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Over the past two decades, there has been increasing research into the molecular composition and function of small extracellular vesicles in the central nervous system. This is due in part to the recognition that small extracellular vesicles likely contribute to the pathogenesis of neurological diseases such as Alzheimer’s disease, but also an understanding that small extracellular vesicles are a source of potential biomarkers. Small extracellular vesicles carry specific cargo that reflects their biogenesis and cellular origins, including protein, RNA and lipid. While the protein and RNA content of small extracellular vesicles in the central nervous system diseases and have been studied extensively, our understanding of the lipidome of small extracellular vesicles in the central nervous system is still in its infancy. Lipids play a significant role in maintaining central nervous system structure and function, and the dysregulation of lipid metabolism is known to occur in many neurological disorders, including Alzheimer’s disease. Here we review what is currently known about lipid dyshomeostasis in Alzheimer’s disease. We propose that small extracellular vesicle lipids may provide insight into the pathophysiology and progression of Alzheimer’s disease and other neurological disorders, and, in the future perhaps, aid in disease monitoring and detection.

Background Major prevention trials for Alzheimer’s disease (AD) are now focusing on multidomain lifestyle interventions. However, the exact combination of behavioral factors related to AD pathology remains unclear. In 2 cohorts of cognitively unimpaired individuals at risk of AD, we examined which combinations of personality traits, neuropsychiatric symptoms, and cognitive lifestyle (years of education or lifetime cognitive activity) related to the pathological hallmarks of AD, amyloid-β, and tau deposits. Methods A total of 115 older adults with a parental or multiple-sibling family history of sporadic AD (PREVENT-AD [PRe-symptomatic EValuation of Experimental or Novel Treatments for AD] cohort) underwent amyloid and tau positron emission tomography and answered several questionnaires related to behavioral attributes. Separately, we studied 117 mutation carriers from the DIAN (Dominant Inherited Alzheimer Network) study group cohort with amyloid positron emission tomography and behavioral data. Using partial least squares analysis, we identified latent variables relating amyloid or tau pathology with combinations of personality traits, neuropsychiatric symptoms, and cognitive lifestyle. Results In PREVENT-AD, lower neuroticism, neuropsychiatric burden, and higher education were associated with less amyloid deposition (p = .014). Lower neuroticism and neuropsychiatric features, along with higher measures of openness and extraversion, were related to less tau deposition (p = .006). In DIAN, lower neuropsychiatric burden and higher education were also associated with less amyloid (p = .005). The combination of these factors accounted for up to 14% of AD pathology. Conclusions In the preclinical phase of both sporadic and autosomal dominant AD, multiple behavioral features were associated with AD pathology. These results may suggest potential pathways by which multidomain interventions might help delay AD onset or progression.

Glial fibrillary acidic protein (GFAP) is a promising candidate blood-based biomarker for Alzheimer’s disease (AD) diagnosis and prognostication. The timing of its disease-associated changes, its clinical correlates, and biofluid-type dependency will influence its clinical utility. We evaluated plasma, serum, and CSF GFAP in families with autosomal dominant AD (ADAD), leveraging the predictable age at symptom onset to determine changes by stage of disease. Plasma GFAP elevations appear a decade before expected symptom onset, after β-amyloid accumulation and prior to neurodegeneration and cognitive decline. Plasma GFAP distinguished β-amyloid-positive from β-amyloid-negative ADAD participants and showed a stronger relationship with β-amyloid load in asymptomatic than symptomatic ADAD. Higher plasma GFAP was associated with the degree and rate of neurodegeneration and cognitive impairment. Serum GFAP showed similar relationships, but these were less pronounced for CSF GFAP. Our findings support a role for plasma GFAP as a clinical biomarker for β-amyloid-associated cognitive deterioration in AD.

