Biomarker and pathology studies in neurodegenerative cognitive impairment

Background: Dementia is a major cause of functional impairment and early death in older age groups. Neurodegenerative disorders are the most common cause of dementia. The most frequent neuropathological lesions include neurofibrillary tangles and senile plaques, hallmark lesions for Alzheimer´s disease (AD), and Lewy body pathology, which characterize Lewy body disease (LBD). Clinically, the neuropathological entity LBD can present as either Parkinson´s disease (PD) or dementia with Lewy bodies (DLB), differentiated on the basis of the presenting symptoms being either motor or cognitive. While the majority of LBD patients develop both motor symptoms and cognitive impairment, some patients with clinical PD will never experience cognitive impairment and likewise some patients with DLB will never develop motor symptoms. Similarly the clinical presentation of AD is also heterogeneous, for instance, the highly variable occurrence of neuropsychiatric symptoms and rate of progression. These differences have a major impact on quality of life for patients and carers, as well as health care costs, but their mechanisms and neuropathological underpinnings are poorly understood. Furthermore the correlation between clinical diagnosis and neuropathological findings is relatively low, and LBD patients presenting with cognitive impairment particularly risk being misclassified as AD. This highlight the need for more precise biomarkers for these clinical syndromes that can be implemented at the start of and during the course of the disease. Biomarkers may inform about disease pathology, thus paving the way for new treatment, they increase diagnostic accuracy and aid in setting a prognosis. Biomarkers are needed in the selection of patients for treatment studies and to identify which patients should benefit from new treatment when available. The cerebrospinal fluid (CSF) biomarkers beta-amyloid 42 (abeta42), total tau (t-tau) and tau protein phosphorylated at amino acid 181 (p-tau181) reflect key AD pathologies. The Lewy bodies found in LBD are composed mainly of the protein !-synuclein. !-synuclein is reduced in CSF in LBD, but with considerable overlap between LBD, controls and other disease groups. Aim: The main aim of this thesis was to increase understanding of pathological mechanisms underlying important clinical features in neurodegenerative cognitive impairment, by exploring the associations between clinical presentation and biomarkers and pathology. The first objective was to explore the association between AD pathology CSF markers and neuropsychiatric symptoms in newly diagnosed AD patients; secondly to assess the association between CSF markers of AD and LBD pathology and early cognitive impairment in PD; thirdly to examine the correlation between clinical diagnosis of DLB and Lewy body pathology at autopsy. Methods: This is a clinical translational neuroscience project based on two clinical cohort studies. The dementia Study of Western Norway (Demvest) included newly diagnosed dementia patients from specialist clinics in geriatric medicine and old age psychiatry in Western Norway. The Parkinson´s Progression Markers Initiative (PPMI) is an international multicentre study, including newly diagnosed PD patients and healthy controls. A comprehensive battery of neuropsychological tests, a structured neuropsychiatric evaluation, clinical examination, and imaging were part of both studies. CSF sampling was done according to standardized protocols and CSF was analysed using commercially available immunoassays. In the Demvest study, participants were recruited for brain donation, and autopsy results were obtained applying commonly used neuropathological protocols and diagnostic criteria. Results: We undertook three specific studies to investigate objective I, II and III. In study I, apathy in patients with early Alzheimer´s disease correlated with t-tau and ptau181 concentrations in CSF, higher values being associated with more severe apathy. There were no associations between depression or psychosis and agitation and CSF markers. In study II, decreased CSF !-synuclein in newly diagnosed PD-patients without dementia correlated with impaired global cognition and impairment of executive functions and attention. CSF abeta42 was decreased in PD with mild cognitive impairment compared with controls after adjusting for covariates. No correlations were found between memory or visuospatial functions and CSF markers. Study III examined autopsy results of 56 patients followed from dementia diagnosis to death. 20 patients received a pathological diagnosis of LBD; the corresponding clinical diagnosis were probable DLB (n=11), Parkinson´s disease with dementia (PDD) (n=5) and probable or possible AD (n=4). Of the 56, 14 patients received a clinical diagnosis of probable DLB, 11 of these had pathological LBD and three AD. Sensitivity, specificity, positive and negative predictive values of a clinical DLB diagnosis were 73%, 93%, 70%, and 90% respectively. Conclusions and implications: We have reported a novel association between neuropsychiatric symptoms and CSF biomarkers reflecting core AD pathology. The relationship between t-tau and p-tau181 and apathy may reflect an association between neurofibrillary tangle pathology and apathy in early AD. Cognitive impairment in early PD was associated with biomarkers of both Lewy body and AD pathology. 18 of 20 LBD patients in the Demvest study had Braak neurofibrillary tangle stage IV or higher, representing severe AD pathology at autopsy. Thus our findings suggest a role for AD pathology in both early and established LBD. Accurate diagnosis is crucial for clinical practice and research. With a sensitivity of 73%, the clinical 2005 DLB criteria are not sensitive enough. More than one in four DLB patients were not identified even when structured rating scales for core DLB symptoms were applied. We regard a specificity of 93% as satisfactory. Our results illustrate that not all DLB patients fulfil the 2005 DLB criteria at disease presentation, highlighting the need for re-evaluation of the diagnosis if new symptoms appear. Studies applying the most recent 2017 DLB criteria will show if this revision has increased sensitivity without decreasing specificity

