Rates of age- and amyloid β-associated cortical atrophy in older adults with superior memory performance

Introduction: Superior cognitive performance in older adults may reflect underlying resistance to age-associated neurodegeneration. While elevated amyloid b (Ab) deposition (Ab1) has been associated with increased cortical atrophy, it remains unknown whether “SuperAgers” may be protected from Ab-associated neurodegeneration. Methods: Neuropsychologically defined SuperAgers (n 5 172) and cognitively normal for age (n 5 172) older adults from the Australian Imaging, Biomarkers and Lifestyle study were case matched. Rates of cortical atrophy over 8 years were examined by SuperAger classification and Ab status. Results: Of the case-matched SuperAgers and cognitively normal for age older adults, 40.7% and 40.1%, respectively, were Ab1. Rates of age- and Ab-associated atrophy did not differ between the groups on any measure. Ab2 individuals displayed the slowest rates of atrophy. Discussion: Maintenance of superior memory in late life does not reflect resistance to age- or Abassociated atrophy. However, those individuals who reached old age without cognitive impairment nor elevated Ab deposition (i.e. Ab2) displayed reduced rates of cortical atrophy

Plasma neurofilament light in behavioural variant frontotemporal dementia compared to mood and psychotic disorders

OBJECTIVE: Blood biomarkers of neuronal injury such as neurofilament light (NfL) show promise to improve diagnosis of neurodegenerative disorders and distinguish neurodegenerative from primary psychiatric disorders (PPD). This study investigated the diagnostic utility of plasma NfL to differentiate behavioural variant frontotemporal dementia (bvFTD, a neurodegenerative disorder commonly misdiagnosed initially as PPD), from PPD, and performance of large normative/reference data sets and models. METHODS: Plasma NfL was analysed in major depressive disorder (MDD, n = 42), bipolar affective disorder (BPAD, n = 121), treatment-resistant schizophrenia (TRS, n = 82), bvFTD (n = 22), and compared to the reference cohort (Control Group 2, n = 1926, using GAMLSS modelling), and age-matched controls (Control Group 1, n = 96, using general linear models). RESULTS: Large differences were seen between bvFTD (mean NfL 34.9 pg/mL) and all PPDs and controls (all < 11 pg/mL). NfL distinguished bvFTD from PPD with high accuracy, sensitivity (86%), and specificity (88%). GAMLSS models using reference Control Group 2 facilitated precision interpretation of individual levels, while performing equally to or outperforming models using local controls. Slightly higher NfL levels were found in BPAD, compared to controls and TRS. CONCLUSIONS: This study adds further evidence on the diagnostic utility of NfL to distinguish bvFTD from PPD of high clinical relevance to a bvFTD differential diagnosis, and includes the largest cohort of BPAD to date. Using large reference cohorts, GAMLSS modelling and the interactive Internet-based application we developed, may have important implications for future research and clinical translation. Studies are underway investigating utility of plasma NfL in diverse neurodegenerative and primary psychiatric conditions in real-world clinical settings

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Cognitive and brain aging and the influence of amyloid-beta

© 2019 Tri Christa K DangModels of cognitive and brain aging suggest that some cognitive decline and cortical volume loss is normal in aging beyond age 60; however, these models have failed to account for the presence of Alzheimer’s disease (AD) neuropathological markers such as amyloid-B (AB). The inadvertent inclusion of older adults who later progress from being cognitively normal (CN) to mild cognitive impairment (MCI) or dementia, or who have elevated levels of cerebral AB (AB+) may lead to inflated estimates of cognitive decline or cortical volume loss that may not be entirely due to the process of aging. The overarching aim of this thesis was to characterize the cognitive and brain morphological changes associated with normal aging, defined as the cognitive and neurobiological changes that occur with the passage of time independent of neuropathological processes. Changes in cognition and brain morphology were examined in up to 599 CN older adults from the Australian Imaging, Biomarkers and Lifestyle (AIBL) Flagship Study of Ageing who underwent repeated clinical, neuropsychological and neuroimaging (MRI and AB PET) assessments over up to 8 years. The presence of AB+ in otherwise CN older adults was associated with greater risk of future clinical disease progression to MCI or dementia, and faster rates of cognitive decline and cortical volume loss compared to those who were AB-. These results remained consistent when examined with respect to the SuperAging construct, and suggest that trajectories of cognitive and brain morphological changes in AB+ are not reflective of normal aging processes. This thesis challenges widely-accepted models of cognitive and brain aging by showing that aging is characterized by preserved cognitive function and minimal cortical volume loss, and concludes that cognitive decline is not inevitable in aging

Unhealthy habits persist:The ongoing presence of modifiable risk factors for disease in women

<div><p>Objectives</p><p>Vascular disease remains a leading cause of death. There are several vascular risk factors identified that can mitigate development of disease in ageing. We examine reported rates of modifiable risk factors in women responding to an online health questionnaire advertised by popular media.</p><p>Methods</p><p>A sample of 26 620 women aged over 18 was examined in 2015 with a cross-sectional health questionnaire. The questionnaire included self-reported health, mood, lifestyle and vascular risk factors.</p><p>Results</p><p>There remains high rates of modifiable risk factors present in women. The vast majority of women (80%) reported not eating enough fruit and vegetables. Compared to the guidelines for health, the majority did not perform enough weekly physical activity (70%) and more than half the participants were overweight (54%). Sufficient fruit, vegetables, fish, legumes and physical activity were reported in less than 30% of women!</p><p>Conclusions</p><p>Women continue to report low rates of physical activity, fruit and vegetable intake and higher BMI than recommended for good health, despite worldwide health promotion activities aimed at changing these lifestyle factors. Programs to support healthy living need to be reviewed and revised to reduce the burden of vascular disease and dementia in women. Previous guidelines are not having the important impact they should, particularly in women.</p></div