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 to describe quantitatively the time-course of changes in glucose metabolism with age. This function consists of a plateau phase which is described by the rate of increase with age and the height of the plateau, followed by a decline phase characterized by the rate of decrease to adult levels. These two phases are separated by a distinct point in time, at which the transition between the two phases occurs. 2. The model is designed to fit published data showing that glucose metabolic rate in frontal cortex at birth is about 60% of adult values (mean adult value is 24 mumol/100 g/min) and increases to slightly less than triple adult 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 model covariance matrix. 4. The newly designed 5-parameter developmental function is well suited to describe maturational changes of glucose metabolism. Due to its excellent model identifiability and the interpretability of individual parameters, this function is better suited for description of maturational changes than the gamma-function. Furthermore, this function may provide a useful framework for interpretation of other data sets during development.