Cognitive decline in dementia with Lewy bodies: a 5-year prospective cohort study

OBJECTIVES: We report the cognitive decline in persons diagnosed with mild dementia with Lewy bodies (DLB) and mild Alzheimer's disease (AD) during 5 years of annual follow-ups. METHODS: Patients were recruited into the study from geriatric, psychiatric and neurology clinics in Western Norway during 2005–2013. They were diagnosed according to clinical consensus criteria, based on standardised clinical rating scales. Autopsy-based diagnoses were available for 20 cases. Cognitive decline for up to 5 years was assessed using the Clinical Dementia Rating (CDR) scale and the Mini-Mental State Examination (MMSE). Survival analysis including Cox regression (time to reach severe dementia) and linear mixed-effects (lme) modelling were used to model the decline on MMSE. RESULTS: At least one follow-up assessment was available for 67 patients with DLB and 107 patients with AD, with a median follow-up time of 4.3 years. The time to reach severe dementia was significantly shorter in DLB (median 1793 days) compared with AD (1947 days; p=0.033), and the difference remained significant in the multiple Cox regression analysis (HR=2.0, p<0.02). In the adjusted lme model, MMSE decline was faster in DLB (annual decline 4.4 points) compared with AD (3.2 points; p<0.008). CONCLUSIONS: Our findings show that from the mild dementia stage, patients with DLB have a more rapid cognitive decline than in AD. Such prognostic information is vital for patients and families and crucial for planning clinical trials and enabling health economic modelling

The Scandinavian Small-for-Gestational Age (SGA) pregnancy and birth cohort – A source to continual insight into fetal growth restriction and long term physical and neurodevelopmental health in mother and offspring

