Locally produced brain insulin in memory and Alzheimer’s disease: A multi-disciplinary approach to a key question

Dr. James Johnson is one of five BC researchers leading teams supported through the British Columbia Alzheimer’s Research Award. Established in 2013 by the Michael Smith Foundation for Health Research (MSFHR), Genome British Columbia (Genome BC), The Pacific Alzheimer Research Foundation (PARF) and Brain Canada, the goal of the $7.5 million fund is to discover the causes of and seek innovative treatments for Alzheimer’s disease and related dementias.

Alzheimer’s disease (AD) – the most common form of dementia – is a fatal, progressive and degenerative disease that destroys brain cells, causing thinking ability and memory to deteriorate.

One percent of AD is the early-onset type that runs in families. While extensive studies of these forms of the disease have revealed the genes that cause them, the most common, late-onset forms of AD are understudied and poorly understood at the level required for therapeutic intervention.

Studies have shown links between Alzheimer’s disease and obesity, altered fat metabolism, insulin and diabetes, with diabetes increasing the risk of suffering from AD by 30-65 percent. Scientists have also found the brain produces a small amount of insulin with reduced levels in the brains of AD sufferers. While the function of brain insulin is a mystery, evidence suggests reduced brain insulin could play a role in Alzheimer’s disease.

Dr. James Johnson, a professor in the Departments of Cellular and Physiological Sciences and Surgery at the University of British Columbia (UBC), further found in preliminary studies that high-fat diets reduced brain insulin production. The goal of Johnson’s continuing research is to answer the key question: is the loss of brain insulin alone enough to cause cognitive impairment? Johnson will test the hypothesis that brain-produced insulin is a critical factor for the survival and function of brain cells in the context of both a genetic change that increases Alzheimer’s risk and a diet that increases Alzheimer’s risk. Using mice models lacking brain insulin, Johnson’s team will assess their ability to learn and study how their brains are reprogrammed. Insulin will be correlated with Alzheimer’s-like changes in human brains.

Information on the role and mechanisms of brain insulin through Johnson’s pioneering research has the potential to advance understanding of AD and contribute to an eventual cure. Identifying the link between diet, insulin and Alzheimer’s disease could also enable earlier diagnosis and inform strategies for Alzheimer’s prevention. Furthermore, the findings may shed light on much-needed new drug targets for Alzheimer’s disease or possibly re-purposing existing diabetes drugs.