The Australian Research Council Longevity Intervention (ARCLI) study protocol (ANZCTR12611000487910) addendum: Neuroimaging and gut microbiota protocol 11 Medical and Health Sciences 1103 Clinical Sciences 11 Medical and Health Sciences 1109 Neurosciences
Creators: name: Simpson, Tamara
name: Deleuil, Saurenne
name: Echeverria, Nicole
name: Komanduri, Mrudhula
name: Macpherson, Helen
name: Suo, Chao
name: Gondalia, Shakuntla
name: Fard, Masoumeh Tangestani
name: Pipingas, Andrew
name: Scholey, Andrew
name: Stough, Con
Publisher: name: Swinburne
Year: 2024
Subjects: classificationCode: 520201
subject: Behavioural genetics
classificationCode: 520202
subject: Behavioural neuroscience
classificationCode: 520203
subject: Cognitive neuroscience
classificationCode: 520205
subject: Psychopharmacology
classificationCode: 520206
subject: Psychophysiology
classificationCode: 520207
subject: Social and affective neuroscience
classificationCode: 520301
subject: Clinical neuropsychology
classificationCode: 520401
subject: Cognition
classificationCode: 520403
subject: Learning, motivation and emotion

description: Background: The Australian Research Council Longevity Intervention (ARCLI) was designed to investigate the effects of two active supplements, Pycnogenol and Bacopa monnieri (CDRI08) on cognitive performance in a cohort of elderly participants. An additional antioxidant supplement has been included into the trial. A neuroimaging component has also been added to the ARCLI study to investigate the neurochemical biomarkers of oxidative stress in vivo, as well as structural and functional changes associated with ageing and oxidative stress. Faecal biomarkers of gut microflora will also be analysed to investigate if gut microbiota are associated with domains of cognition (e.g., attention, processing speed, memory), mood or other ARCLI outcome variables. The aim of this paper is to update the published methods of the ARCLI clinical trial before it is completed, and data analysis commences. Methods: ARCLI is a randomised, placebo controlled, double-blind, now 4-arm clinical trial including neuroimaging and gut microflora sub-studies. Along with the demographic, haematological, mood, cardiovascular and cognitive assessments described in the initial protocol, 80 eligible participants from the overall study pool of ~ 400 will be recruited into the neuroimaging study and undergo scans at baseline, 3 months and 12 months. Proton magnetic resonance spectroscopy, resting state functional connectivity and arterial spin labelled perfusion sequences are neuroimaging techniques included for each MRI visit in the study. Similarly, approximately 300 participants from the main study pool will be recruited to provide faecal samples at baseline, 3 months and 12 months so that the gut microbiome can be studied. Discussion: ARCLI is 12-month intervention study, currently underway with a group of older adults, investigating a range of outcomes and their association with ageing. The additional measurements in the ARCLI trial will further the understanding of the underlying mechanisms associated with healthy ageing and may provide insights into novel preventative therapeutic strategies for maintaining cognitive and brain health into old age. Trial registration: Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12611000487970.