Human in utero growth restriction (IUGR) is associated with an increased risk for perinatal mortality and morbidity among newborns and infants. To pursue this challenge, a Request For Proposals (RFP) was issued in 1983 by The U.S. Epidemiology and Biometry Research Program at the National Institute of Child Health and Human Development (NICHD). A consortium was set up at the universities and university hospitals in Trondheim, Bergen (Norway) and Uppsala (Sweden) and was funded by the NICHD to conduct the Scandinavian Successive Small-for-Gestational Age (SGA) pregnancy and birth outcome study. The study design included a comprehensive biobank with maternal and cord serum samples, placental tissue, and a multitude of data collected from interviews, questionnaires, and clinical examinations.  The SGA cohort study involved 6,354 Caucasian pregnant women in the three study sites who expected their second or third child from 1986-88. The study women were screened in early second trimester and mothers who had an increased risk to deliver a smaller than expected newborn were followed in detail through the second half of pregnancy and at birth. Selected children were screened several times through their first and up to five years of age. Moreover, a highly selected subgroup in Trondheim has been followed at 14, 19, and 26 years’ age.  Almost thirty years later, we have searched the body of scientific publications that originated from this cohort study in an attempt to assess if and to what extent the main aims and objectives were achieved and to summarize the overall outcomes. The SGA cohort has resulted in close to 100 published papers in peer reviewed journals and some 40 graduate and undergraduate degrees. Risk factors of SGA, like maternal smoking, low prepregnancy weight and education attainment, and a previous SGA birth outcome were confirmed. Conversely, no totally new and unknown risk factors were identified. Serial ultrasound measures have enabled a distinction between SGA with restricted and normal intrauterine growth, and has further indicated that being born SGA is mainly a problem in combination with IUGR. Further, the consequences of IUGR are more pronounced at adolescence and young adulthood than at five years of age.  An increased understanding of the pathogenesis of different categories of growth restriction is essential to recognize and diagnose IUGR properly, and to reduce the perinatal mortality and morbidity from SGA. Moreover, SGA is a significant predictor at follow-up of the child. An up to date biobank has ensured the quality of data and biological samples, and has been crucial for the outcome of the entire SGA study. It continues to be a valuable resource in future research

Cerebrospinal Fluid Levels of sAPPα and sAPPβ in Lewy Body and Alzheimer's Disease: Clinical and Neurochemical Correlates

We measured cerebrospinal fluid (CSF) levels of the soluble isoforms of amyloid precursor protein (APP; sAPPα sAPPβ) and other CSF biomarkers in 107 patients with Alzheimer's disease (AD), dementia with Lewy body dementia (DLB), Parkinson's disease dementia (PDD), and normal controls (NC) using commercial kits. DLB and PDD were combined in a Lewy body dementia group (LBD). No differences were observed in sAPPα and sAPPβ levels between the groups. Significant correlations were observed between sAPPα and sAPPβ and between sAPPβ and Mini-Mental State Examination scores in the total group analysis as well as when LBD and AD groups were analyzed separately. sAPPα and sAPPβ levels correlated with Aβ38, Aβ40, Aβ42, and Tau in the LBD group. In AD, sAPPα correlated with p-Tau and sAPPβ with Aβ40. The differential association between sAPPα and sAPPβ with Aβ and Tau species between LBD and AD groups suggests a possible relationship with the underlying pathologies in LBD and AD

Inflammatory biomarkers in newly diagnosed patients with Parkinson’s disease and related neurodegenerative disorders

Background and Objectives Neuroinflammation contributes to Parkinson disease (PD) pathology, and inflammatory biomarkers may aid in PD diagnosis. Proximity extension assay (PEA) technology is a promising method for multiplex analysis of inflammatory markers. Neuroinflammation also plays a role in related neurodegenerative diseases, such as dementia with Lewy bodies (DLB) and Alzheimer disease (AD). The aim of this work was to assess the value of inflammatory biomarkers in newly diagnosed patients with PD and in patients with DLB and AD. Methods Patients from the Norwegian ParkWest and Dementia Study of Western Norway longitudinal cohorts (PD, n = 120; DLB, n = 15; AD, n = 27) and 44 normal controls were included in this study. A PEA inflammation panel of 92 biomarkers was measured in the CSF. Disease-associated biomarkers were identified using elastic net (EN) analysis. We assessed the discriminatory power of disease-associated biomarkers using receiver operating characteristic (ROC) curve analysis and estimated the optimism-adjusted area under the curve (AUC) using the bootstrapping method. Results EN analysis identified 9 PEA inflammatory biomarkers (ADA, CCL23, CD5, CD8A, CDCP1, FGF-19, IL-18R1, IL-6, and MCP-2) associated with PD. Seven of the 9 biomarkers were included in a diagnostic panel, which was able to discriminate between those with PD and controls (optimism-adjusted AUC 0.82). Our 7-biomarker PD panel was also able to distinguish PD from DLB and from AD. In addition, 4 inflammatory biomarkers were associated with AD and included in a panel, which could distinguish those with AD from controls (optimism-adjusted AUC 0.87). Our 4-biomarker AD panel was also able to distinguish AD from DLB and from PD. Discussion In our exploratory study, we identified a 7-biomarker panel for PD and a 4-biomarker panel for AD. Our findings indicate potential inflammation-related biomarker candidates that could contribute toward PD-specific and AD-specific diagnostic panels, which should be further explored in other larger cohorts.publishedVersio

