This Physician’s Weekly feature on managing cognitive decline in older adults with diabetes was completed in cooperation with the experts at the American Diabetes Association.
More than 25% of Americans aged 65 and older has diabetes, and the aging of the overall population has been identified as a significant driver of the diabetes epidemic. “Diabetes in older adults is associated with higher mortality, reduced cognitive and functional status, and increased risk of institutionalization,” explains Hermes Florez, MD, PhD, MPH. “Importantly, diabetes has been linked to significantly higher risks of cognitive impairment, a greater rate of cognitive decline, and increased risk of dementia.”
While various complications of diabetes are well known and well researched, the effect diabetes has on the brain has historically received relatively little attention. “The risk of both diabetes and cognitive impairment increases with age,” Dr. Florez says. “The presentation of cognitive impairment in people with diabetes can vary, ranging from subtle executive dysfunction to overt dementia and memory loss. We’re starting to see links between diabetes and dementia and Alzheimer’s disease, but researchers are still conducting analyses to further increase our knowledge on these associations.”
Consensus Report on Diabetes in Older Adults
In the December 2012 issue of Diabetes Care, the American Diabetes Association released a consensus report on diabetes and older adults. Dr. Florez, who was on the writing group that developed the report, says that an important component to managing older adults with diabetes is the role of cognitive impairment. “For older patients with diabetes, treatments will need to be simplified whenever possible, and caregivers should be involved during consultations. The presence of cognitive impairment can make it challenging for clinicians to help their patients reach individualized targets for A1C, blood pressure, and cholesterol.”
The consensus report from the American Diabetes Association provides several broad recommendations for clinicians who manage older adults with diabetes (Table 1). According to recent long-term research, the presence of diabetes has been shown to significantly increase the age and sex-adjusted incidence of all-cause dementia, Alzheimer’s disease, and vascular dementia when compared with rates in people with normal glucose tolerance. “The effects of hyperglycemia and insulin on the brain are areas of intense research interest,” Dr. Florez says. “There is still much more to learn about these associations.”
Despite encouraging associations found in observational studies, randomized clinical trials of specific interventions—including cholinesterase inhibitors and glutamatergic antagonists—have not definitively established positive therapeutic benefit in maintaining or improving cognitive function, or preventing cognitive decline. Recent pilot studies in patients with mild cognitive impairment evaluating the potential benefits of intranasal insulin therapy or metformin therapy provide insights for future clinical trials and mechanistic studies.
The Impact of Diabetes Severity
In a study published in the September 2012 Archives of Neurology, researchers found that scores on cognition tests decreased among well-functioning older adults with diabetes and poor glucose control (Table 2). The findings suggest that diabetes severity may further accelerate cognitive decline. The authors noted that delaying or preventing the onset of diabetes may help maintain cognitive function in older adults, especially considering that longer duration of diabetes worsens cognitive function.
Studies examining the effect of intensive glycemic control and blood pressure control to a specific target have not conclusively shown that these strategies can consistently help prevent declines in brain function. However, Dr. Florez notes that people with diabetes are at an increased risk for health issues that may impair cognitive performance. “There are several other mechanisms that may underlie the association of diabetes, glucose control, and reduced cognitive function,” he says. “To optimize care, clinicians should strive to keep A1C, blood pressure, and lipid levels at goal so that risks for complications can be minimized.”
Screening Matters in Older Adults with Diabetes
The consensus report from the American Diabetes Association recommends that older adults with diabetes be carefully screened and monitored for cognitive impairment. Studies, however, suggest that many older adults with diabetes have unidentified cognitive deficits. “Periodic screening for cognitive dysfunction in older adults with diabetes has the potential to improve outcomes,” says Dr. Florez. Several organizations have released simple assessment tools for clinicians.
Dr. Florez adds that clinicians should not underestimate the impact that cognitive impairment can have on older adults with diabetes. “This dysfunction makes it difficult for patients to perform complex self-care tasks, such as glucose monitoring and adjusting insulin doses. It also hinders their ability to appropriately maintain the timing and content of diet. When clinicians are managing these types of patients, it’s critical to simplify drug regimens and get caregivers involved in all aspects of care. We also need to be vigilant about preventing hypoglycemia and carefully assess and reassess patients’ risk for worsening of glycemic control and functional decline.”
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