Prenatal stimulant exposure affects alerting and executive control in six and seven-year-olds

Abstract

Attentional processes were investigated in 53 six and seven-year-olds, representing three populations: (1) Follow-ups at a clinic for children who tested positively for cocaine/amphetamine exposure at birth (PSE group; n = 13); (2) children diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD), with no known history of prenatal stimulant exposure (ADHD group; n = 23); and (3) randomly selected age and demographically matched controls (n = 17). The Continuous Performance Test (CPT) was used to assess two components of attention, the "alerting" system (AS) and the "executive" system (ES). The AS was operationally defined as the ability to sustain reaction speed over blocks of trials, while ES was defined as the ability to inhibit responses to non target stimuli. PSE children had significantly slower hit reaction times than either controls or ADHD children, while ADHD children were slower than controls only for the longest (4-sec) interstimulus interval (ISI) condition. Other reaction time contrasts showed no significant differences between the PSE and ADHD groups. In comparison to controls, both the PSE and ADHD groups showed more variability in reaction times, which increased over time on task, espe cially in the 2- and 4-sec ISI conditions. Both the PSE and ADHD groups committed significantly more impulsive errors than controls but the errors of the ADHD group were associated with time on task and ISI, while errors for the PSE tended to occur more randomly. In summary, PSE children are very much like ADHD children in terms of overall performance configuration, but their behavior deficits tend to be somewhat more pronounced and less predictable from variations in test conditions.