug delivery, have been analyzed. We have discussed both the physical and research barriers in the current landscape.
Results
Recent advances have determined that such biomarkers are more reliable when associated with secondary biomarkers, due to concerns regarding immune evasion and low sensitivity. The identification of these molecules has fast-tracked the development of several groundbreaking technologies.
Conclusion
The prognostic and predictive role of CTCs in various cancers revealed promising results. The development of integrative therapeutics can enhance patient survival and quality of life. These advancements depend on addressing key issues, such as molecular characterization and low abundance of CTCs.
Early detection of respiratory decline is crucial in amyotrophic lateral sclerosis (ALS). We tested if nocturnal polysomnography (PSG) predicts dyspnea onset in mild ALS patients with preserved daytime function.
Methods:
In this study, 41 mild ALS patients (ALS Functional Rating Scale-Revised [ALSFRS-R] ≥ 37, sitting forced vital capacity [FVC] ≥80% predicted, no dyspnea) and 41 matched controls underwent baseline assessment, including ALSFRS-R scoring, pulmonary function tests, and overnight PSG. ALS patients were followed for 12 months. Baseline apnea–hypopnea index (AHI) and oxygen saturation (mean SpO2, minimum SpO2) were analyzed as continuous predictors and using exploratory thresholds (AHI ≥ 5 events/h, min SpO2 ≤ 88%, mean SpO2 ≤ 95%) for dyspnea onset (Dyspnea-ALS-15 [DALS-15] > 0).
Results:
Compared to controls, ALS patients had significantly higher AHI (p = 0.004) and lower minimum SpO2 (p = 0.018). The ALSFRS-R orthopnea subscore showed a significant positive correlation with mean and minimum SpO2 (P < 0.05). Cox regression identified baseline AHI (HR 1.08 per event/h; 95% CI 1.01–1.15, p = 0.028) and minimum SpO2 (HR 0.94 per %; 95% CI 0.88–0.99, p = 0.033) as independent predictors of dyspnea onset within 12 months. Thresholds AHI ≥ 5 (HR 2.28, p = 0.031) and min SpO2 ≤ 88% (HR 2.42, p = 0.027) also predicted increased risk. Patients meeting ≥1 threshold (n = 25/37) showed trends toward greater FVC and ALSFRS-R decline.
Conclusions:
In patients with mild ALS and normal daytime function, specific nocturnal PSG parameters (AHI, minimum SpO2) predicted the risk of dyspnea within 12 months. This longitudinal study provides novel evidence that PSG could identify early respiratory vulnerability in the incipient stage, earlier than conventional FVC-based monitoring, supporting its potential utility in refining early intervention strategies. Validation in larger cohorts is warranted.
Collar monitoring devices are used in animals for the minimally invasive collection of physiological data, using software and algorithms to provide general health trends. There is potential to utilise the raw data collected from these devices to improve animal monitoring strategies and intervention points in animal disease studies. We aimed to develop an algorithm for the early detection of highly pathogenic African swine fever disease in research pigs (Sus scrofa), using data collected via modified PetPaceTM health monitoring collars. Pigs from two other studies (n = 6 per study, total n = 12) were opportunistically available and fitted with collar monitors for the daily collection of pulse rate, respiratory rate and heart rate variability, prior to and after experimental challenge with highly pathogenic African swine fever virus. Collar monitors detected a decreased mean, and increased variability, of pulse rate and heart rate variability in pigs post-challenge, which was not detected by single daily point-in-time measurements. The incidence of abnormal pulse rate, respiratory rate and heart rate variability readings increased in pigs after infection with highly pathogenic African swine fever, with increasing abnormal readings occurring both prior to the onset of, and during, clinical disease. A preliminary non-AI algorithm utilising these data detected disease in 100%, and predicted disease onset in 67%, of infected pigs. This paper describes how health-monitoring collars can be used to improve the early detection of African swine fever disease in pigs. Additionally, it provides a potential framework for developing and using non-AI algorithms in other disease models, to enhance animal monitoring and welfare outcomes in research animals.
