Antioxidants may prevent cognitive impairment in diabetes

Long-term decline in cognitive function, with everyday learning and memory tasks becoming harder and taking longer to complete, is a common consequence for patients who frequently experience low blood sugar levels when using insulin to manage their diabetes. Previous studies in mice have shown that reoccurring episodes of low blood sugar leads an accumulation of cell damaging free radicals in the brain. Whether this build-up of free radical stress directly effects cognitive function, and if the body's own antioxidative systems, which can remove free radicals, can be harnessed to counteract these changes and improve quality of life is not known.

In this study, Dr Alison McNeilly and colleagues at the University of Dundee used insulin to induce repeated bouts of low blood sugar in a mouse model of type-1 diabetes. In the experiment, one group of mice were also dosed with the vegetable derived antioxidant sulforaphane (SFN). Mice treated with SFN showed increased expression of antioxidant markers, decreased free radical cell damage and had significantly improved cognitive ability in memory tasks.

Dr McNeilly commented, "Low blood sugar is an almost unavoidable consequence of insulin therapy. This work demonstrates that by improving the body's own antioxidant defence system we can reverse some of the side effects associated with diabetes, such as poor cognitive function."

Dr McNeilly and her colleagues now intend to find out if boosting the body's antioxidative system can minimise cognitive decline associated with low blood sugar in humans, by using drugs based on the chemical structure of SFN.

Dr McNeilly said, "The concentration of SFN used in this study would not be attainable in a normal diet rich in vegetables. However, there are numerous highly potent compounds in clinical trials which may prevent cognitive impairments caused by free radicals to help diabetes patients."