Children with Kidney Disease Show Blood Flow Changes in Brain

Blood flow changes in the brains of children, adolescents and young adults with chronic kidney disease may explain why many face a higher risk of cognitive impairment, according to a study in Radiology.

Prior research has linked chronic kidney disease with subcortical ischemic lesions, atrophy and deficits in cognitive performance. While chronic kidney disease in adults is frequently associated with age-related disorders such as hypertension and diabetes, the disease in childhood often occurs congenitally, yet still affects brain development and cognitive function.

“It’s not clear if the brain problems from kidney disease seen in adults are secondary to the hypertension produced by the disease,” said coauthor John A. Detre, MD, professor of neurology and radiology, director of the Center for Functional Neuroimaging in Radiology and vice chair for research in neurology at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia. “In our study, we wanted to look at patients with early kidney disease, before they’ve experienced decades of high blood pressure. In doing this, we could separate the kidney disease effects from those of chronic high blood pressure.”

Dr. Detre and colleagues assessed blood flow in the brains of 73 pediatric kidney disease patients under 16 years old and 57 similarly aged control participants using arterial spin labeling MRI.

Patients with kidney disease showed higher cerebral blood flow compared with controls in certain brain regions – a surprising finding, considering that decreased cognitive performance is generally associated with decreased blood flow in the brain, such as in aging and dementia.

There are possible reasons for this unusual phenomenon, Dr. Detre said. “It may indicate compensatory hyperactivity, in which the brain regions are working extra hard to maintain performance,” he said. “Another possibility is that there’s a disturbance in the regulation of blood flow in these patients.”

Study Offers Clues on Brain Physiology

White matter cerebral blood flow and blood pressure were also correlated, suggesting that kidney disease patients have problems with cerebrovascular autoregulation, a dysfunction that could potentially lead to white matter injury, according to Dr. Detre.

“Chronic kidney disease appears to affect brain physiology and function even early in the disease,” he said. “This study gives us clues about what changes in brain physiology might underlie cognitive changes.”

Among those changes were differences in blood flow between patients and controls in areas of the brain that correlated with cognitive problems. Compared with controls, kidney disease patients had cerebral blood flow differences in the default-mode network. Patients with low executive function had significant differences in cerebral blood flow compared with controls.

The findings point to cerebral blood flow measurements with arterial spin labeling as a potentially valuable tool in characterizing cerebrovascular function in chronic kidney disease.

“This technique provides a noninvasive way of quantifying cerebral blood flow that doesn’t require use of contrast agent, which is contraindicated in patients with kidney dysfunction,” Dr. Detre said.