The present study investigated the attentional bias induced by drug-related stimuli in active abusers; abstinent abusers on opioid substitution therapy; and abstinent drug-dependent patients in recovery on a community-based non-pharmacological therapy programme. Drug-dependent groups included both cocaine and heroin abusers.

Classical and emotional Stroop tasks were used to test all drug-dependent patients and controls with no history of addiction. Response times were recorded. An interference effect was obtained by comparing the congruent and incongruent conditions in the classical Stroop version. An attentional bias towards drug cues was derived by comparing latencies in the neutral and emotional conditions of the emotional Stroop.

No between-group differences were found in the classical Stroop. In the emotional Stroop, active drug-dependent patients showed higher attentional bias (i.e. longer response times to drug-related words) than any of the other three groups.

The attentional bias induced by drug cues in patients with addiction disorder might change depending on the patients' clinical status. All treated patients, whether on opioid substitution therapy or on community therapy, showed less attentional bias towards drug-related stimuli than active drug users, although the observed smaller bias was most likely induced by therapy acting through different mechanisms. Although drug-cues response is influenced by other multiple variables, e.g. motivation, craving, classical conditioning and substance availability, these data lend support to the hypothesis that treatment might contribute to decrease the attentional bias towards drug cues, which seems to play a critical role in achieving a positive outcome in the treatment of addiction.

Smoking is highly prevalent in people diagnosed with schizophrenia, but the reason for this co-morbidity is currently unclear. One possible explanation is that a common abnormality underpins the development of psychosis and independently enhances the incentive motivational properties of drugs and their associated cues. This study aimed to investigate whether incentive salience attribution towards smoking cues, as assessed by attentional bias, is heightened in schizophrenia and associated with delusions and hallucinations.

Twenty-two smokers diagnosed with schizophrenia and 23 control smokers were assessed for smoking-related attentional bias using a modified Stroop task. Craving, nicotine dependence, smoking behaviour and positive and negative symptoms of schizophrenia were also recorded.

Both groups showed similar craving scores and smoking behaviour according to self-report and expired carbon monoxide (CO), although the patient group had higher nicotine dependence scores. Attentional bias, as evidenced by significant interference from smoking-related words on the modified Stroop task, was similar in both groups and correlated with CO levels. Attentional bias was positively related to severity of delusions but not hallucinations or other symptoms in the schizophrenia group.

This study supports the hypothesis that the development of delusions and the incentive motivational aspects of smoking may share a common biological substrate. These findings may offer some explanation for the elevated rates of smoking and other drug use in people with psychotic illness.