AKI Increases Long-Term Dementia Risk

Patients who’ve recovered from acute kidney injury (AKI) have a 3-fold higher risk of developing dementia than hospitalized patients who avoid AKI, according to a study presented at Kidney Week 2018.

Patients who experience AKI may face long-term health complications even if they completely recover. Previous studies have shown that experiencing AKI increases the risk of developing chronic kidney disease (CKD) and cardiovascular disease. But the long-term consequences of AKI for brain health weren’t clear.

“We used to think that almost all cases of AKI would have complete recovery, but now realize that many people have later development of CKD,” said Hamid Rabb, MD, medical director of the Johns Hopkins Kidney Transplant Program in Baltimore. “Clinicians should be aware that AKI could have important kidney as well as non-kidney distant organ long-term effects, and therefore follow patients closely even after seeming resolution of AKI.”

To assess the potential long-term effects on the brain, Jessica Kendrick, MD, associate professor at the University of Colorado School of Medicine, and her colleagues looked at 2082 patients without a history of dementia treated in an integrated health system in Utah between 1999 and 2009. During the study, which followed patients for a median of 5.8 years, 97 patients developed dementia. Those who had AKI were more likely to develop dementia than those who didn’t (7.0% vs 2.3%). The hazard ratio was 3.4 (95% CI 2.14–5.40). The magnitude of the dementia risk was comparable to the risks of other long-term complications, noted Kendrick.

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The study was “provocative” and needs to be confirmed by others, Rabb said. He noted it is not surprising that AKI might lead to an increased risk of dementia.

“AKI is well known to cause clinical changes in brain acutely, and some of these could lead to chronic changes,” Rabb said.

Exactly how AKI might contribute to an increased risk of dementia is not clear. Kendrick noted it may be related to endothelial dysfunction after AKI. Now, she and her colleagues are looking at whether AKI may change cerebrovascular dynamics.

Rabb noted that patients with AKI may have other risk factors for dementia, such as diabetes, vascular disease, older age, or hypertension. Additionally, AKI is known to cause dysfunction in distant organs. Rabb suggested it might affect the blood-brain barrier, microglial activation, or protein leakage in the brain, which might contribute to dementia as well. He said it would be interesting to look at the renal function in patients who developed dementia compared with those who didn’t, because it is possible they did not completely recover kidney function after AKI.

Kendrick noted it is also not clear how AKI contributes to other long-term complications like CKD or cardiovascular disease.

“It’s an area that really needs to be investigated,” she said.

Kendrick said it is important to research whether changes in the way hospitals care for patients with AKI could help prevent long-term complications, for example, whether more monitoring of kidney function after AKI would help identify patients’ persistently elevated proteinuria.

“Even when people do well and recover, it’s still associated with significant adverse outcomes,” she said. “It would be nice to have something to offer them to hopefully prevent these complications from developing.”

“Acute Kidney Injury is Associated with an Increased Risk of Dementia” (Abstract 3024328).

December 2018 (Vol. 10, Number 12)