Normal and pathologic neurobiological processes influence brain morphology in coordinated ways that give rise to structural covariance patterns across brain regions and individuals. We present a mega-analysis of structural covariance with magnetic resonance imaging of 50,699 healthy and diseased individuals (12 studies, 130 sites, and 12 countries) over their lifespan (ages 5 through 97). Patterns of structural covariance (PSC) were highly heritable (0.05< h2 -log10[p-value] > 8.8): 1245 previously unreported, and 69% of them independently replicated (-log10[p-value] = 4.5). Associations revealed an imaging phenotypic landscape between 2003 PSCs and 49 clinical and cognitive traits at multiple scales. We constructed machine learning-derived individualized imaging signatures for various disease diagnoses using PSC features at multiple scales, suggesting that disease effects on the brain were better manifested in a multi-scale continuum than on any single scale. Experimental results were integrated into the Multi-scale Structural Imaging Covariance (MuSIC) atlas and made publicly accessible through the BRIDGEPORT web portal (https://www.cbica.upenn.edu/bridgeport/). Our results reveal strong associations between brain structural covariance, genetics, and clinical phenotypes, supporting that PSCs can serve as an endophenotypic anatomic dictionary in future research.

Important insights into the early pathogenesis of Alzheimer's disease can be provided by studies of autosomal dominant Alzheimer's disease and Down syndrome. However, it is unclear whether the timing and spatial distribution of amyloid accumulation differs between people with autosomal dominant Alzheimer's disease and those with Down syndrome. We aimed to directly compare amyloid changes between these two groups of people.In this cross-sectional study, we included participants (aged ≥25 years) with Down syndrome and sibling controls who had MRI and amyloid PET scans in the first data release (January, 2020) of the Alzheimer's Biomarker Consortium-Down Syndrome (ABC-DS) study. We also included carriers of autosomal dominant Alzheimer's disease genetic mutations and non-carrier familial controls who were within a similar age range to ABC-DS participants (25-73 years) and had MRI and amyloid PET scans at the time of a data freeze (December, 2020) of the Dominantly Inherited Alzheimer Network (DIAN) study. Controls from the two studies were combined into a single group. All DIAN study participants had genetic testing to determine PSEN1, PSEN2, or APP mutation status. APOE genotype was determined from blood samples. CSF samples were collected in a subset of ABC-DS and DIAN participants and the ratio of amyloid β42 (Aβ42) to Aβ40 (Aβ42/40) was measured to evaluate its Spearman's correlation with amyloid PET. Global PET amyloid burden was compared with regards to cognitive status, APOE ɛ4 status, sex, age, and estimated years to symptom onset. We further analysed amyloid PET deposition by autosomal dominant mutation type. We also assessed regional patterns of amyloid accumulation by estimated number of years to symptom onset. Within a subset of participants the relationship between amyloid PET and CSF Aβ42/40 was evaluated.192 individuals with Down syndrome and 33 sibling controls from the ABC-DS study and 265 carriers of autosomal dominant Alzheimer's disease mutations and 169 non-carrier familial controls from the DIAN study were included in our analyses. PET amyloid centiloid and CSF Aβ42/40 were negatively correlated in carriers of autosomal dominant Alzheimer's disease mutations (n=216; r=-0·565; p0·0001) and in people with Down syndrome (n=32; r=-0·801; p0·0001). There was no difference in global PET amyloid burden between asymptomatic people with Down syndrome (mean 18·80 centiloids [SD 28·33]) versus asymptomatic mutation carriers (24·61 centiloids [30·27]; p=0·11) and between symptomatic people with Down syndrome (77·25 centiloids [41·76]) versus symptomatic mutation carriers (69·15 centiloids [51·10]; p=0·34). APOE ɛ4 status and sex had no effect on global amyloid PET deposition. Amyloid deposition was elevated significantly earlier in mutation carriers than in participants with Down syndrome (estimated years to symptom onset -23·0 vs -17·5; p=0·0002). PSEN1 mutations primarily drove this difference. Early amyloid accumulation occurred in striatal and cortical regions for both mutation carriers (n=265) and people with Down syndrome (n=128). Although mutation carriers had widespread amyloid accumulation in all cortical regions, the medial occipital regions were spared in people with Down syndrome.Despite minor differences, amyloid PET changes were similar between people with autosomal dominant Alzheimer's disease versus Down syndrome and strongly supported early amyloid dysregulation in individuals with Down syndrome. Individuals with Down syndrome aged at least 35 years might benefit from early intervention and warrant future inclusion in clinical trials, particularly given the relatively high incidence of Down syndrome.The National Institute on Aging, Riney and Brennan Funds, the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the German Center for Neurodegenerative Diseases, and the Japan Agency for Medical Research and Development.