The intensification of pig (Sus scrofa domesticus) production systems raises concerns regarding animal welfare, particularly during pre-slaughter conditions, a phase associated with significant stress. Saliva is increasingly recognised as a non-invasive matrix for detecting stress-related biomarkers in pigs. This preliminary study aimed to explore salivary protein changes in pigs subjected to two distinct pre-slaughter conditions at the slaughterhouse, improved (Group A) and stressful (Group B), by tandem mass tag (TMT)-based proteomics. Proteomic analysis of saliva from three pigs per group revealed 13 proteins with a statistically significant difference in relative abundance between the groups. Group B showed elevated levels of proteins linked to metabolic stress, inflammation, and coagulation, such as cystatin-C and fibrinogen chains, while proteins like vimentin and follistatin-related protein were decreased. Cystatin-C and vimentin were further validated by immunoassays in 12 additional pigs per group, confirming their differential abundance. These findings suggest that salivary cystatin-C and vimentin, along with the other 11 proteins that showed changes at proteomics, may serve as candidate biomarkers of acute stress at slaughter. While further validation is required, our results support the potential of salivary proteomics for welfare monitoring in livestock.
Young-onset dementia (YOD), defined by symptom onset before age 65, encompasses diverse aetiologies and presents with prominent neuropsychiatric symptoms (NPS) that often accompany or exacerbate cognitive decline. However, the pathological mechanisms linking NPS, cognition, and biomarkers remain unclear. It was hypothesised that relationships between NPS and cognition would be mediated or moderated by cerebrospinal fluid (CSF) biomarker levels in individuals with YOD.
Methods:
This retrospective, cross-sectional study included 46 participants with YOD (24 with Alzheimer’s disease [AD], 22 with non-AD dementias) diagnosed at the Neuropsychiatry Centre, Royal Melbourne Hospital. NPS were measured using the Depression Anxiety and Stress Scale and Cambridge Behavioural Inventory-Revised. Cognition was assessed using standardised neuropsychological assessments. CSF amyloid-β (Aβ42), phosphorylated tau 181 (P-tau181), total tau (T-tau), and neurofilament light chain protein (NfL) were analysed. General linear models (GLMs) examined associations between biomarkers, cognition, and NPS.
Results:
Higher P-tau181 (unstandardised beta [B] = −0.10, 95% confidence interval = [−0.20, −0.01]) and T-tau (B = −0.06 [−0.13, −0.01]) levels were associated with poorer memory recall in participants with YOD. In non-AD dementias, higher T-tau levels predicted greater NPS severity (B = 0.76 [0.06, 3.52]). NfL showed no significant associations with NPS or cognition.
Conclusion:
Tau-related neurodegeneration (P-tau181 and T-tau) appears more closely linked to memory impairment in YOD than axonal injury markers such as NfL. In non-AD dementias, T-tau was additionally associated with behavioural symptom severity, suggesting tau-related mechanisms across subtypes. These associations require validation in larger, longitudinal, and multimodal studies to clarify temporal and mechanistic pathways.
Half a century of neuroimaging has transformed our understanding of psychiatric disorders but not our clinical practice. This piece examines why that promise remains unfulfilled and argues that the future lies not in ever newer tools but in rigorous, mechanistically grounded and clinically embedded imaging approaches that bridge brains, behaviours and treatments.
This chapter provides an overview of chronic traumatic encephalopathy (CTE), a neurodegenerative disease associated with repetitive head trauma. It discusses the historical background of CTE, its neuropathology, clinical features, and epidemiology. The chapter also explores the current understanding of CTE staging and common co-pathologies. It highlights the challenges in diagnosing and monitoring CTE in living patients and the ongoing research efforts to develop biomarkers for early detection. The chapter concludes by discussing the prevention, treatment, and future directions in CTE research. It is important to recognize the risks of head trauma and implement measures to reduce the incidence of CTE and other neurodegenerative diseases associated with head trauma.
