HEALTH NEWS

Study Title:

Diabetes Worsens Cognitive Function

Study Abstract

OBJECTIVE—Diabetes is associated with cognitive decline and dementia. However, the relationship between the degree of hyperglycemia and cognitive status remains unclear. This was explored using baseline cognitive measures collected in the ongoing Memory in Diabetes (MIND) substudy of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial.

RESEARCH DESIGN AND METHODS—The relationship of A1C and fasting plasma glucose (FPG) levels to performance on four cognitive tests was assessed, adjusting for age and other determinants of cognitive status. The tests were the Digit Symbol Substitution Test (DSST), Mini Mental Status Examination (MMSE), Rey Auditory Verbal Learning Test, and Stroop Test.

RESULTS—A statistically significant age-adjusted association was observed between the A1C level and the score on all four cognitive tests. Specifically, a 1% higher A1C value was associated with a significant 1.75-point lower DSST score (95% CI –1.22 to –2.28; P < 0.0001), a 0.20-point lower MMSE score (–0.11 to –0.28; P < 0.0001), a 0.11-point lower memory score (–0.02 to –0.19, P = 0.0142), and a worse score (i.e., 0.75 s more) on the Stroop Test (1.31–0.19, P = 0.0094). The association between the DSST score and A1C persisted in all multiple linear regression models. FPG was not associated with test performance.

CONCLUSIONS—Higher A1C levels are associated with lower cognitive function in individuals with diabetes. The effect of glucose lowering on cognitive function will be determined by the ongoing ACCORD-MIND trial.

From press release:

Blindness, renal failure, stroke and heart disease are potential complications of type 2 diabetes, which currently afflicts more than 15 million Americans. Now research from Tel Aviv University has found more worrying news ― type 2 diabetes can be a risk factor accelerating cognitive decline and dementia.

Dr. Tali Cukierman-Yaffe, a physician and researcher from TAU’s Sackler School of Medicine, found that people with diabetes were 1.5 more likely to experience cognitive decline, and 1.6 more likely to suffer from dementia than people without diabetes. Her recent publication in the journal Diabetes Care suggests that higher-than-average levels of blood glucose (blood sugar) may have a role in this relationship.

Her work is part of the ongoing Memory in Diabetes (MIND) project, a sub-study of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial.

First Step Towards New Treatments

“Our results send an important message to the public,” says Dr. Cukierman-Yaffe. “We have shown conclusively that there is a relationship between diabetes and cognitive dysfunction. This should be known by diabetics and their doctors. Knowledge is the first step towards action.

“Intact thinking is essential for managing the disease,” Dr. Cukierman-Yaffe adds.

Clinicians today work with the patient to prevent complications of diabetes. Early detection of visual problems, for example, can be treated with laser surgery if diagnosed early enough, and blindness can be avoided in some cases.

“Today, diabetes cannot be cured. We can however delay or prevent many of its complications,” says Dr. Cukierman-Yaffe. “Diagnosing cognitive dysfunction at a pre-clinical stage is the first step in finding new treatment options."

A New Association with Poor Cognitive Performance

Dr. Cukierman-Yaffe’s work opens a new opportunity for researchers to better understand the cognitive risks associated with diabetes and dysglycemia. She points out that diabetes, unlike other chronic disease states, is a complex disease to manage and one that requires intact cognition in the patient. As the mind starts deteriorating, so does the patient’s ability to treat the diabetes effectively. Disease management can then spiral out of control.

Findings in her recent study show that in people with type 2 diabetes, higher levels of haemoglobin A1C (a measure of average blood glucose) are significantly associated with poorer performance on three cognitive tasks which require memory, speed and ability to manage multiple tasks at the same time. A higher A1C level was also associated with a lower score on a test of global cognitive function.

The results of the study suggest that lowering A1C levels could slow the accelerated rate of cognitive decline experienced by people with diabetes. However prospective studies and clinical trials are needed in order to prove this. The ongoing ACCORD-MIND study, in which study patients are followed over time and are tested three times during the trial will test the hypothesis that lowering A1C could result in improved cognitive function.

Study Information

Tali Cukierman-Yaffe, Hertzel C. Gerstein, Jeff D. Williamson, Ronald M. Lazar, Laura Lovato, Michael E. Miller, Laura H. Coker, Anne Murray, Mark D. Sullivan, Santica M. Marcovina, Lenore J. Launer
Relationship Between Baseline Glycemic Control and Cognitive Function in Individuals With Type 2 Diabetes and Other Cardiovascular Risk Factors: The Action to Control Cardiovascular Risk in Diabetes-Memory in Diabetes (ACCORD-MIND) trial
Diabetes Care
2009 February
Action to Control Cardiovascular Risk in Diabetes-Memory in Diabetes (ACCORD-MIND) Investigators. Tel Aviv University.