Florey Department of Neuroscience and Mental Health - Research Publications
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ItemLower levels of soluble β-amyloid precursor protein, but not β-amyloid, in the frontal cortex in schizophrenia(Elsevier, 2024-01)We identified a sub-group (25%) of people with schizophrenia (muscarinic receptor deficit schizophrenia (MRDS)) that are characterised because of markedly lower levels of cortical muscarinic M1 receptors (CHRM1) compared to most people with the disorder (non-MRDS). Notably, bioinformatic analyses of our cortical gene expression data shows a disturbance in the homeostasis of a biochemical pathway that regulates levels of CHRM1. A step in this pathway is the processing of β-amyloid precursor protein (APP) and therefore we postulated there would be altered levels of APP in the frontal cortex from people with MRDS. Here we measure levels of CHRM1 using [3H]pirenzepine binding, soluble APP (sAPP) using Western blotting and amyloid beta peptides (Aβ1-40 and Aβ1-42) using ELISA in the frontal cortex (Brodmann's area 6: BA 6; MRDS = 14, non-MRDS = 14, controls = 14). We confirmed the MRDS cohort in this study had the expected low levels of [3H]pirenzepine binding. In addition, we showed that people with schizophrenia, independent of their sub-group status, had lower levels of sAPP compared to controls but did not have altered levels of Aβ1-40 or Aβ1-42. In conclusion, whilst changes in sAPP are not restricted to MRDS our data could indicate a role of APP, which is important in axonal and synaptic pruning, in the molecular pathology of the syndrome of schizophrenia.
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ItemNo Preview AvailableCerebrospinal fluid neurofilament light chain differentiates behavioural variant frontotemporal dementia progressors from ‘phenocopy’ non‐progressors(Wiley, 2022-12)Background Distinguishing behavioural variant frontotemporal dementia (bvFTD) from non‐neurodegenerative ‘non‐progressor’, ‘phenocopy’ mimics of frontal lobe dysfunction, can be one of the most challenging clinical dilemmas. A biomarker of neuronal injury, neurofilament light chain (NfL), could reduce misdiagnosis and delay. Method Cerebrospinal fluid (CSF) NfL, amyloid beta 1‐42 (AB42), total and phosphorylated tau (T‐tau, P‐tau) levels were examined in patients with an initial diagnosis of bvFTD. Based on follow up information, patients were categorised as Progressors. Non‐Progressors were subtyped in to Phenocopy Non‐Progressors (non‐neurological/neurodegenerative final diagnosis), and Static Non‐Progressors (static deficits, not fully explained by non‐neurological/neurodegenerative causes). Result Forty‐three patients were included: 20 Progressors, 23 Non‐Progressors (15 Phenocopy, 8 Static), 20 controls. NfL concentrations were lower in Non‐Progressors (Non‐Progressors Mean, M=554pg/mL, 95%CI:[461, 675], Phenocopy Non‐Progressors M=459pg/mL, 95%CI:[385, 539], Static Non‐Progressors M=730pg/mL, 95%CI:[516, 940]), compared to bvFTD Progressors (M=2397pg/mL, 95%CI:[1607, 3332]). NfL distinguished Progressors from Non‐Progressors with the highest accuracy (area under the curve 0.92, 90%/87% sensitivity/specificity, 86%/91% positive/negative predictive value, 88% accuracy). Static Non‐Progressors tended to have higher T‐tau and P‐tau levels compared to Phenocopy Non‐Progressors. Conclusion This study demonstrated strong diagnostic utility of CSF NfL in distinguishing bvFTD from phenocopy non‐progressor variants, at baseline, with high accuracy, in a real‐world clinical setting. This has important clinical implications to improve outcomes for patients and clinicians facing this challenging clinical dilemma, as well as for healthcare services, and clinical trials. Further research is required to investigate heterogeneity within the non‐progressor group and potential diagnostic algorithms, and prospective studies are underway assessing plasma NfL.