Nationwide surveillance of human prion diseases (also known as transmissible spongiform encephalopathies), the most common being Creutzfeldt–Jakob disease (CJD), is performed by the Australian National Creutzfeldt–Jakob Disease Registry (ANCJDR), based at the University of Melbourne. National surveillance encompasses the period since 1970, with prospective surveillance occurring from 1993 onwards. Over this prospective surveillance period considerable developments have occurred, especially in relation to pre-mortem diagnostics, the delineation of new disease subtypes and a heightened awareness of prion diseases in the health care setting. The surveillance practices of the ANCJDR have evolved and adapted accordingly. Since the ANCJDR began offering cerebrospinal fluid (CSF) 14-3-3 protein testing in Australia in September 1997, the annual number of referrals has steadily increased to a maximum of 508 in 2017. The number of CSF test referrals in 2017 represents a 20% increase compared to that of 2016. In 2017, there was an overall stabilisation of the annual incidence rate of confirmed prion disease in Australia at expected levels; 72 persons with suspected human prion disease were added to the national register, with 72% of all suspected CJD cases undergoing neuropathological examination. The majority of the 72 suspected cases added to the register are as of 31 December 2017 still classified as “incomplete” (47 cases), while four cases were excluded by either detailed clinical follow-up (1 case) or neuropathological examination (3 cases); 19 cases were classified as definite and two as probable prion disease. No cases of variant CJD (vCJD) were confirmed.

Alzheimer’s Disease (AD) is the most common form of dementia, characterised by extracellular amyloid deposition as plaques and intracellular neurofibrillary tangles of tau protein. As no current clinical test can diagnose individuals at risk of developing AD, the aim of this project is to evaluate a blood-based biomarker panel to identify individuals who carry this risk. We analysed the levels of 22 biomarkers in clinically classified healthy controls (HC), mild cognitive impairment (MCI) and Alzheimer’s participants from the well characterised Australian Imaging, Biomarker and Lifestyle (AIBL) study of aging. High levels of IL-10 and IL-12/23p40 were significantly associated with amyloid deposition in HC, suggesting that these two biomarkers might be used to detect at risk individuals. Additionally, other biomarkers (Eotaxin-3, Leptin, PYY) exhibited altered levels in AD participants possessing the APOE ε4 allele. This suggests that the physiology of some potential biomarkers may be altered in AD due to the APOE ε4 allele, a major risk factor for AD. Taken together, these data highlight several potential biomarkers that can be used in a blood-based panel to allow earlier identification of individuals at risk of developing AD and/or early stage AD for which current therapies may be more beneficial.

Objective: This study investigated the retinal arteriolar central reflex (CR, the central reflection observed in photographs of retinal vessels), which may provide information about micro-vascular health in the retina and also the brain, due to the homology between these vascular networks. The study also describes a novel computer based semi-automated technique that accurately quantifies retinal arteriolar CR and vessel width, and calculates the CR to vessel width ratio (CRR) from digital retinal photographs. Methods: Digital retinal photographs were collected from participants in the Australian Imaging, Biomarkers and Lifestyle study of ageing (AIBL), including 25 participants diagnosed with Alzheimer’s disease (AD) (age 72.4 ± 7.5 yrs, 12 male, 13 female) and 123 elderly participants without dementia (cognitively normals: CN) (age 71.6 ± 5.6 yrs, 55 male, 68 female). Using a sub-cohort of 144 (22 AD, 122 CN) with the novel CRR measures, we identified significantly higher CRR levels in AD participants (mean CRR 0.253 (SD 0.04)) as compared with CN’s (mean CRR 0.231 (SD 0.04), p = 0.025). Adjustment for APOE e4 allele status however, reduced the significance (p = 0.081). CRR was significantly higher in APOE e4 allele carriers (mean CRR 0.254 (SD 0.03) as compared with non-carriers (mean CRR 0.224 (SD 0.05), p < 0.0001). Results: These data indicate that CRR is strongly linked to APOE e4 status and exhibits a weaker, independent trend with AD diagnosis. The retina may be useful as a novel model for non-invasive monitoring of the effects of APOE e4 on the central nervous system, particularly in cerebrovascular disease.

