Dementia is a major public health burden posing a devastating impact on individuals, caregivers and healthcare services. In the UK, it was estimated that around 850,000 people were living with dementia in 2015 and this number is projected to rise to over 1 million by 2025. Due to the rising ageing population and lack of medications that can cure or prevent dementia, it has become increasingly important to identify factors that can reduce the risk of dementia. Over, the last few decades, there has been growing interest on the role of infections on the risk of dementia. However, it remains unclear whether people with common infections such as pneumonia and urinary tract infections, have a higher chance of developing dementia. Additionally, common infections frequently occur in people with diabetes, and in turn diabetes is associated with dementia.
Therefore, we aim to carry out a study where we will follow individuals over time using anonymous data from primary care and hospital health records to investigate whether people with common infections are at an increased risk of developing dementia and whether this risk differs in people with and without diabetes. Infections and diabetes are potentially preventable and therefore a better understanding of how these conditions affect the risk of dementia could lead to important public health interventions. These interventions may include strategies to increase the uptake of vaccines to prevent infections, and early recognition and treatment of infections in people with diabetes to reduce the risk of developing dementia.
Dementia poses a significant burden on disability and dependence worldwide. Due to the increasing ageing population and absence of pharmacological therapies that can delay the onset or progression of dementia, dementia risk reduction has become a public health priority. Recent evidence suggests that the incidence of dementia is declining in Europe and the USA, and this change has been partly attributed to modifiable risk factors. Common infections have been identified as potential risk factors for dementia. In turn, common infections are more prevalent in diabetes, which is a strong risk factor for dementia. We hypothesise that individuals diagnosed with common infections (lower respiratory tract, urinary tract, skin and soft tissue infections and sepsis) will have an increased risk of dementia, and that this risk will increase in individuals with diabetes compared to those without diabetes.
To test this hypothesis, we will carry out a cohort study of older adults aged 65 years and over using prospectively collected CPRD data linked to hospital episode statistics. We will exclude individuals with prevalent dementia and cognitive impairment at baseline. We will assess the age-specific incidence rates of dementia in individuals with and without common infections. Then, we will use Cox regression models to investigate the effect of the type, timing and frequency of infections on the incidence of dementia, adjusting for confounding factors. We will then investigate the presence of effect modification by diabetes on the association between common infections and incident dementia. Finally, we will investigate whether there is an association between common infections and evidence of cognitive impairment. To the test the robustness of our findings, we will carry out a range of sensitivity analyses. Improved understanding of the interrelationship between infections and diabetes with incident dementia will help to inform dementia risk reduction interventions.
Primary Outcomes:
(1) Incidence of dementia (all types)
(2) Incident dementia (type-specific Alzheimers disease, vascular, mixed, other).
Secondary Outcome
(1) Evidence of cognitive impairment
Charlotte Warren-Gash - Chief Investigator - London School of Hygiene & Tropical Medicine ( LSHTM )
Rutendo Muzambi - Corresponding Applicant - London School of Hygiene & Tropical Medicine ( LSHTM )
Carol Brayne - Collaborator - University of Cambridge
Krishnan Bhaskaran - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Liam Smeeth - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Nishi Chaturvedi - Collaborator - University College London ( UCL )
HES Admitted Patient Care;Patient Level Index of Multiple Deprivation;Practice Level Index of Multiple Deprivation