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ItemNo Preview AvailablePlasma pTau181/Aβ42 identifies cognitive change earlier than CSF pTau181/Ab42(Wiley Open Access, 2022-12)Background Plasma biomarkers now show an accuracy in detecting Amyloid Beta (Aβ) similar to AD biomarkers derived from cerebral spinal fluid (CSF). However, the ability of plasma AD biomarkers, alone or in combination, to predict cognitive decline has not yet been compared to that of CSF AD biomarkers. Method Plasma biomarker data from 233 participants’ first visit in the Australian Imaging, Biomarkers and Lifestyle study (AIBL) was submitted to linear mixed effects models (LME) to quantify the relationship with change in cognition (measured using the AIBL PACC) and in clinical disease stage (CDR SoB) in both PET Aβ‐ (Centiloid value <20CL) and Aβ+ (Centiloid value ≥20CL) participant subgroups. Separate models were used to assess CSF (Elecsys) and plasma (ADx NeuroSciences) data for Aβ42, pTau181 and the pTau181/Aβ42 ratio. Biomarker values were classified into low vs high levels based on ROC‐derived thresholds optimizing separation of PET Aβ status (low vs high at 20 CL). Changes in cognitive and clinical symptoms were then compared between the low/high plasma biomarker groups. Result In Aβ‐ participants, no significant interactions between binary biomarker classification and time were observed for AIBL PACC or CDR SoB, for either CSF or plasma biomarkers. In the Aβ+ participants, interactions between the binary plasma biomarker classification and change in cognition were greater in magnitude that those detected for CSF biomarker classification. For plasma, abnormally high values of both pTau181 and the pTau181/Aβ42 ratio predicted a significant increase over time in CDR SoB (Figure 1H & 1L) and a significant decrease over time in the AIBL PACC score (Figure 1F & 1J), compared the group with low values on the same biomarkers. In cognitively unimpaired Aβ‐ participants, the AIBL PACC score declined in those with abnormally high values of the pTau181 and the pTau181/Aβ42 ratio (Figure 1F & 1J). Conclusion Assays to measure pTau181 and Aβ42 in the plasma possess an accuracy equivalent to those derived from CSF. In particular, abnormally high levels of plasma pTau181 or the ratio of pTau181 to Aβ42 ratio provide a strong prediction of early cognitive changes, even in those with normal PET Aβ status.
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ItemNo Preview AvailablePlasma neurofilament light chain and phosphorylated tau 181 in neurodegenerative and psychiatric disorders: moving closer towards a simple diagnostic test like a 'C‐reactive protein' for the brain?(Wiley, 2021-12)Abstract Background Accurate, timely diagnosis of neurodegenerative disorders, in particular distinguishing primary psychiatric from neurological disorders and in younger people, can be challenging. There is a need for biomarkers to reduce the diagnostic odyssey and improve outcomes. Neurofilament light (NfL) has shown promise as a diagnostic biomarker in a wide range of disorders. Our Markers in Neuropsychiatric Disorders (MiND) Study builds on our pilot (Eratne et al, ANZJP, 2020), to explore the diagnostic and broader utility of plasma and cerebrospinal fluid (CSF) NfL and other novel markers such as phosphorylated tau 181 (p‐tau181), in a broad range of psychiatric and neurodegenerative/neurological disorders, with a view of translation into routine clinical practice. Methods We assessed plasma and/or CSF NfL and p‐tau181 concentrations in broad cohorts, including: patients assessed for neurocognitive/psychiatric symptoms at Neuropsychiatry and Melbourne Young‐Onset Dementia services and other services, in a wide range of disorders including Alzheimer disease, frontotemporal dementia, schizophrenia, bipolar disorder, depression, Niemann‐Pick Type C, epilepsy, functional neurological disorders. The most recent primary consensus diagnosis informed by established diagnostic criteria was categorised: primary psychiatric disorder (PPD), neurodegenerative/neurological disorder (ND), or healthy controls (HC). Results Findings from over 500 patients/participants will be presented, which indicate that CSF and plasma NfL levels are significantly elevated in a broad range of ND compared to a broad range of PPD, and HC, and bvFTD progressors from phenocopy syndromes, differentiating with areas under the curve of >0.90, sensitivity and specificity >90%. Plasma P‐tau181 levels distinguished Alzheimer disease (mainly younger sporadic), compared to other neurodegenerative disorders, with AUC 0.90, 90% sensitivity and specificity. As recruitment, sample analysis, data collection is ongoing, the most up to date results will be presented. Conclusions NfL shows great promise as a diagnostic test to assist with the common, challenging diagnostic dilemma of distinguishing neurodegenerative from non‐neurodegenerative and primary psychiatric disorders. Plasma p‐tau181 shows strong diagnostic utility in younger‐onset Alzheimer disease. A significantly elevated NfL in someone with a psychiatric diagnosis should prompt consideration of neurodegenerative differentials. Plasma NfL could dramatically alter clinical care of patients with neuropsychiatric and neurological symptoms, improving outcomes for patients, their families, the healthcare system, and clinical trials.
