Measuring kidney function may help predict dementia risk in patients with hypertension
In a study of patients with hypertension, declining kidney function was associated with risk for incident dementia and cognitive impairment.
“[Chronic kidney disease] CKD and dementia are common conditions among older adults and frequently co-occur, suggesting they share a common pathogenesis,” Manjula Kurella Tamura, MD, MPH, of the Palo Alto VA Health Care System and Stanford University School of Medicine, and colleagues, wrote. “Hypertension is a potentially modifiable risk factor for CKD and dementia, affecting more than half of all adults over 60 years of age.”
According to the researchers, previous work has explored intensive vs. standard blood pressure targets for patients with CKD, with several studies showing intensive treatments increase the risk for eGFR decline and incident CKD. However, they wrote, these studies did not consider potential effects on cognitive function.
Furthermore, while there have been observational studies in patients on dialysis demonstrating an association between lower BP and poorer cognition, limited data exist regarding the relationship between BP targets and cognitive function in those with earlier CKD stages.
To investigate, Kurella Tamura and colleagues administered cognitive assessments to 8,563 participants in the Systolic Blood Pressure Intervention Trial (28.2% had eGFR < 60 mL/min per 1.73m2 at baseline). All participants were required to complete at least one assessment during a median follow-up of 5.1 years.
Throughout follow-up, probable dementia occurred in 3.8% of participants; mild cognitive impairment (MCI) occurred in 7.6% of participants.
Researchers found that while participants with a baseline eGFR of less than 60 mL/min/m2 were not more likely to develop either condition, an eGFR decline of at least 30% was associated with a higher risk for probable dementia.
In addition, it was determined that an incident eGFR of less than 60 mL/min per 1.73m2 was associated with a higher risk for MCI and a composite of dementia or MCI.
Regarding the intensity of hypertensive treatment, the researchers wrote that, “although these kidney events occurred more frequently in the intensive treatment group, there was no evidence that they modified or attenuated the effect of intensive treatment on dementia and MCI incidence.”
They also noted that that neither baseline nor incident urinary albumin-to-creatinine ratio (UACR) of less than 30 mg/g was not associated with incidence of probable dementia or MCI. In addition, UACR did not appear to modify the effect of intensive treatment on either outcome.
The researchers concluded: “These findings are consistent with the hypothesis that declining kidney function and declining cognitive function share a common pathogenesis independent of BP control, and imply that large declines in kidney function may identify a population at higher risk for adverse cognitive outcomes.”