Biomarker and pathology studies in neurodegenerative cognitive impairment

Background: Dementia is a major cause of functional impairment and early death in older age groups. Neurodegenerative disorders are the most common cause of dementia. The most frequent neuropathological lesions include neurofibrillary tangles and senile plaques, hallmark lesions for Alzheimer´s disease (AD), and Lewy body pathology, which characterize Lewy body disease (LBD). Clinically, the neuropathological entity LBD can present as either Parkinson´s disease (PD) or dementia with Lewy bodies (DLB), differentiated on the basis of the presenting symptoms being either motor or cognitive. While the majority of LBD patients develop both motor symptoms and cognitive impairment, some patients with clinical PD will never experience cognitive impairment and likewise some patients with DLB will never develop motor symptoms. Similarly the clinical presentation of AD is also heterogeneous, for instance, the highly variable occurrence of neuropsychiatric symptoms and rate of progression. These differences have a major impact on quality of life for patients and carers, as well as health care costs, but their mechanisms and neuropathological underpinnings are poorly understood. Furthermore the correlation between clinical diagnosis and neuropathological findings is relatively low, and LBD patients presenting with cognitive impairment particularly risk being misclassified as AD. This highlight the need for more precise biomarkers for these clinical syndromes that can be implemented at the start of and during the course of the disease. Biomarkers may inform about disease pathology, thus paving the way for new treatment, they increase diagnostic accuracy and aid in setting a prognosis. Biomarkers are needed in the selection of patients for treatment studies and to identify which patients should benefit from new treatment when available. The cerebrospinal fluid (CSF) biomarkers beta-amyloid 42 (abeta42), total tau (t-tau) and tau protein phosphorylated at amino acid 181 (p-tau181) reflect key AD pathologies. The Lewy bodies found in LBD are composed mainly of the protein !-synuclein. !-synuclein is reduced in CSF in LBD, but with considerable overlap between LBD, controls and other disease groups. Aim: The main aim of this thesis was to increase understanding of pathological mechanisms underlying important clinical features in neurodegenerative cognitive impairment, by exploring the associations between clinical presentation and biomarkers and pathology. The first objective was to explore the association between AD pathology CSF markers and neuropsychiatric symptoms in newly diagnosed AD patients; secondly to assess the association between CSF markers of AD and LBD pathology and early cognitive impairment in PD; thirdly to examine the correlation between clinical diagnosis of DLB and Lewy body pathology at autopsy. Methods: This is a clinical translational neuroscience project based on two clinical cohort studies. The dementia Study of Western Norway (Demvest) included newly diagnosed dementia patients from specialist clinics in geriatric medicine and old age psychiatry in Western Norway. The Parkinson´s Progression Markers Initiative (PPMI) is an international multicentre study, including newly diagnosed PD patients and healthy controls. A comprehensive battery of neuropsychological tests, a structured neuropsychiatric evaluation, clinical examination, and imaging were part of both studies. CSF sampling was done according to standardized protocols and CSF was analysed using commercially available immunoassays. In the Demvest study, participants were recruited for brain donation, and autopsy results were obtained applying commonly used neuropathological protocols and diagnostic criteria. Results: We undertook three specific studies to investigate objective I, II and III. In study I, apathy in patients with early Alzheimer´s disease correlated with t-tau and ptau181 concentrations in CSF, higher values being associated with more severe apathy. There were no associations between depression or psychosis and agitation and CSF markers. In study II, decreased CSF !-synuclein in newly diagnosed PD-patients without dementia correlated with impaired global cognition and impairment of executive functions and attention. CSF abeta42 was decreased in PD with mild cognitive impairment compared with controls after adjusting for covariates. No correlations were found between memory or visuospatial functions and CSF markers. Study III examined autopsy results of 56 patients followed from dementia diagnosis to death. 20 patients received a pathological diagnosis of LBD; the corresponding clinical diagnosis were probable DLB (n=11), Parkinson´s disease with dementia (PDD) (n=5) and probable or possible AD (n=4). Of the 56, 14 patients received a clinical diagnosis of probable DLB, 11 of these had pathological LBD and three AD. Sensitivity, specificity, positive and negative predictive values of a clinical DLB diagnosis were 73%, 93%, 70%, and 90% respectively. Conclusions and implications: We have reported a novel association between neuropsychiatric symptoms and CSF biomarkers reflecting core AD pathology. The relationship between t-tau and p-tau181 and apathy may reflect an association between neurofibrillary tangle pathology and apathy in early AD. Cognitive impairment in early PD was associated with biomarkers of both Lewy body and AD pathology. 18 of 20 LBD patients in the Demvest study had Braak neurofibrillary tangle stage IV or higher, representing severe AD pathology at autopsy. Thus our findings suggest a role for AD pathology in both early and established LBD. Accurate diagnosis is crucial for clinical practice and research. With a sensitivity of 73%, the clinical 2005 DLB criteria are not sensitive enough. More than one in four DLB patients were not identified even when structured rating scales for core DLB symptoms were applied. We regard a specificity of 93% as satisfactory. Our results illustrate that not all DLB patients fulfil the 2005 DLB criteria at disease presentation, highlighting the need for re-evaluation of the diagnosis if new symptoms appear. Studies applying the most recent 2017 DLB criteria will show if this revision has increased sensitivity without decreasing specificity

