Alzheimer's - Dementia, Author Interviews, Diabetes, JAMA, Nutrition / 31.07.2015
Insulin Resistance Linked to Poor Memory Performance
MedicalResearch.com Interview with:
Auriel A. Willette, M.S., Ph.D.
Food Science and Human Nutrition
Neuroscience Interdepartmental Graduate Program
Gerontology Interdepartmental Graduate Program
Iowa State University, Ames
Medical Research: What is the background for this study? What are the main findings?
Response: Obesity is a major health concern around the world. Obesity causes insulin resistance, defined in this case as the inability of insulin to bind to its receptor and mediate glucose metabolism. Other researchers and I have recently found that higher insulin resistance is associated with less glucose metabolism in the brains of patients with Alzheimer's disease. This relationship is found primarily in medial temporal lobe, an area necessary for generating new memories of facts and events. This is important because Alzheimer's disease is characterized by progressive decreases in glucose metabolism over time, and partly drives worse memory performance. Insulin resistance in midlife also increases the risk of developing Alzheimer's disease.
We wanted to determine if insulin resistance is linked to similar effects in cognitively normal, late middle-aged participants decades before Alzheimer's disease typically occurs. If so, insulin resistance might be an important biological marker to track from middle-age onwards. Thus, we examined the association between insulin resistance, regional glucose metabolism using FDG-PET, and memory function in 150 middle-aged participants, many of whom had a mother or father with Alzheimer's disease.
We found that higher insulin resistance was strongly associated with less glucose metabolism throughout many brain regions, predominantly in areas that are affected by Alzheimer's disease. The strongest statistical effects were found in left medial temporal lobe, which again is important for generating new memories. This relationship, in turn, predicted worse memory performance, both immediately after learning a list of words and a 20-minute delay thereafter.
The take-home message is that insulin resistance has an Alzheimer's-like association with glucose metabolism in middle-aged, cognitively normal people at risk for Alzheimer's, an association which is related to worse memory.




