Mild cognitive impairment (MCI) is a clinical syndrome characterized by cognitive changes from previous levels of performance, often seen as a transitional state between normal aging and dementia. It can be caused by various factors such as Alzheimer’s disease, Lewy body disorders, vascular disease, and other neurodegenerative conditions. The prevalence of MCI increases with age, and the progression rate to dementia is approximately 15-20% per year. Pharmacologic treatments for MCI, particularly those targeting Alzheimer’s disease, have limited efficacy. Non-pharmacologic interventions like aerobic exercise and cognitive stimulation may have some benefits. Biomarkers, particularly plasma markers, are being used to diagnose and predict the progression of MCI to dementia. A combination of biomarkers like P-tau 181 and NfL has shown promise in predicting progression. MCI remains a useful construct in clinical practice and research for identifying individuals at risk of cognitive decline and dementia.
The behavioral variant of frontotemporal dementia (bvFTD) is a clinical syndrome characterized by progressive deterioration of social behavior and cognitive functions. It is one of the most common causes of early-onset dementia and is associated with frontotemporal lobar degeneration (FTLD). The diagnosis of bvFTD can be challenging due to its overlap with other psychiatric disorders, but obtaining a detailed clinical history from a reliable informant is essential. Diagnostic criteria for bvFTD include behavioral and cognitive features such as loss of motivation, social disinhibition, lack of empathy, repetitive behaviors, changes in eating habits, and executive dysfunction. Biomarkers such as brain imaging and genetic testing can help increase diagnostic certainty. Disease progression in bvFTD leads to disability and functional deterioration. Future research aims to improve early recognition, diagnostic accuracy, and the development of disease-modifying treatments.
Prion diseases (PrDs) are a group of uniformly fatal neurodegenerative diseases that affect humans and other mammals. At a molecular level, all PrDs are caused by the misfolding of the normal prion protein (PrPC, in which C stands for the normal cellular form) into an abnormal, misfolded form called the prion or PrPSc (in which Sc stands for the scrapie, the prion disease of sheep and goats). Progressive misfolding of prion proteins and spread of prions in the brain lead to unique pattern of neurodegeneration (1). Clinically, the molecular and neuropathological changes lead to protean neurobehavioral manifestations in humans (2, 3). Most cases of human prion disease (hPrD) develop sporadically and are called sporadic Creutzfeldt-Jakob disease (sCJD), but there are also genetic (often familial) forms, and very rarely acquired forms (aCJD) from iatrogenic (i.e., iCJD) or environmental exposure to tissues infected with prions (1). The main objective of this chapter is to provide a clinical description of these three forms of hPrD.
Biomarkers are objectively measured characteristics of a biologic or pathogenic process, which can have a variety of applications, including diagnosing disease and measuring response to therapeutic interventions. Historically, the diagnosis of dementing neurodegenerative diseases has relied on clinical characterization of patients during life, using established clinical diagnostic criteria to assign the diagnosis that best matches the patient’s phenotype, and later performing postmortem brain autopsy to make a definitive diagnosis. Biomarkers have been developed to measure pathophysiological changes that are hallmarks of different neurodegenerative diseases. For example, in Alzheimer’s disease (AD), biomarkers can detect and measure the two pathological hallmarks, amyloid plaques and tau tangles, in living people, using PET, CSF, or plasma testing. Biomarkers have the potential to redefine the diagnosis of AD and neurodegenerative diseases as biological processes rather than as clinical entities. Biomarkers will transform our ability to evaluate and treat neurodegenerative diseases by improving diagnostic accuracy.
