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Aotearoa New Zealand's population is ageing. Increasing life expectancy is accompanied by increases in prevalence of Alzheimer's Disease (AD) and ageing-related disorders. The multicentre Dementia Prevention Research Clinic longitudinal study aims to improve understanding of AD and dementia in Aotearoa, in order to develop interventions that delay or prevent progression to dementia. Comprising research clinics in Auckland, Christchurch and Dunedin, this multi-disciplinary study involves community participants who undergo biennial investigations informed by international protocols and best practice: clinical, neuropsychological, neuroimaging, lifestyle evaluations, APOE genotyping, blood collection and processing. A key research objective is to identify a 'biomarker signature' that predicts progression from mild cognitive impairment to AD. Candidate biomarkers include: blood proteins and microRNAs, genetic, neuroimaging and neuropsychological markers, health, cultural, lifestyle, sensory and psychosocial factors. We are examining a range of mechanisms underlying the progression of AD pathology (e.g. faulty blood–brain barrier, excess parenchymal iron, vascular dysregulation). This paper will outline key aspects of the Dementia Prevention Research Clinic's research, provide an overview of data collection, and a summary of 266 participants recruited to date. The national outreach of the clinics is a strength; the heart of the Dementia Prevention Research Clinics are its people. [ABSTRACT FROM AUTHOR]

Background: Advances in ultra‐sensitive immunoassay methods, like Single molecule array (Simoa) technology, show that Alzheimer's disease (AD) neuropathology can be detected in blood at the earliest stages of AD. This study compared cross‐sectional biomarker profiles for participants from the New Zealand‐Dementia Prevention Research Clinics (NZ‐DPRCs) who spanned the continuum from healthy older adults to a clinical diagnosis of AD. Method: Blood plasma samples were obtained from 253 NZ‐DPRC participants (aged 55 to 87) from their baseline assessment. Participants were classified as cognitively normal adults (CN, n = 34), subjective cognitive decline (SCD, n = 64), non‐amnestic mild cognitive impairment (single and multi‐domain, non‐aMCI, n = 23), amnestic MCI (single and multi‐domain, aMCI, n = 105), and AD (n = 27). Six plasma biomarkers were selected for quantification by the HD‐X Simoa analyser (Quanterix, Billerica, MA; University of Gothenburg, Sweden): AD biomarkers amyloid‐beta peptides (Aß1‐40; Aß1‐42) and phosphorylated tau species (p‐tau181; p‐tau231); neurofilament light (NfL), for general neuronal damage; and glial fibrillary acidic protein (GFAP), for astrocyte activation. Clinical, imaging and genetic demographic data were assessed in relation to the plasma biomarkers. Result: Plasma biomarkers across the five groups (figure 1) were assessed by linear regression adjusted for age and sex. P‐tau181, p‐tau231, GFAP and NfL were natural log‐transformed to approximate normality and improve homogeneity of variance. Biomarkers p‐tau181, p‐tau231, GFAP, NfL, Aß1‐42/Aß1‐40 ratio and Aß1‐42, all showed group effects (P < 0.05; Aß1‐40, p<0.08). Tukey's HSD post‐hoc test for pairwise group comparisons showed significant differences in GFAP for AD vs CN, SCD, non‐aMCI as well as SCD vs MCI (P < 0.05); p‐tau181 for AD vs CN and SCD (P < 0.05); p‐tau231 for AD vs non‐aMCI (P < 0.05); Aß1‐42 for aMCI vs CN and SCD (P < 0.05); Aß1‐42/Aß1‐40 ratio for SCD vs aMCI (P < 0.05). ROC analysis will be reported for the diagnostic accuracy of these blood analytes. Conclusion: Simoa‐quantitated blood biomarkers in the NZ‐DPRC cohort differentiates clinical groups spanning the AD continuum cross‐sectionally. [ABSTRACT FROM AUTHOR]

Background and Purpose: CB1 receptor signalling is canonically mediated through inhibitory Gαi proteins, but occurs through other G proteins under some circumstances, Gαs being the most characterized secondary pathway. Determinants of this signalling switch identified to date include Gαi blockade, CB1 /D2 receptor co-stimulation, CB1 agonist class and cell background. Hence, we examined the effects of receptor number and different ligands on CB1 receptor signalling.Experimental Approach: CB1 receptors were expressed in HEK cells at different levels, and signalling characterized for cAMP by real-time BRET biosensor -CAMYEL - and for phospho-ERK by AlphaScreen. Homogenate and whole cell radioligand binding assays were performed to characterize AM6544, a novel irreversible CB1 receptor antagonist.Key Results: In HEK cells expressing high levels of CB1 receptors, agonist treatment stimulated cAMP, a response not known to be mediated by receptor number. Δ9 -THC and BAY59-3074 increased cAMP only in high-expressing cells pretreated with pertussis toxin, and agonists demonstrated more diverse signalling profiles in the stimulatory pathway than the canonical inhibitory pathway. Pharmacological CB1 receptor knockdown and Gαi 1 supplementation restored canonical Gαi signalling to high-expressing cells. Constitutive signalling in both low- and high-expressing cells was Gαi -mediated.Conclusion and Implications: CB1 receptor coupling to opposing G proteins is determined by both receptor and G protein expression levels, which underpins a mechanism for non-canonical signalling in a fashion consistent with Gαs signalling. CB1 receptors mediate opposite consequences in endpoints such as tumour viability depending on expression levels; our results may help to explain such effects at the level of G protein coupling. [ABSTRACT FROM AUTHOR]

Background and Purpose The cannabinoid receptor type 1 ( CB1) has an allosteric binding site. The drugs ORG27569 {5-chloro-3-ethyl- N-[2-[4-(1-piperidinyl)phenyl]ethyl]-1 H-indole-2-carboxamide} and PSNCBAM-1 {1-(4-chlorophenyl)-3-[3-(6-pyrrolidin-1-ylpyridin-2-yl)phenyl]urea} have been extensively characterized with regard to their effects on signalling of the orthosteric ligand CP55,940 {(−)- cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]- trans-4-(3-hydroxypropyl)cyclohexanol}, and studies have suggested that these allosteric modulators increase binding affinity but act as non-competitive antagonists in functional assays. To gain a deeper understanding of allosteric modulation of CB1, we examined real-time signalling and trafficking responses of the receptor in the presence of allosteric modulators. Experimental Approach Studies of CB1 signalling were carried out in HEK 293 and AtT20 cells expressing haemagglutinin-tagged human and rat CB1. We measured real-time accumulation of cAMP, activation and desensitization of potassium channel-mediated cellular hyperpolarization and CB1 internalization. Key Results ORG27569 and PSNCBAM-1 produce a complex, concentration and time-dependent modulation of agonist-mediated regulation of cAMP levels, as well as an increased rate of desensitization of CB1-mediated cellular hyperpolarization and a decrease in agonist-induced receptor internalization. Conclusions and Implications Contrary to previous studies characterizing allosteric modulators at CB1, this study suggests that the mechanism of action is not non-competitive antagonism of signalling, but rather that enhanced binding results in an increased rate of receptor desensitization and reduced internalization, which results in time-dependent modulation of cAMP signalling. The observed effect of the allosteric modulators is therefore dependent on the time frame over which the signalling response occurs. This finding may have important consequences for the potential therapeutic application of these compounds. [ABSTRACT FROM AUTHOR]