Depression, an overlooked complication of diabetes

The American Diabetes Association estimates that in the United States are about 26 million people suffering from diabetes and 79 million people that have prediabetes. There is increasingly more evidence that highlight that the brain of patients with diabetes is at risk as much as any other organ in the body.

Gail Musen, an  HMS assistant professor of psychiatry and assistant investigator in the Section on Clinical, Behavioral and Outcomes Research at Joslin Diabetes Center, said that unlike other certain diseases, the researchers did not know where to look in the brain to see the effects of diabetes. She added that they know how much diabetes can affect other organs, this is why they want to see what is the effect on the brain.

The first study led by Musen 10 years ago brought to the attention of the scientific community a better understanding of the mechanisms by which diabetes, especially type 1 diabetes, affects the brain. In 2006, Musen conducted a study published in the journal Diabetes, which highlighted that the gray matter density changes due to diabetes type 1. Results showed that both high levels of blood glucose (hyperglycemia) and low blood glucose levels (hypoglycemia) affect the brain. Although gray matter reductions are small and not necessarily led to cognitive dysfunction, though the brain regions involved are those related to memory, attention and language.

Now recent studies conducted by Musen and her colleagues showed that patients with long-standing type 1 diabetes have certain brain changes: it seems that the integrity of white matter and cortical thickness are affected. Musen said she is not sure whether these changes will have a greater impact with age. Even though, in terms of cognitive function, patients with diabetes have normal performance, their brain activity may differ from that of people without diabetes. According to Musen, such changes may precede cognitive dysfunction such as memory loss or mild cognitive impairment, a condition that may lead to Alzheimer disease.

Neurophysiologist Vera Novak, an HMS associate professor of medicine and a neurophysiologist at Beth Israel Deaconess Medical Center, led another study that revealed a mechanism by which type 2 diabetes leads to depression, memory loss and other cognitive disorders. It seems that the brain tissue is damaged by a chronic inflammatory process involving two molecules : sVCAM and sICAM: “It appears that chronic hyperglycemia and insulin resistance”the hallmarks of diabetes” trigger the release of these adhesion molecules and set off a cascade of events leading to the development of chronic inflammation,” pointed out Novak.