The effect of alteration of glucose use on brain function

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Glucose has long been accepted as the mandatory fuel for the brain although it is not fully understood why this is so. Impairment of the glucose supply to the brain results in impairment in brain functions, coma and ultimately death. As a result the body possesses rigid regulatory systems to maintain blood glucose levels within set limits. In certain conditions where blood glucose levels frequently drop below normal, the brain compensates by increasing the uptake of glucose into the brain thus keeping the glucose supply normal despite lower than normal blood glucose concentrations. In these conditions, which include diabetic hypoglycaemia unawareness, anorexia and starvation, the normal hormonal systems warning of low blood glucose are bypassed. However, despite normal glucose supply to the brain, the performance of the brain is still adversely affected. The electrical activity of the brain changes, reaction times slow, and vigilance is decreased. This implies that, despite the brain having a normal supply of glucose, the glucose is being used differently and that these differences affect the functional performance of the brain. The AIMS of this study are to determine: 1. How does the use of glucose vary in the hypoglycaemia unawareness state? 2. How do these variations effect the performance of the brain? The SIGNIFICANCE of this work lies in 1. Increasing our understanding of the role of glucose in the brain, 2. Increasing our understanding of how the brain works, and, 3. Increasing our understanding of why cognitive impairment occurs in disorders such as diabetes, anorexia and starvation and whether this impairment is reversible. 4. Developing application of a relatively new technique, functional magnetic resonance spectroscopy, for use study of biochemical and cognitive brain disorders.