Dr. Gail Musen is an Assistant Investigator in the Section on Clinical, Behavioral, and Outcomes Research at Joslin, and an Assistant Professor in Psychiatry at Harvard Medical School. Dr. Musen is a cognitive psychologist investigating the effects of diabetes on the brain. Her research investigates both type 1 and type 2 diabetes.
Dr. Musen's research has focused on changes in brain structure and function as a result of diabetes. She uses a variety of MRI techniques and neuropsychological assessments. She and her colleagues have reported that patients with type 1 diabetes showed subtle changes in brain structure, in particular, gray matter density, that were associated with higher frequency of severe hypoglycemic episodes and poorer glycemic control. These changes are very small and do not imply that patients will show clinically significant cognitive impairment. However, brain regions involved in memory, attention and language processing were among those that showed reduced gray matter density in patients and it is not clear whether these brain changes will have a more profound effect as the patient ages.
Dr. Musen has also used another type of MRI, functional MRI (fMRI) to study brain function both type 1 and type 2 diabetes. Specifically, she has used this technique to investigate the brain's response while subjects are exposed to hypoglycemia, are asked to carry out specific cognitive tasks or are simply instructed to lie quietly in the scanner. fMRI measures the brain "in action" and detects the level of deoxyhemoglobin in the brain. Activated regions are those that are working the hardest during that time period.
Through the use of fMRI scanning during hypoglycemia, Dr. Musen hopes to better understand which brain regions respond to hypoglycemia and how metabolic abnormalities affect brain regions responsible for glucose sensing and cognition. Diabetic patients experience dips and peaks in blood glucose levels that are much more dramatic than in people without diabetes. As a result, the central nervous system may adapt to this situation and as a result the warning signals that alert patients to treat a low blood sugar are delayed, often until it is too late for them to think clearly. This condition is referred to as hypoglycemia unawareness. Dr. Musen hopes to use this research as a stepping stone to understand the mechanisms responsible for hypoglycemia unawareness.
Dr. Musen's recent research is also focusing on evaluating people with insulin resistance and type 2 diabetes to determine whether they may be at increased risk for Alzheimer's Disease. A number of studies in other groups of people at risk for Alzheimer's Disease have demonstrated that functional brain imaging techniques can identify abnormalities in brain metabolism that may serve as an early biomarker for Alzheimer's disease. Reduced brain activity in a variety of brain regions (e.g., the posterior cingulate and temporoparietal posterior association cortical regions) are evident not only in patients with Mild Cognitive Impairment who may later progress to Alzheimer's Disease, but also in young people who carry the ApoEε4 gene, long before cognitive impairment is evident. Dr. Musen's lab is investigating the question of whether this same brain pattern is evident in people with insulin resistance. In people who show this pattern of brain activation, the hope is that early detection can help medical professionals identify the problem early and implement treatments that may work best when the disease is still in its prodromal form. Thus, this research could have strong public health implications.
Through the combination of structural and functional brain imaging and cognitive testing, Dr. Musen hopes to identify the relationships between the effects of diabetes on the integrity of the central nervous system.