A 15-year longitudinal study of Halstead-Reitan neuropsychological test performance.

Using a two-stage growth curve analysis, change over time in performance on tests in the Halstead-Reitan Battery and Average Impairment Rating (AIR) was assessed for 53 individuals who varied in age and health status. In the first stage of the analysis, estimated slope and intercept values were calculated for each individual by regressing longitudinal data points on time. In the second stage, estimated slope and intercept values obtained in the first-stage analysis were regressed on age at entry into the study with statistical control for health status, education, occupation, and gender. Control for health status had an insignificant influence on magnitude of associations between age and test performance. Age-at-entry into the study was associated with statistically significant increasing change over time (poorer performance) for tests placing relatively heavy demands on speed of psychomotor performance and for AIR.