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ItemNo Preview AvailableCould cerebrospinal fluid neurofilament light chain reduce misdiagnosis in neurodegenerative and neuropsychiatric disorders in a real‐world setting? A retrospective clinical and diagnostic utility study(Wiley, 2021-12)Abstract Background Patients presenting with neuropsychiatric symptoms often face significant diagnostic odyssey. Our recent research (Eratne et al, ANZJP, 2020) found neurofilament light (NfL) differentiated between neurodegenerative and psychiatric disorders, with high accuracy. Yet the clinical utility of NfL, as to whether it can aid clinicians in avoiding misdiagnosis in a real‐world clinical setting, is unknown. Our primary aim was to measure the rates of diagnostic change in patients with neuropsychiatric symptoms assessed at a tertiary multidisciplinary service, and determine whether baseline cerebrospinal (CSF) NfL level could have prevented misdiagnoses, by predicting the final diagnosis after follow up. Methods We conducted a retrospective file review of patients assessed at an Australian neuropsychiatry and young‐onset dementia service between 2009‐2020. NfL levels were measured from CSF collected at their baseline assessment. Blinded investigators (MK, HD, DE) extracted clinical data including diagnoses from discharge summaries and outpatient letters from the initial assessment and re‐assessment. Baseline and final diagnoses were categorised as neurodegenerative disorder [ND], or, other non‐neurodegenerative conditions including primary psychiatric disorder [Other/PPD]. We also obtained follow‐up information on patients that were subsequently seen at external services where available. Results From a preliminary analysis of those with follow‐up information for at least a year (N=32), six patients’ diagnostic categories (19%) were revised (ND to Other/PPD=5; Other/PPD to ND=1). In all six cases (figure 2), baseline CSF NfL levels, using our previously established cut‐off, would have predicted the final revised diagnosis. As this study is underway, findings for over 200 patients will be presented for the Conference. Conclusions In a real‐world tertiary clinical setting, baseline CSF NfL would have accurately predicted diagnostic change, showing promise to aid clinicians assessing patients with neuropsychiatric symptoms, and reduce misdiagnosis. An elevated level could help exclude primary psychiatric provisional or differential diagnoses, and prompt assertive investigations for neurological and neurodegenerative causes. Conversely, a low NfL, could reassure against a neurodegenerative disorder, preventing unnecessary assessments. Timely and accurate diagnosis will reduce uncertainty, enable early care planning, reduce patient and carer burden, thus improving outcomes and the diagnostic odyssey faced by patients and families.
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ItemNo Preview AvailableClinical reporting following the quantification of cerebrospinal fluid biomarkers in Alzheimer's disease: An international overview(Wiley, 2021-12)Abstract Background The quantification of cerebrospinal fluid (CSF) biomarkers (Amyloid beta peptides [Aß1‐40 and Aß1‐42], t‐tau and p‐tau(181)) is progressively implemented in specialized laboratories as an aid for the multidisciplinary diagnosis of Alzheimer’s disease (AD). There is however a diversity of practices between centers related to pre‐analytical and analytical conditions, the calculation of ratios between analytes, the applied cut‐off, or the use of interpretation scales. Finally, for the same biochemical profile, the interpretation and reporting of results may differ from one center to another, which may raise questions about the commutability of the tests. So far, no consensus has been reached between the different laboratories involved to define the most appropriate conclusions/comments based on the profile of the quantified biomarkers. This work is an essential step towards a consensual harmonization of clinical reporting after CSF analysis in the context of AD diagnosis, as advocated by the "Biofluid Based Biomarkers PIA" working group of the Alzheimer's Association. Method We obtained, by means of a questionnaire, a description of the pre‐analytical and analytical protocols and examples of reporting from 40 centers located in 15 countries, i.e. in the majority of countries that have implemented clinical CSF tests for the diagnosis of AD. We then adopted a consensus approach to propose harmonized comments corresponding to different AD CSF biomarker profiles observed in patients. Result Pre‐analytical procedures were very similar, among the centers. Regarding the analytical part, more than 88% of the laboratories use automatized immunoassays and more than 83% measure Aß1‐40 and compute the Aß1‐42/Aß1‐40 ratio, in addition to the three core biomarkers (Aß1‐42, t‐tau and p‐tau(181)). The cut‐off values of biomarkers used by the different laboratories are widely dispersed. Delay before sending back the results is lower than 1 week in more than 34% of the laboratories. Conclusion Our results highlight the state of the art in terms of clinical CSF analysis in the context of AD. Harmonization of clinical reporting between different centers could benefit AD care, prevention and treatment strategies, as a common terminology will allow a better assessment of the prevalence of AD and the contribution of biochemical biomarkers to its diagnosis.
