This study of nearly 3000 type 2 diabetes patients, average age 62, found that those who had persistent protein in their urine over four to five years had greater declines in their brain's information-processing speed than those with no protein in their urine. The decline in patients with persistent protein in the urine was greater than 5%.
Future mental decline
The findings suggest that protein in the urine – a condition called albuminuria – may be an early warning sign of future mental decline, according to the study, which was published online on 29 August in the Clinical Journal of the American Society of Nephrology.
"Our finding was a subtle change in cognition," Dr Joshua Barzilay, of Kaiser Permanente of Georgia and the Emory School of Medicine, said in a journal news release. "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, when [mental] impairment generally becomes clinically evident."
People with diabetes are 50% to 60% more likely to suffer mental decline than those without diabetes, according to the news release.
"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," Barzilay said. "Moreover, albuminuria is also common among older people with hypertension without diabetes."
Although the study linked protein in the urine with a sign of mental decline in older adults with type 2 diabetes, it did not establish a cause-and-effect relationship.
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