Diabetes and Cognitive Decline: New Study Reveals Link

Link between diabetes and cognitive decline
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The connection between having diabetes and developing cognitive decline has been studied before, and now a new study sheds more light on the subject. Results of the nine-year study show a strong risk of cognitive decline among people who develop type 2 diabetes later in life, highlighting the need for individuals of all ages to take steps to prevent the disease.

What is the diabetes and brain connection?

There are plenty of reasons for wanting to prevent the development of type 2 diabetes. In addition to having an impact on everyday dietary choices and often requiring the use of daily medication, it is also associated with significant complications, including eye disease (diabetic retinopathy), nerve damage (neuropathy), kidney failure, amputation, and an increased risk of heart attack and stroke.

Now add cognitive decline to the list. Researchers at the University of California, San Francisco (UCSF) and the San Francisco VA Medical Center evaluated 3,069 adults older than 70 who participated in the Health, Aging, and Body Composition (Health ABC) Study. Here is what the authors found:

  • At the start of the study, 717 participants (23.4%) had diabetes and 2,352 (76.6%) did not
  • 159 (5.2%) participants developed the disease over the nine-year period
  • During the study, people with diabetes had significantly worse cognitive decline than individuals without diabetes
  • Individuals who had diabetes at the start of the study experienced a more rapid cognitive decline than people who developed diabetes during the study
  • Among individuals with diabetes at the start of the study, higher hemoglobin A1c levels (greater than 7%) were associated with worse cognitive scores than those with lower levels. Hemoglobin A1c is a measure of the percentage of glycated hemoglobin in the blood over the past 2 to 3 months and is an important indicator of blood glucose control

This study is the first to show that the greater risk of cognitive decline associated with having diabetes is not only seen in people who develop the disease earlier in life but later in life as well. It also is the first time researchers linked the risk of cognitive decline to the severity of diabetes.

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Diabetes today and tomorrow
The Centers for Disease Control and Prevention estimates the number of people with diagnosed diabetes will increase from 11 million to 20 million by the year 2050 (these numbers don't include the millions who are undiagnosed), while the World Diabetes Foundation estimates 438 million people around the world will have the disease by 2030. Given this epidemic, the need for effective preventive strategies and better disease management is critical.

Diabetes prevention and management involves lifestyle choices: not smoking, achieving and maintaining a healthy weight, eating a nutritious diet (e.g., Mediterranean diet), and exercising regularly--steps that can help control weight, blood glucose levels, and a healthy sensitivity to insulin.

Importance of the diabetes study
This study highlights the relationship between diabetes and poor blood glucose control and worsening of cognitive functioning. According to Kristine Yaffe, MD, the study's lead author and chief of Geriatric Psychiatry and Director of the Memory Disorders Clinic at the San Francisco VA Medical Center, their findings are "another piece of the puzzle in terms of linking diabetes to accelerated cognitive aging."

To help fill in the pieces of this puzzle, Yaffe believes future research should investigate whether steps to prevent, delay, or better control diabetes might also reduce an individuals' risk of developing cognitive decline later in life.

SOURCES:
Centers for Disease Control and Prevention
World Diabetes Foundation
Yaffe K et al. Diabetes, glucose control, and 9-year cognitive decline among older adults without dementia. Archives of Neurology 2012 Jun 18

Image: Morguefile

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