A simple urine test may be able to predict whether people with type 2 diabetes are at risk of cognitive decline, according to a study published in the Clinical Journal of the American Society of Nephrology.
Researchers from Kaiser Permanente of Georgia, Emory School of Medicine and the National Institute on Aging have discovered that a protein detectable in the urine of patients with albuminuria - a common kidney complication linked to type 2 diabetes - could be an early warning sign of cognitive decline in older diabetics.
Cognitive decline is closely associated with diabetes, say the researchers, noting that memory loss and reduced brain functioning usually occur during periods of high blood glucose (hyperglycemia) and low blood glucose (hypoglycemia).
A blood brain barrier is responsible for regulating the transport of nutrients into the brain, including glucose. The nutrients then become chemically charged particles and help brain metabolism. If the blood brain barrier receives too much or too little glucose, this can cause memory loss.
Persistent albuminuria and greater cognitive decline
For the study, the researchers recruited 2,977 diabetic patients between 2003 and 2005, with an average age of 62 years. The patients were followed-up until 2009.
They were required to undergo three neuropsychological tests. The first at the beginning of the study, the second at 20 months and the third at 40 months. The tests monitored the patients' information processing speed, verbal memory and executive function.
Results of the study showed that diabetics with persistent albuminuria over a 4- to 5-year period showed a higher percentage of decline on processing speeds compared with patients who did not have albuminuria.
Patients who had persistent and progressive albuminuria showed more than a 5% decline in scores of information processing speeds, but not with verbal memory or performance of executive function.
Dr. Joshua Barzilay of Kaiser Permanente of Georgia and Emory School of Medicine, explains:
"Our finding was a subtle change in cognition. However, were this decline to continue over 10 to 15 years it could translate into noticeable cognitive decline by the age of 75 to 80 years, when cognitive impairment generally becomes clinically evident."
"Given how common albuminuria and diabetes are in the older population, these findings have a great deal of importance from a population point of view. Moreover, albuminuria is also common among older people with hypertension without diabetes."
However, the study authors note that this research does not rule out the possibility that other processes may have caused cognitive decline in the patients.