The Island Study Linking Ageing and Neurodegenerative Disease (ISLAND): a Prospective, Online, Public Health Cohort Study Targeting Dementia Risk Reduction (Preprint)

BACKGROUND Up to 40% of incident dementia is considered attributable to behavioural and lifestyle factors. Given the current lack of medical treatments and the projected increase in dementia prevalence, a focus on prevention through risk reduction is needed. OBJECTIVE The Island Study Linking Ageing and Neurodegenerative Disease (ISLAND) is a long-term prospective, online cohort study with nested interventions. This 10-year public health project aims to increase dementia risk knowledge and promote changes in dementia risk behaviours at individual and population level. METHODS ISLAND participants (target n=10,000) reside in Tasmania, Australia and are aged 50 years or over. Survey data on knowledge, attitudes and behaviours related to modifiable dementia risk factors will be modelled longitudinally with intervention engagement indices, cognitive functioning and blood-based biomarkers. RESULTS In the initial 12 months, 6,410 participants provided baseline data and have been provided with a personalised dementia risk profile, and guidelines for reducing risk, across nine behavioural and lifestyle domains. Within this first year over one quarter of the cohort (27%) undertook the Preventing Dementia massive open online course and 12% enrolled in university study via the Campus intervention. CONCLUSIONS Recruitment targets are feasible and efforts are ongoing to achieve a representative sample. Findings will inform future public health dementia risk reduction initiatives, by showing whether, when and how dementia risk can be lowered through interventions delivered in an uncontrolled, real-world context.