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ItemNo Preview AvailableCerebrospinal fluid neurofilament light predicts longitudinal diagnostic change in patients with psychiatric and neurodegenerative disorders(CAMBRIDGE UNIV PRESS, 2024-02)OBJECTIVE: People with neuropsychiatric symptoms often experience delay in accurate diagnosis. Although cerebrospinal fluid neurofilament light (CSF NfL) shows promise in distinguishing neurodegenerative disorders (ND) from psychiatric disorders (PSY), its accuracy in a diagnostically challenging cohort longitudinally is unknown. METHODS: We collected longitudinal diagnostic information (mean = 36 months) from patients assessed at a neuropsychiatry service, categorising diagnoses as ND/mild cognitive impairment/other neurological disorders (ND/MCI/other) and PSY. We pre-specified NfL > 582 pg/mL as indicative of ND/MCI/other. RESULTS: Diagnostic category changed from initial to final diagnosis for 23% (49/212) of patients. NfL predicted the final diagnostic category for 92% (22/24) of these and predicted final diagnostic category overall (ND/MCI/other vs. PSY) in 88% (187/212), compared to 77% (163/212) with clinical assessment alone. CONCLUSIONS: CSF NfL improved diagnostic accuracy, with potential to have led to earlier, accurate diagnosis in a real-world setting using a pre-specified cut-off, adding weight to translation of NfL into clinical practice.
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ItemCerebrospinal fluid neurofilament light and cerebral atrophy in younger-onset dementia and primary psychiatric disorders(WILEY, 2023-09)BACKGROUND AND AIMS: Neurodegeneration underpins the pathological processes of younger-onset dementia (YOD) and has been implicated in primary psychiatric disorders (PSYs). Cerebrospinal fluid (CSF) neurofilament light (NfL) has been used to investigate neurodegeneration severity through correlation with structural brain changes in various conditions, but has seldom been evaluated in YOD and PSYs. METHODS: This retrospective study included patients with YOD or PSYs with magnetic resonance imaging (MRI) of the brain and CSF NfL analysis. Findings from brain MRI were analysed using automated volumetry (volBrain) to measure white matter (WM), grey matter (GM) and whole brain (WB) volumes expressed as percentages of total intracranial volume. Correlations between NfL and brain volume measurements were computed whilst adjusting for age. RESULTS: Seventy patients (47 with YOD and 23 with PSY) were identified. YOD types included Alzheimer disease and behavioural variant frontotemporal dementia. PSY included schizophrenia and major depressive disorder. MRI brain sequences were either fast spoiler gradient-echo (FSPGR) or magnetization-prepared rapid acquisition gradient-echo (MPRAGE). In the total cohort, higher NfL was associated with reduced WB in the FSPGR and MPRAGE sequences (r = -0.402 [95% confidence interval (CI), -0.593 to -0.147], P = 0.008 and r = -0.625 [95% CI, -0.828 to -0.395], P < 0.001, respectively). Higher NfL was related to reduced GM in FSPGR (r = 0.385 [95% CI, -0.649 to -0.014], P = 0.017) and reduced WM in MPRAGE (r = -0.650 [95% CI, -0.777 to -0.307], P < 0.001). Similar relationships were seen in YOD, but not in PSY. CONCLUSION: Higher CSF NfL is related to brain atrophy in YOD, further supporting its use as a nonspecific marker of neurodegeneration severity.
