Differential measures of 'sustained attention' in children with attention-deficit/hyperactivity or tic disorders: relations to monoamine metabolism

Controversy exists on whether the constructs rested by paper/pencil and com puterized continuous-performance tests (CPT) are similar, and the deficits recorded in children with attention-deficit/hyperactivity symptoms (ADHD) a re comparable. Signal-detection measures were recorded on four such tests o f 'sustained attention', with increasing working-memory requirements in hea lthy children (14; mean 10 years), and those with ADHD (14; mean 10 years) or a tic syndrome (TS, 11; mean 11 years). Clinical associations were sough t. from 24-h urinary measures of monoamine activity. The cancellation paper /pencil test revealed no group differences for errors or signal detection m easures. On the CPT, ADHD children made more omission and commission errors than control subjects, but TS children made mostly omissions. This reflect ed the poor perceptual sensitivity (d-prime, d') for ADHD and conservative response criteria (beta) for TS children. This group difference extended to the CPTax, which was shown on a regression analysis to test for putative w orking-memory-related abilities as well as concentration. In all children, immediate response-feedback reduced omissions, and modestly improved d'. CP Tax performance related negatively to dopamine metabolism in control subjec ts and to serotonin metabolism in the ADHD group. But comparisons between t he metabolites in the ADHD group suggest that increased serotonin and decre ased noradrenaline, with respect to dopamine metabolism, may detract from C PT performance in terms of d'. CPT tasks demonstrated a perceptual-based im pairment in ADHD and response conservatism in TS patients independent of di fficulty. Catecholamine activity was implicated in the promotion of percept ual processing in normal and ADHD children, but serotonin activity may cont ribute to poor CPTax (working-memory) performance in ADHD patients. (C) 200 0 Elsevier Science Ireland Ltd. All rights reserved.