Alzheimer’s disease typically manifests age 65 or older with a predominant memory dysfunction followed by a progressive impairment of other cognitive domains. Aging is the main risk factor for AD development. However, up to 10% of patients present an early onset (under 65), manifesting more frequently with atypical phenotypes. Amyloid plaques and neurofibrillary tangles due to tau deposition are the main hallmarks of the disease. Despite sharing the same neuropathological features, AD phenotypes present differential tau distribution patterns in cortical areas, being tau-pathology topographically related to the clinical syndrome. In addition to aging, several other factors may contribute to AD pathology and its clinical expression. AD is currently understood as a disease continuum starting with a preclinical phase, progressively leading to mild cognitive impairment and dementia. The development of biological and neuroimaging biomarkers detecting in vivo the defining features of AD has remarkably improved the accuracy and early diagnosis of AD in the last decades.
There is no recognised cure or specific biomarker for autism spectrum disorder (ASD). Exosomes are small vesicles that carry proteins, lipids and nucleic acids. They have been investigated for diseases such as Parkinson’s and Alzheimer’s. As the conclusions were on the biological utility of exosomes as a non-invasive brain biopsy, some animal, human and in vitro exosome studies have also been presented in the ASD field. The purpose of this review is to compile the studies that have established a relationship between ASD and exosomes so far and discuss their potential for linking the gap between the laboratory and clinic.
Methods:
In this systematic review, 31 PubMed articles were identified using the keywords ‘exosomal’, ‘exosome and ‘autism spectrum disorder’. After excluding 16 reviews, 4 irrelevant studies and 1 preprint, and adding 5 relevant articles, 15 research articles were included based on PRISMA criteria. The articles were investigated and reviewed by both authors. Their methodology and results are also discussed according to two main streams in studies.
Results:
Numerous studies have identified potential biomarkers, including mitochondrial DNA (mtDNA7S), cytokines including IL-1β, TNF-α and IL-6, and different types of RNAs by comparing the exosomal contents of ASD patients or models with controls. In studies that focused on treatment, behavioural improvements were shown in ASD model mice.
Conclusion:
Since there are presently no reliable biomarkers or effective treatments for ASD, exosome-based research offers a promising avenue for early diagnosis and the creation of tailored therapies.
Contrary to the negative acute-phase protein (APP) response, there is no consistent correlation between serum pentameric C-reactive protein (pCRP) and major depression (MDD). Monomeric CRP (mCRP), a dissociation product of pCRP under immune-inflammatory conditions, exhibits pro-inflammatory effects; however, it has not been investigated in MDD or its subtypes, major dysmood disorder (MDMD) and simple dysmood disorder (SDMD).
Objective:
To examine serum mCRP, albumin, transferrin, M1 macrophage and Thelper-17 immune profiles, and adverse childhood experiences (ACEs) in MDD, MDMD and SDMD.
Methods:
Seventy-nine MDMD patients, 30 SDMD patients, and 40 controls were included. Serum mCRP was measured by ELISA; albumin, transferrin, and pCRP by biochemical assays; and cytokines using Luminex technology.
Results:
MDMD patients showed significantly higher mCRP compared with SDMD and controls, while both patient groups exhibited reduced albumin and transferrin. Combining mCRP with albumin and transferrin showed an adequate accuracy for MDD (area under the ROC Curve = 0.793). Adding IL-17A and ACEs improved accuracy (ROC = 0.855). Serum mCRP levels are additionally associated with pCRP, M1 macrophage profile, body mass index, and ACEs. Up to 36.6% of the variance in overall severity of depression was explained by mCRP, T-helper-17 profile, ACEs (all positively), albumin and transferrin (both inversely).
Conclusion:
Future research in MDD should employ mCRP rather than pCRP as a biomarker of depression/MDMD. Combining mCRP with biomarkers of the negative acute-phase response identified 63.7% of MDD patients with a smouldering acute-phase response, with a specificity of 82.1%. We recommend to assess mCRP rather than pCRP in MDD studies.