Kidney Function Can Affect Brain Function

--by Suzanne Boothby

The Gist

The first study to determine how the brain is affected by impaired renal function identified multiple cognitive changes in kidney patients. Temple University scientists found that decreased kidney function is associated with reduced global cognitive ability, abstract reasoning, and verbal memory.

Researchers discovered that the greater a person’s decrease in renal function, the greater the decrease in their overall cognitive function, especially in the areas of reasoning and memory. The study highlighted two points: the importance of diagnosing and managing chronic kidney disease and the extent of the decrease in cognitive function for kidney disease sufferers.

The Expert Take

The body's organ system is intricately linked, so the research findings are not as surprising as expected, according to the study authors.

“The brain and kidneys are both organs that are affected by the cardiovascular systems," said the study's lead author, Adam Davey, associate professor of public health at Temple's College of Health Professions and Social Work. "They are both affected by things like blood pressure and hypertension, so it is natural to expect that changes in one organ are going to be linked with changes in another."

Davey's findings are particularly relevant for people who suffer from chronic kidney disease and who may need extra support as they age.

"As we get older, our kidney function tends to decrease naturally, so if there's an extra issue involved in renal function, like chronic kidney disease, we need to know about it as soon as possible," he said. "That is something that needs to be managed, just like you would manage hypertension."

Source and Method

Researchers from Temple, the University of Maine, and the University of Maryland observed longitudinal data, five years apart, from nearly 600 people.

They wanted to determine how much subjects' kidney function had changed during that time period, and to what degree it related to changes in cognitive function. While they wanted to determine overall change, they were also looking to measure variations in specific areas of the brain, such as those that control verbal memory.

The Takeaway

This new study offers evidence that the rate of cognitive decline is associated with a deterioration in kidney function. The decrease in cognitive function was not as great as in patients with dementia or developmental delays, so it should not effect their ability to get treatment.

"Patients are still going to be able to take their medicine on time and without assistance, as well as understand the information that their physician is sharing with them about their disease," Davey said.

The research was published this week in the journal Nephrology, Dialysis and Transplantation.

Other Research

Decreased kidney function has also been linked to heart problems, including arterial stiffness, as shown in a 2005 study published in Hypertension.