Kidney injury causes changes in the brain: New research shows how acute kidney injury accelerates the onset of dementia, doubling the risk in several types of dementia.
Study: Acute kidney injury and its association with dementia and specific types of dementia: findings from a population-based study in Sweden. Image credits: crystallight / Shutterstock.com
A recent study published in the journal Neurology examines the association between dementia risk and a history of acute kidney injury (AKI).
AKI and dementia
Dementia is a condition in which cognitive function gradually declines, affecting the ability to perform activities of daily living (ADL). In 2019, it was estimated that approximately 55 million people suffered from 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 treatment. Several factors increase the risk of developing dementia, including lower educational status, traumatic brain injury, hypertension or obesity in middle age, 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 kidney failure.
Preclinical studies indicate that AKI increases the risk of dementia. 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 aged 65 years and older in Stockholm, Sweden, who had no dementia diagnosis at baseline and had recorded renal function measurements. After a diagnosis of AKI, the study participants were monitored for possible dementia.
The occurrence of dementia was stratified by history of AKI, severity of AKI, recurrence of AKI, and whether the kidney injury was acquired in the community or in the hospital.
What did the research show?
The average age of participants was 75 years, of whom 57% were women. During the 12-year follow-up period, 79,888 cases of AKI and 47,938 cases of dementia were reported.
Approximately 36% of the study cohort was diagnosed with hypertension, while 11% and 10% were diagnosed with diabetes mellitus and atrial fibrillation, respectively. Approximately 30% and 25% of subjects were prescribed beta-blockers or angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ACEi and ARB), respectively. Approximately 20% of the study cohort had stage three to five chronic kidney disease (CKD).
The average age at which AKI occurred was 77 years. Hypertension was the most common disease in the AKI subgroup, with a higher prevalence of 69% compared to 36% in the entire study cohort.
The most commonly prescribed drugs reported in the AKI subgroup included ACEi, ARBs, or beta blockers. More than 64% of individuals with AKI were also diagnosed with CKD.
Doubled risk of dementia after AKI
A total of 37 cases of dementia per 1,000 person-years (PY) were reported among people with a history of AKI. In comparison, before the AKI incident, the incidence of dementia was 17.3 per 1,000 PY.
After compensating for other confounding factors, the occurrence of AKI was associated with a 50% increased risk of developing any form of dementia in people with no 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 disease (AD) at 88%, 47% and 31% respectively.
Severe AKI requiring hospitalization rather than outpatient treatment was associated with an increased risk of dementia. The risk was 45% higher after AKI phase one, compared to 61% higher after phases two and three.
Community-acquired and community-managed AKI was also associated with a 55% increased risk of dementia, compared with 31% for community-acquired/community-managed AKI. This risk was similarly increased by 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, compared to an increased risk of 47% and 31% for vascular dementia and AD, respectively. Overall, specific forms of dementia were more common with recurrent AKI and increased severity of AKI.
The most common form of dementia was AD, with a total of 17,663 cases out of 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 analyzes identified a fourfold increased risk of DLB and PDD among individuals older than 85 years.
Conclusions
This study identifies individuals with AKI as a population at high risk for dementia who may benefit from close monitoring for early detection and implementation of antidementia strategies..”
The study results confirm previous studies reporting a two-fold risk of dementia in people hospitalized with AKI, while also extending these observations to a broader patient group over a longer period of time. The researchers also identified a dose-response relationship between dementia risk and history of AKI, supporting a causal link between these two diseases.
Magazine reference:
- Xu, H., Eriksdotter, M., Garcia-Ptacek, S., et al. (2024). Acute kidney injury and its association with dementia and specific types of dementia: findings from a population-based study in Sweden. Neurology. doi:10.1212/WNL.0000000000209751.