A mathematical model for the analysis of cross-sectional brain glucose metabolism data in children

1. The authors present here a 5-parameter developmental function designed t o describe quantitatively the time-course of changes in glucose metabolism with age. This function consists of a plateau phase which is described by t he rate of increase with age and the height of the plateau, followed by a d ecline phase characterized by the rate of decrease to adult levels. These t wo phases are separated by a distinct point in time, at which the transitio n between the two phases occurs.. 2. The model is designed to fit published data showing that glucose metabol ic rate in frontal cortex at birth is about 60% of adult values (mean adult value is 24 mu mol/100g/min) and increases to slightly less than triple ad ult value by age 3. The metabolic rate remains at this level until the age of approximately 8 years when it starts the decline to adult values. 3. A procedure is presented which allows the approximate computation of the 98% confidence contours in data space for the developmental function. The computation is based on the joint probability function obtained from the mo del covariance matrix. 4. The newly designed 5-parameter developmental function is well suited to describe maturational changes of glucose metabolism. Due to its excellent m odel identifiability and the interpretability of individual parameters, thi s function is better suited for description of maturational changes than th e gamma-function. Furthermore, this function may provide a useful framework for interpretation of other data sets during development.