OBJECTIVE: To define a practice guideline for biological treatment of dementias for general practitioners in primary care. METHODS: This paper is a short and practical summary of the World Federation of Biological Psychiatry (WFSBP) guidelines for the Biological treatment of Alzheimer's disease and other dementias for treatment in primary care ( Ihl et al. 2011 ). The recommendations were developed by a task force of international experts in the field and are based on randomized controlled studies. RESULTS: Anti-dementia medications neither cure, nor arrest, or alter the course of the disease. The type of dementia, the individual symptom constellation and the tolerability and evidence for efficacy should determine what medications should be used. In treating neuropsychiatric symptoms, psychosocial intervention should be the treatment of first choice. For neuropsychiatric symptoms, medications should only be considered when psychosocial interventions are not adequate and after cautious risk-benefit analysis. CONCLUSIONS: Depending on the diagnostic entity and clinical presentation different anti-dementia drugs can be recommended. These guidelines provide a practical approach for general practitioners managing dementias.

Despite delirium being described in the Greek literature as far back as 400 bc, current levels of knowledge and practice, in comparison to other medical conditions, lag considerably behind. However, over the past 20 years, there has been signicant progress in the way that we understand, conceptualize and manage delirium (Maclullich et al., 2013).

Background: The Australian Imaging, Biomarkers and Lifestyle (AIBL) flagship study of aging aimed to recruit 1000 individuals aged over 60 to assist with prospective research into Alzheimer's disease (AD). This paper describes the recruitment of the cohort and gives information about the study methodology, baseline demography, diagnoses, medical comorbidities, medication use, and cognitive function of the participants.Methods: Volunteers underwent a screening interview, had comprehensive cognitive testing, gave 80 ml of blood, and completed health and lifestyle questionnaires. One quarter of the sample also underwent amyloid PET brain imaging with Pittsburgh compound B (PiB PET) and MRI brain imaging, and a subgroup of 10% had ActiGraph activity monitoring and body composition scanning.Results: A total of 1166 volunteers were recruited, 54 of whom were excluded from further study due to comorbid disorders which could affect cognition or because of withdrawal of consent. Participants with AD (211) had neuropsychological profiles which were consistent with AD, and were more impaired than participants with mild cognitive impairment (133) or healthy controls (768), who performed within expected norms for age on neuropsychological testing. PiB PET scans were performed on 287 participants, 100 had DEXA scans and 91 participated in ActiGraph monitoring.Conclusion: The participants comprising the AIBL cohort represent a group of highly motivated and well-characterized individuals who represent a unique resource for the study of AD. They will be reassessed at 18-month intervals in order to determine the predictive utility of various biomarkers, cognitive parameters and lifestyle factors as indicators of AD, and as predictors of future cognitive decline.

