Path analysis of psychopharmacological data: Catecholamine breakdown in man

This article applies path analysis to the problem of characterizing metabolic alterations in catecholamine systems when only static or single measures of precursor and products are available. In this article, simulated data from kinetic models of norepinephrine metabolism were examined using path analysis. The method of path analysis, which is based on correlations between compartments and not actual flow, correctly identified operative and nonoperative metabolic pathways in simulated models. In addition, actual data from normal subject as to the 24-hour urinary values for norepinephrine, normetanephrine, vanillymandelic acid, and 3-methoxy-4-hydroxyphenylglycol were analyzed using path analysis. It was found that metabolic routes that are known to be incomplete did not fit these data, whereas the known metabolic pathways for norepinephrine were correctly identified using path analysis. These results suggest that path analysis may provide a useful tool in identifying normal and abnormal catecholamine metabolic pathways in experimental situations where only single values of precursor and products are available.