Dementia, a syndrome that leads to deterioration in cognitive function mainly in older people, is currently the seventh leading cause of death and affects more than 55 million people globally. Since only about one-fifth of the disability-adjusted life years associated with dementia can be attributed to known modifiable risk factors, further work is needed to find and mitigate other modifiable risk factors causally associated with the future risk of dementia. Obstructive sleep apnoea syndrome (OSAS) is a common clinical condition in which the throat narrows or collapses repeatedly during sleep, causing obstructive sleep apnoea events. It has been recognised as an independent risk factor for a number of chronic conditions. Emerging evidence suggests that OSAS may be associated with an increased risk of dementia, a general term for the impaired ability to remember, think, or make decisions that interferes with doing everyday activities. However, studies looking specifically at links between OSAS and the incidence of dementia are scarce, have poor study designs, and with small sample sizes. There is a need for large-scale population-based studies to investigate associations between OSAS and the risk of dementia and whether effective management of OSAS mitigates this risk. We hypothesise that OSAS is an independent risk factor the for future development of dementia. The objective of this study is to investigate the association between OSAS and the incidence of dementia.
Aims:
To investigate whether the presence of obstructive sleep apnoea syndrome (OSAS) is associated with an increased or decreased risk of subsequent development of dementia.
Methods:
Using routinely collected primary care-based data across the UK (2000 - 2022), adults with OSAS will be compared with matched individuals without OSAS for the risk of developing dementia in later life. Competing risk Cox proportional hazard regression models will be used to calculate crude hazard ratios (crude HRs) and adjusted hazard ratios (adjusted HRs), together with their corresponding 95% CIs. Death during the follow-up period will be treated as a competing event.
Outcomes:
The primary outcome is all-cause dementia. The secondary outcomes are the two main subtypes of dementia, Alzheimer’s disease and vascular dementia.
Exposures:
The presence of OSAS.
Participants:
Adults aged 18 years and above with no prior diagnosis of dementia at baseline and registered between 1st of January 2000 and to 31st of December 2022. Individuals with Parkinson’s disease at baseline will be excluded. All participants must have been registered with the general practice for at least one year before the index date (start of follow-up).
Covariates:
Sociodemographic characteristics, behavioural risk factors, comorbidities, biomarkers, and medications will be adjusted to account for residual confounding.
The primary outcome is all-cause dementia. The secondary outcomes are the two main subtypes of dementia, Alzheimer’s disease and vascular dementia.
Shamil Haroon - Chief Investigator - University of Birmingham
Jingya Wang - Corresponding Applicant - University of Birmingham
Anuradhaa Subramanian - Collaborator - University of Birmingham
Neil Cockburn - Collaborator - University of Birmingham
Patient Level Index of Multiple Deprivation;Practice Level Index of Multiple Deprivation