Alzheimer's disease (AD) is a degenerative brain disorder and is the most common form of dementia. Minimally invasive approaches are required that combine biomarkers to identify individuals who are at risk of developing mild cognitive impairment (MCI) and AD, to appropriately target clinical trials for therapeutic discovery as well as lifestyle strategies aimed at prevention. Buccal mucosa cells from the Australian Imaging, Biomarkers and Lifestyle Flagship Study of Ageing cohort (n=60) were investigated for cytological markers that could be used to identify both MCI and AD individuals. Visual scoring of the buccal cytome demonstrated a significantly lower frequency of basal and karyorrhectic cells in the MCI group compared with controls. A high content, automated assay was developed using laser scanning cytometry to simultaneously measure cell types, nuclear DNA content and aneuploidy, neutral lipid content, putative Tau and amyloid-β (Aβ) in buccal cells. DNA content, aneuploidy, neutral lipids and Tau were similar in all groups. However, there was significantly lower Tau protein in both basal and karyolytic buccal cell types compared with differentiated buccal cells. Aβ, as measured by frequency of cells containing Aβ signal, as well as area and integral of Aβ signal, was significantly higher in the AD group compared with the control group. Buccal cell Aβ was correlated with mini-mental state examination (MMSE) scores (r = -0.436, P=0.001) and several blood-based biomarkers. Combining newly identified biomarkers from buccal cells with those already established may offer a potential route for more specific biomarker panels which may substantially increase the likelihood of better predictive markers for earlier diagnosis of AD.

One of the most rapidly developing areas of organellar biology, and one with major involvements in biochemical pharmacology, is that of peroxisomal function. In this commentary, several recent research findings in this area are described, along with their significance in relation to the metabolism of drugs and xenobiotics. Topics that are covered include the peroxisome proliferation caused by a wide variety of chemical compounds, the metabolic implications of this phenomenon, interactions between peroxisomal transcription factors and the eicosanoids, and the close relationships between peroxisomal metabolism and the control of functional damage caused by oxygen free radicals. Examples are also provided on interactions between peroxisomal function and such diverse drug groupings as analgesics, anti-inflammatories, nutritional ingestants, insecticides, antifungals, herbicides, and plasticisers. It is concluded that the peroxisome plays a central role in the metabolism of many drugs, displays a significant potential in furthering an understanding of pharmacological mechanisms, and is deserving of greater emphasis in future research considerations in this area.

This article reviews the currently available data on the role of peroxisomal function in relation to the processes of cell differentiation and carcinogenesis. In regard to tumourigenesis, both genotoxic and non-genotoxic processes have been considered, and the peroxisomal relationships with these phenomena and with differentiation are described at the level of organelle characteristics, enzyme contents, and the involvement of retinoids, steroid hormones, oxygen free radicals, growth factors, apoptosis, omega-3 polyunsaturated fatty acids and the cellular signalling networks. Overall these data serve to illustrate the unique and distinctive role of the peroxisome in differentiation and carcinogenesis, and point to the advantages of considering the peroxisomal involvement in the holistic context of the differentiation dedifferentiation continuum rather than the narrower focus of non-genotoxic carcinogenesis. The review also outlines the potential for medical benefit arising from a fuller understanding of these peroxisomal affiliations.

In this article, the capabilities of peroxisomal involvement in the gluconeogenetic processes of vertebrate animals are reviewed in the light of recent findings on peroxisomal metabolism and proliferation. It is demonstrated that the participation of this organelle affords the potential of alternative pathways for the conversion of triacylglycerols to glucose, and for the conversion of amino acids and lactate to carbohydrate. Of interest in this connection, too, is that glyoxylate may act as a key intermediate in the gluconeogenetic functions of peroxisomes in both plants and animals. In addition, a close connection between peroxisomal function and the hormonal control of gluconeogenesis has been described, with these interrelationships extending to the associated phenomena of cellular signalling, gene expression, peroxisomal proliferation, and the function of insulin-like growth factors. The metabolic advantages of some of these alternative pathways for gluconeogenesis have been detailed, and suggestions made for the further testing of their quantitative relativities.

