Effects of escitalopram on attentional bias to cocaine-related stimuli and inhibitory control in cocaine-dependent subjects

Abstract

Key characteristics of cocaine dependence include attentional bias to cocaine cues and impaired inhibitory control. Studies suggest that serotonin modulates both cocaine cue reactivity and inhibitory control. We investigated effects of the selective serotonin reuptake inhibitor escitalopram on cocaine cue reactivity and inhibitory processes in cocaine-dependent subjects. In a double-blind placebo-controlled design, cocaine-dependent subjects received placebo (n=12) or escitalopram (n=11; 10 mg on days 1-3, 20 mg on days 4-24 and 10 mg on days 25-28) orally, once daily for 4 weeks. The cocaine Stroop and immediate memory task (IMT) were administered at baseline, days 1, 4, 11, 18 and 25 after placebo or escitalopram initiation. There were no significant between-group differences in baseline performance on the cocaine Stroop task or the IMT. On day 1 (acute phase), escitalopram produced a significantly greater decrease from baseline than placebo in attentional bias measured by cocaine Stroop task 5 hours post-dose. No significant changes from baseline in attentional bias were observed on subsequent test days (chronic phase). Inhibitory control as measured by IMT commission error rate was not significantly different between two groups in either the acute or chronic phase. Consistent with preclinical data, serotonin-modulating drugs like escitalopram may have acute effects on cocaine cue reactivity in human cocaine users.

Keywords: Escitalopram; attentional bias; cocaine Stroop task; cocaine dependence; inhibitory control.

Figure 1

Escitalopram decreased attentional bias acutely but not chronically. Attentional bias (mean ± SEM) was used to compare effects of escitalopram. The attentional bias was calculated as the difference of reaction times (cocaine-related words - non-cocaine-related words). A smaller number indicated less attentional bias to cocaine-related words. Dose of escitalopram: 10 mg daily for days 1–3, 20 mg daily for days 4–25; 10 mg daily for days 26–28. Computer tasks were performed on 4 days before first dose (baseline, session 0), day 1 (acute, session 1), days 4, 11, 28, 25(chronic, session 2–5). * p < 0.05, vs. baseline attentional bias of the escitalopram subjects. Plc: placebo; Esc: escitalopram. A. Acute effects of escitalopram; B. Chronic effects of escitalopram.