Table 1.

Characteristics of studies for opioid use disorders.

Study	Study design	Sample size	Types of sample	Demographics of sample	Country	Diagnosis of sample	Method of diagnosis	Attention bias method	Outcomes
OPIOID USE DISORDERS
Franken et al. (15)	Randomised trial	21 heroin dependent participants 30 control participants	Participants with heroin dependence were recruited from an inpatient treatment center Participants in the control group were recruited among clinical and administrative staff in the clinic	71.4% males (heroin dependent) 83.3% (control group) Mean age 31.5 years (heroin dependent) Mean age 34.8 (control group) Mean self-reported duration of heroin dependence was 93.9 months	Netherlands	Heroin Dependence	Based on the DSM-IV criteria for heroin dependence	Drug Stroop task	Higher overall reaction time for heroin participants as compared to control participants Mean pre-experimental craving was 13.8, mean post masked Stroop was 7.19 and mean post unmasked Stroop was 15.2
Lubman et al. (16)	Randomised trial	16 methadone maintained opiate addicts 16 age-matched control	Heroin addicts were recruited from local drug services Staff from these services were recruited as controls	Opiate group: mean age 31.4, Male to Female 11:5 Control group: mean age 31.7, male to female 8:8	United Kingdom	Heroin Dependence	ICD-10 and DSM IV	Pictorial Probe Detection Task	Faster reaction times to probes that replaced drug stimuli, indicative of the presence of an attentional bias
Marissen et al. (17)	Randomised trial	110 Participants assigned to either cue exposure therapy or placebo psychotherapy	Abstinent heroin addicts who were admitted voluntarily to an in-patient drug-free therapeutic center in the Hague	89% males, mean age 34 years old Average age of onset of heroin usage was 21.4 years, most have used heroin for 9.3 years	Netherlands	Heroin Dependence	DSM-IV criteria for heroin dependence	Emotional Stroop Task	Pre-treatment attentional bias predicted relapse at 3 months follow-up Reduction of attentional biases in both experimental conditions
Bearre et al. (18)	Cross-sectional study	60 participants	Recruited from a harm reduction program (methadone maintenance or needle exchange)	44 participants on methadone maintenance, 16 on needle exchange program Mean age 32 years, mean 7.07 months of heroin use	United Kingdom	Heroin dependence	Not mentioned	Flicker change blindness paradigm	Attention bias increase as the monthly frequency of heroin use increases
Fadardi et al. (19)	Cross-sectional study	53 drug abusers with 71 non-abusers as controls	Drug abusers were recruited from a local drug-use services clinic and were on methadone maintenance therapy Controls were students, academic staff and other personnel of Ferdowsi University of Mashhad and people from the local community who were visiting the university	Drug abusers: 100% male, mean age was 36.57 years Control: 54% male, mean age 26.62 years	Iran	Opiate abuse	Not mentioned	Persian Version of classic and addiction Stroop tests	Higher attentional bias for drug-related stimuli than non-abusers
Waters et al. (20)	Longitudinal study	68 heroin dependent inpatients	Addiction treatment center	85.3% Males Mean age 40.87 Age of first heroin use was 22.34 Total years of heroin use was 14.13	Netherlands	Heroin Dependence	DSM-IV criteria for heroin dependence	Drug Stroop task	Attentional biases to drug cues were elevated during temptation episodes
Zhou et al. (21)	Cross-sectional study	22 male abstinent heroin abusers 20 healthy males	Recruited from a legal rehabilitation center in Yunnan Province, China	All males Mean age 31.45	China	Opioid dependence	DSM-IV criteria for heroin dependence	Pull/Push task (Based on Approach/Avoidance Task rationale)	Abstinent individuals had higher tendencies to approach heroin-related stimuli, and avoidance tendencies toward heroin stimuli were reduced
Anderson et al. (22)	Cross-sectional study	17 opioid dependent patients 17 controls	Opioid dependent patients were from local methadone clinic Controls recruited from newspaper advertisements and flyer postings	Patients: mean age 44.4; male to female 9:8 Control: mean age 42.9; male to female 9:8	United States	Opioid Dependence	Structured clinical interview for DSM-IV (SCID-I)	Attentional Visual Search Task	Patients in treatment for addiction experience greater difficulty ignoring stimuli associated with non-drug reward.
Charles et al. (23)	Cross-sectional study	23 opioid dependent 21 healthy controls	Those prescribed with opioid substitution within the National Health Service	Mean age for Patient group (ABM-away) 43.91, (ABM-control) 45.17 Control group (ABM-away) 41.00, ABM-Control 38 Gender M:F for patient group ABM-away 10:1, ABM-control 10:2 Control group ABM-away 8:3, ABM-contor 7:3	United Kingdom	Opioid Dependence	Not mentioned	Visual Probe Tasks	No baseline differences in attentional biases between control and patient group No change in AB following bias modification Treatment adherent patients who did not use illicit opiates on top of their prescribed opiates had statistically significantly greater attention bias away from substance-related stimuli
Ziaee et al. (24)	Cross-sectional	24 in experimental group received Drug Attention Control Training Program in addition to treatment as usual 24 in control group received only treatment as usual	Participants were drug abusers who were undergoing methadone maintenance therapy in a drug-abuse clinic	Mean age of experimental group was 33.17; mean age of control group was 38.75 The drugs that participants most commonly abused were opium, crystal and opium sap	Iran	Drug abuse and on methadone maintenance therapy	Not mentioned	Drug Stroop test	Experimental group showed reduction in attention bias for drug related stimuli, temptations to sue, doses of medicine, and number of relapses; increases on the Readiness to Change Questionnaire and 2 subscales of the Situational Confidence Questionnaire
Zhao et al. (25)	Cross-sectional	30 heroin dependents 39 healthy controls	Heroin dependents were from a methadone clinic Controls were service workers and security guards from a university	In heroin group: mean age 39.83, male to female 2:1 In control group: mean age 41.42, male to female 9:10	China	Heroin dependence	DSM-IV	Visual probe task with concurrent eye movement monitoring	Heroin group reacted faster to probes associated with substance-related pictures than neutral pictures, and they directed more initial fixations and maintained longer initial fixation durations toward substance-related pictures than neutral pictures.