Kidney injury triggers brain changes: new study shows how acute kidney injury accelerates the onset of dementia, doubling the risk across various dementia types.
Study: Acute Kidney Injury and Its Association With Dementia and Specific Dementia Types: Findings From a Population-Based Study in Sweden. Image Credit: crystal light / Shutterstock.com
A recent study published in the journal Neurology examines the association between dementia risk and a prior history of acute kidney injury (AKI).
AKI and dementia
Dementia is a condition in which cognitive function declines progressively, thereby impacting the ability to perform activities of daily living (ADL). In 2019, about 55 million people were estimated to be affected by dementia.
Dementia is an incurable and progressive condition that requires active and comprehensive prevention strategies to reduce the public health burden and costs associated with its management. Several factors increase the risk of developing dementia, some of which include lower educational status, traumatic brain injury, midlife hypertension or obesity, diabetes, drinking, smoking, depression and social isolation, air pollution, and physical inactivity.
Like dementia, AKI increases the risk of adverse health outcomes, including death due to the development of heart and renal failure.
Preclinical studies indicate that AKI increases dementia risk. This association may involve multiple mechanisms, such as cerebrovascular pathology, autonomic dysfunction, abnormally low neurotransmitter levels, and neuroinflammation.
About the study
The current study involved 305,122 people 65 years and older in Stockholm, Sweden, who did not have a dementia diagnosis at baseline and had recorded kidney function measures. After a diagnosis of AKI, the study participants were monitored for any dementia.
Dementia occurrence was stratified by AKI history, the severity of AKI, AKI recurrence, and whether their kidney injury was community- or hospital-acquired.
What did the study show?
The median participant age was 75 years, 57% of whom were women. During the follow-up period of 12 years, 79,888 cases of AKI and 47,938 cases of dementia were reported.
About 36% of the study cohort was diagnosed with hypertension, whereas 11% and 10% were diagnosed with diabetes mellitus and atrial fibrillation, respectively. About 30% and 25% of the individuals were prescribed beta-blockers or angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ACEi and ARB), respectively. About 20% of the study cohort had stages three to five chronic kidney disease (CKD).
The mean age when AKI occurred was 77 years. Hypertension was the most common illness in the AKI subgroup, with a higher prevalence of 69% as compared to 36% in the entire study cohort.
The most frequently prescribed drugs reported in the AKI subgroup included ACEi, ARBs, or beta-blockers. Over 64% of individuals with AKI were also diagnosed with CKD.
Doubled risk of dementia after AKI
A total of 37 cases of dementia for every 1,000 person-years (PY) was reported among people with a history of AKI. Comparatively, before the AKI incident, the dementia incidence was 17.3 for every 1,000 PY.
After compensating for other confounding factors, the occurrence of AKI was associated with a 50% increased risk of developing any type of dementia as compared to those without a history of AKI.
An increased risk of dementia was associated with Lewy bodies (DLB)/Parkinson's disease with dementia (PDD), vascular dementia, and Alzheimer's dementia (AD) by 88%, 47%, and 31%, respectively.
Severe AKI that required hospitalization rather than outpatient management was associated with an increased dementia risk. The risk was 45% higher after AKI stage one as compared to 61% higher following stages two and three.
Hospital-acquired and hospital-managed AKI was also associated with a 55% higher dementia risk as compared to 31% for community-acquired/community-managed AKI. This risk was similarly increased at 48% and 39% for patients with two and three recurrences of AKI, respectively.
The impact of AKI on different types of dementia
The risk of DLB and PDD was 88% higher in individuals with a history of AKI as compared to an increased risk of 47% and 31% for vascular dementia and AD, respectively. In general, specific dementia types were more common with recurrent AKI and increased AKI severity.
The most common type of dementia was AD, with a total of 17,663 cases from 47,938 dementia diagnoses. Vascular dementia, DLB, PDD, and frontotemporal dementia (FTD) accounted for 29.7%, 3.6%, and 1% of dementia cases, respectively.
Age-stratified analyses identified a four-fold increased risk of DLB and PDD among those older than 85 years.
Conclusions
This study identifies individuals with AKI as a population at high risk of dementia who may benefit from close monitoring for early detection and implementation of antidementia strategies.”
The study findings confirm previous studies reporting a two-fold risk of dementia among people hospitalized with AKI while also extending these observations to a broader patient sample over a longer duration. The researchers also identified a dose-response relationship between dementia risk and AKI history, thus supporting a causal association between these two diseases.
Journal reference:
- Xu, H., Eriksdotter, M., Garcia-Ptacek, S., et al. (2024). Acute Kidney Injury and Its Association With Dementia and Specific Dementia Types: Findings From a Population-Based Study in Sweden. Neurology. doi:10.1212/WNL.0000000000209751.