Blood Sugar, Brains, and Memory
Not long ago Steven Arnold, the professor of psychiatry and neurology who serves as director of the Penn Memory Center, noted that people with diabetes have a 50 percent greater risk of developing Alzheimer’s disease than those with normal blood-sugar levels.
“It looks as though there are major abnormalities in insulin-signaling in brain cells” of Alzheimer’s patients, Arnold told the Gazette early last year [“Untangling Alzheimer’s,” Mar|Apr 2011]. “One hypothesis that we’re following up is that amyloid-beta oligomers [two or more conjoined molecules of the protein that form the plaque deposits associated with the disease] actually damage the ability of insulin to signal. Some people have referred to Alzheimer’s disease as Type 3 diabetes.”
This past March, a study by Arnold and other Penn researchers published in the Journal of Clinical Investigation confirmed that hypothesis.
“Our research clearly shows that the brain’s ability to respond to insulin, which is important for normal brain function, is going offline at some point,” says Arnold. “Insulin in the brain not only modulates glucose uptake, but also promotes the health of brain cells—their growth, survival, remodeling, and normal functioning.”
But insulin acts differently in the brain than in the rest of the body, and there is no evidence that the brains of Alzheimer’s patients are hyperglycemic (the term used to indicate high blood-sugar levels). By excluding people with a history of diabetes from the study, the researchers found that insulin resistance in the brain occurs in Alzheimer’s disease regardless of whether or not someone has diabetes.
“If we can prevent brain insulin resistance from occurring, or re-sensitize brain cells to insulin with any of the currently available insulin-sensitizing diabetes medicines,” Arnold says, “we may be able to slow down, prevent, or perhaps even improve cognitive decline.”
Three insulin-sensitizing medicines have already been approved by the FDA for treating diabetes, and since they cross the blood-brain barrier, they may have the potential to correct insulin resistance in Alzheimer’s patients and those with mild cognitive impairment (MCI). But clinical trials are still needed “to determine the impact the drugs have on Alzheimer’s disease and MCI in non-diabetic patients,” says Arnold.
—S.H.
Pain: Separate but Unequal
Low-income and minority patients are less likely than other Americans to receive guideline-recommended pain treatment, according to researchers from Penn’s School of Nursing, who found that minority patients often suffer more severe pain and physical impairments than non-minority patients. Pharmacies in their neighborhoods are also significantly less likely to have sufficient supplies of pain medications.
Chronic pain affects an estimated 116 million American adults, according to the National Academy of Sciences’ Institute of Medicine, and is the No. 1 reason that people seek medical care. It’s also costly; the annual direct and indirect costs of pain can reach $635 billion.
The researchers made a number of recommendations in the report, published in Pain Medicine, the official journal of the American Academy of Pain Medicine. Those included setting quality assurance standards for pain treatment (through the Centers for Medicare and Medicaid Services or National Quality Forum) and educating the public about pain disparities.
