Fifteen Years of the Australian Imaging, Biomarkers and Lifestyle (AIBL) Study: Progress and Observations from 2,359 Older Adults Spanning the Spectrum from Cognitive Normality to Alzheimer's Disease

Background:

The Australian Imaging, Biomarkers and Lifestyle (AIBL) Study commenced in 2006 as a prospective study of 1,112 individuals (768 cognitively normal (CN), 133 with mild cognitive impairment (MCI), and 211 with Alzheimer’s disease dementia (AD)) as an ‘Inception cohort’ who underwent detailed ssessments every 18 months. Over the past decade, an additional 1247 subjects have been added as an ‘Enrichment cohort’ (as of 10 April 2019).

Objective:

Here we provide an overview of these Inception and Enrichment cohorts of more than 8,500 person-years of investigation.

Methods:

Participants underwent reassessment every 18 months including comprehensive cognitive testing, neuroimaging (magnetic resonance imaging, MRI; positron emission tomography, PET), biofluid biomarkers and lifestyle evaluations.

Results:

AIBL has made major contributions to the understanding of the natural history of AD, with cognitive and biological definitions of its three major stages: preclinical, prodromal and clinical. Early deployment of Aβ-amyloid and tau molecular PET imaging and the development of more sensitive and specific blood tests have facilitated the assessment of genetic and environmental factors which affect age at onset and rates of progression.

Conclusion:

This fifteen-year study provides a large database of highly characterized individuals with longitudinal cognitive, imaging and lifestyle data and biofluid collections, to aid in the development of interventions to delay onset, prevent or treat AD. Harmonization with similar large longitudinal cohort studies is underway to further these aims.

Calorie restriction attenuates LPS-induced sickness behavior and shifts hypothalamic signaling pathways to an anti-inflammatory bias

Calorie restriction (CR) has been demonstrated to alter cytokine levels; however, its potential to modify sickness behavior (fever, anorexia, cachexia) has not. The effect of CR on sickness behavior was examined in male C57BL/6J mice fed ad libitum or restricted 25% (CR25%) or restricted 50% (CR50%) in food intake for 28 days and injected with 50 μg/kg of LPS on day 29. Changes in body temperature, locomotor activity, body weight, and food intake were determined. A separate cohort of mice were fed ad libitum or CR50% for 28 days, and hypothalamic mRNA expression of inhibitory factor κB-α (IκB-α), cyclooxygenase-2 (COX-2), prostaglandin E(2) (PGE(2)), suppressor of cytokine signaling 3 (SOCS3), IL-10, neuropeptide Y (NPY), leptin, proopiomelanocortin (POMC), and corticotrophin-releasing hormone (CRH) were determined at 0, 2, and 4 h post-LPS. CR50% mice did not develop fevers, whereas the CR25% mice displayed a fever shorter in duration but with the same peak as the controls. Both CR25% and CR50% mice showed no sign of anorexia and reduced cachexia after LPS administration. Hypothalamic mRNA expression of NPY and CRH were both increased by severalfold in CR50% animals preinjection compared with controls. The CR50% mice did not demonstrate the expected rise in hypothalamic mRNA expression of COX-2, microsomal prostaglandin E synthase-1, POMC, or CRH 2 h post-LPS, and leptin expression was decreased at this time point. Increases in SOCS3, IL-10, and IκB-α expression in CR50% animals were enhanced compared with ad libitum-fed controls at 4 h post-LPS. CR results in a suppression of sickness behavior in a dose-dependent manner, which may be due to CR attenuating proinflammatory pathways and enhancing anti-inflammatory pathways.