The Scandinavian small-for-gestational age (SGA) pregnancy and birth cohort – A source to continual insight into fetal growth restriction and long term physical and neurodevelopmental health in mother and offspring

Human in utero growth restriction (IUGR) is associated with an increased risk for perinatal mortality and morbidity among newborns and infants. To pursue this challenge, a Request For Proposals (RFP) was issued in 1983 by The U.S. Epidemiology and Biometry Research Program at the National Institute of Child Health and Human Development (NICHD). A consortium was set up at the universities and university hospitals in Trondheim, Bergen (Norway) and Uppsala (Sweden) and was funded by the NICHD to conduct the Scandinavian Successive Small-for-Gestational Age (SGA) pregnancy and birth outcome study. The study design included a comprehensive biobank with maternal and cord serum samples, placental tissue, and a multitude of data collected from interviews, questionnaires, and clinical examinations. The SGA cohort study involved 6,354 Caucasian pregnant women in the three study sites who expected their second or third child from 1986-88. The study women were screened in early second trimester and mothers who had an increased risk to deliver a smaller than expected newborn were followed in detail through the second half of pregnancy and at birth. Selected children were screened several times through their first and up to five years of age. Moreover, a highly selected subgroup in Trondheim has been followed at 14, 19, and 26 years’ age. Almost thirty years later, we have searched the body of scientific publications that originated from this cohort study in an attempt to assess if and to what extent the main aims and objectives were achieved and to summarize the overall outcomes. The SGA cohort has resulted in close to 100 published papers in peer reviewed journals and some 40 graduate and undergraduate degrees. Risk factors of SGA, like maternal smoking, low prepregnancy weight and education attainment, and a previous SGA birth outcome were confirmed. Conversely, no totally new and unknown risk factors were identified. Serial ultrasound measures have enabled a distinction between SGA with restricted and normal intrauterine growth, and has further indicated that being born SGA is mainly a problem in combination with IUGR. Further, the consequences of IUGR are more pronounced at adolescence and young adulthood than at five years of age. An increased understanding of the pathogenesis of different categories of growth restriction is essential to recognize and diagnose IUGR properly, and to reduce the perinatal mortality and morbidity from SGA. Moreover, SGA is a significant predictor at follow-up of the child. An up to date biobank has ensured the quality of data and biological samples, and has been crucial for the outcome of the entire SGA study. It continues to be a valuable resource in future research

Accuracy of Clinical Diagnosis of Dementia with Lewy Bodies versus Neuropathology

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