Actively transcribed genes are more susceptible to nuclease digestion, an observation suggested to reflect an altered state of chromatin organization. It has been hypothesized that exposure or sequestration of chromatin domains is a higher order gene regulatory mechanism. In order to test whether tissue lineage is organized by mechanisms at the level or chromatin structure, three cardiac phenotype-conferring genes (atrial natriuretic factor, myosin light chain-1-ventricular and alpha-tropomyosin) have been assessed for DNase 1 sensitivity in nuclei prepared from tissues of the developing guinea pig. These data have been related to the level of tissue mRNA expression of these genes to ascertain whether the exposed state of genes can occur when transcription is low or undetectable. Although this phenomenon was evident in some cases, the data were not consistent with mechanisms at the level of chromatin structure directing tissue type.

The activities and interactions with cellular structure of glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase have been studied in the major tissues of the guinea pig during development. The extent of activity variation in these tissues is described along with the putative physiological determinants of these alterations in activity. As to binding, overall the present data provide a firm indication that the extent of enzyme-structure interactions is appreciable at all ontogenic stages, and when viewed in conjunction with other parallel studies on other enzymes and other animals, serve to confirm the broad biological significance of enzyme-structure associations in the compartmentation of glycolysis. The existence and significance of genetic and epigenetic modifications of these enzymes during development is also discussed.

factors influence the proportion of dementia subtypes. Dementia in India is expected to reach epidemic proportions in the next two decades but studies on dementia are few. We studied patients attending a memory clinic in a private hospital in South India to describe the clinical profile and compare the socio-cultural factors influencing diagnosis and dementia care in this population with studies from developed countries. Methods: Consecutive patients attending the memory clinic at Manipal hospital, Bangalore over three years were included. Socio-demographic information including income, education and linguistic background was collected. All patients underwent detailed neurological evaluation, cognitive testing, blood tests and neuroimaging. The diagnosis of MCI, dementia and the different subtypes was based on standard criteria. Results: The mean age at presentation was 65.8(9.0) years, range 4087 years. There were 127 men and 93 women. Of the total 220 patients, MCI was diagnosed in 57 (25.9%), Alzheimer’s disease (AD) in 62 (28.1%), vascular dementia (VaD) in 38 (17.3%), and mixed dementia in four patients. 37 (16.8%) patients were diagnosed as frontotemporal lobar degeneration (FTD) and its variants. Other degenerative dementias were seen in 13 and miscellaneous causes in 8 patients. One patient did not appear to have any cognitive impairment. Majority of the patients (80.4%) were bilingual or multilingual and 10 (4.9%) patients were illiterate. VaD was more common in men (3:1) and AD in women (1.5:1). Majority of the MCI patients had depression (54.4%) and seven patients developed AD during follow-up. All the patients were cared for at home by relatives except for one patient who had an appointed caretaker. Conclusions: Alzheimer’s disease was more common than vascular dementia in this study from an urban hospital in South India, in spite of the high prevalence of vascular risk factors in this population. Depression was a common cause of mild cognitive impairment. In this study of a relatively young (mean age) dementia cohort, all patients had home based care in contrast to studies from developed countries. P1-146 PREDICTORS OF COGNITIVE DECLINE AT 18 MONTH FOLLOW UPAMONG 1112 PARTICIPANTS IN THE AUSTRALIAN IMAGING, BIOMARKERS AND LIFESTYLE FLAGSHIP STUDY OFAGEING (AIBL) Kathryn A. Ellis, Christopher Rowe, ColinMasters, Cassandra Szoeke, Kevin Taddei, Ralph Martins, Victor Villemagne, Michael Fahey, David Ames, PaulMaruff, Ping Zhang, Greg Savage, AIBLResearch Group, Lance Macaulay, University of Melbourne, Kew; Austin Health, University of Melbourne, Heidelberg, Melbourne; University of Melbourne, Melbourne, VIC; CSIRO, Melbourne; Edith Cowan University, Perth; Edith Cowan University, Perth; Austin Health, Melbourne; Division of Mathematics, Informatics and Statistics, CSIRO, Parkville, VIC; National Ageing Research Institute, Parkville; CogState, Melbourne; CSIRO, Parkville; Macquarie Centre for Cognitive Science, Macquarie University, Sydney, NSW; Mental Health Research Institute, Perth; CSIRO, Parkville.