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ItemPlasma p-tau181/Aβ1-42 ratio predicts Aβ-PET status and correlates with CSF-p-tau181/Aβ1-42 and future cognitive decline(WILEY, 2022)BACKGROUND: In Alzheimer's disease (AD), plasma amyloid beta (Aβ)1-42 and phosphorylated tau (p-tau) predict high amyloid status from Aβ positron emission tomography (PET); however, the extent to which combination of these plasma assays can predict remains unknown. METHODS: Prototype Simoa assays were used to measure plasma samples from participants who were either cognitively normal (CN) or had mild cognitive impairment (MCI)/AD in the Australian Imaging, Biomarkers and Lifestyle (AIBL) study. RESULTS: The p-tau181/Aβ1-42 ratio showed the best prediction of Aβ-PET across all participants (area under the curve [AUC] = 0.905, 95% confidence interval [CI]: 0.86-0.95) and in CN (AUC = 0.873; 0.80-0.94), and symptomatic (AUC = 0.908; 0.82-1.00) adults. Plasma p-tau181/Aβ1-42 ratio correlated with cerebrospinal fluid (CSF) p-tau181 (Elecsys, Spearman's ρ = 0.74, P < 0.0001) and predicted abnormal CSF Aβ (AUC = 0.816; 0.74-0.89). The p-tau181/Aβ1-42 ratio also predicted future rates of cognitive decline assessed by AIBL Preclinical Alzheimer Cognitive Composite or Clinical Dementia Rating Sum of Boxes (P < 0.0001). DISCUSSION: Plasma p-tau181/Aβ1-42 ratio predicted both Aβ-PET status and cognitive decline, demonstrating potential as both a diagnostic aid and as a screening and prognostic assay for preclinical AD trials.
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ItemNo Preview AvailablePlasma neurofilament light chain protein is not increased in treatment-resistant schizophrenia and first-degree relatives(SAGE PUBLICATIONS LTD, 2022-10)OBJECTIVE: Schizophrenia, a complex psychiatric disorder, is often associated with cognitive, neurological and neuroimaging abnormalities. The processes underlying these abnormalities, and whether a subset of people with schizophrenia have a neuroprogressive or neurodegenerative component to schizophrenia, remain largely unknown. Examining fluid biomarkers of diverse types of neuronal damage could increase our understanding of these processes, as well as potentially provide clinically useful biomarkers, for example with assisting with differentiation from progressive neurodegenerative disorders such as Alzheimer and frontotemporal dementias. METHODS: This study measured plasma neurofilament light chain protein (NfL) using ultrasensitive Simoa technology, to investigate the degree of neuronal injury in a well-characterised cohort of people with treatment-resistant schizophrenia on clozapine (n = 82), compared to first-degree relatives (an at-risk group, n = 37), people with schizophrenia not treated with clozapine (n = 13), and age- and sex-matched controls (n = 59). RESULTS: We found no differences in NfL levels between treatment-resistant schizophrenia (mean NfL, M = 6.3 pg/mL, 95% confidence interval: [5.5, 7.2]), first-degree relatives (siblings, M = 6.7 pg/mL, 95% confidence interval: [5.2, 8.2]; parents, M after adjusting for age = 6.7 pg/mL, 95% confidence interval: [4.7, 8.8]), controls (M = 5.8 pg/mL, 95% confidence interval: [5.3, 6.3]) and not treated with clozapine (M = 4.9 pg/mL, 95% confidence interval: [4.0, 5.8]). Exploratory, hypothesis-generating analyses found weak correlations in treatment-resistant schizophrenia, between NfL and clozapine levels (Spearman's r = 0.258, 95% confidence interval: [0.034, 0.457]), dyslipidaemia (r = 0.280, 95% confidence interval: [0.064, 0.470]) and a negative correlation with weight (r = -0.305, 95% confidence interval: [-0.504, -0.076]). CONCLUSION: Treatment-resistant schizophrenia does not appear to be associated with neuronal, particularly axonal degeneration. Further studies are warranted to investigate the utility of NfL to differentiate treatment-resistant schizophrenia from neurodegenerative disorders such as behavioural variant frontotemporal dementia, and to explore NfL in other stages of schizophrenia such as the prodome and first episode.