paranoid condition compared to the neutral and manic condition, while bipolar patients had increased RT in the manic and depressive compared to the neutral and paranoid condition. In contrast, healthy controls had no differences in RT between word categories. Kinderman (1994) used personally descriptive adjectives with negative or positive content. He found stronger interference for positive and negative adjectives in both patient groups compared to healthy controls. Although deluded patients had significantly higher total interference scores than depressed patients, effects for word types were similar in both groups as shown by the lack of group by word interaction.
The emotional Stroop task single trial studies examined patients with chronic schizophrenia only (Demily et al., 2010; Phillips et al., 2005; Strauss et al., 2008). Phillips et al. (2005) reported interference for ne- gative and facilitation for positive words for both patients and healthy controls. Patients and healthy controls did not differ, not even in absolute reaction times and accuracy. Disorganization in patients increased the effects of emotion; stronger interference for negative and stronger faci- litation for positive words. Strauss et al. (2008) used five different word categories. In contrast to the previous study, patients showed more in- terference than healthy controls. In patients with deficit syndrome, happy words facilitate reaction times compared to healthy controls and patients without deficit syndrome. In the study of Demily et al. (2010) positive and negative words caused interference in patients and healthy controls, without a significant group by word interaction, but overall increased re- action times in patients.
An fMRI-study (I. H. Park, Park, Chun, Kim, & Kim, 2008) with an adapted Stroop-task, using pictures combined with congruent and in- congruent emotional words found no differences in reaction time (RT) between patients with schizophrenia and healthy controls for both con- gruent and incongruent trials. On fMRI-level a different pattern of BOLD- signal changes was found in the subgenual anterior cingulate gyrus, that is, a reduction during incongruent trials in healthy controls, but not in the patient group. To sum up the results of the presented studies remain inconclusive with respect to the question whether emotional modulation of selective attention differs between healthy controls and patients with schizophrenia.
To our knowledge, this study is the first study that used an emoti- onal Stroop-task in patients with recent-onset schizophrenia to examine the effect of emotion on selective attention. In contrast to the earlier mentioned studies (Bentall & Kaney, 1989; Besnier et al., 2011; Demily et al., 2010; Kinderman, 1994; Phillips et al., 2005; Strauss et al., 2008), we examined patients with short illness-duration using a Stroop-task that included emotional and colour words. By examining this patient group, effects of long-term use of antipsychotics and effects of chronicity of the disorder as cofounders are reduced, giving more insight into to what ex- tent possible impairments are already present in the early stages of the
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disorder. We hypothesized, based on the existing literature, that patients would show the same magnitude of interference in the incongruent co- lour-word condition as healthy controls and that they would show a simi- lar interference/facilitation effect of emotional words as healthy controls.
Methods
Participants
We studied 30 male patients (see table 1 for details) with recent- onset schizophrenia (defined as duration of illness < 5 years, age between 16 and 35 years) (mean age 23.9 years, SD=3.5, range=18-32). The me- dian of illness duration was 17 month (range 1-50 months). All patients were or had been hospitalized in the department of psychiatry of the Erasmus MC and were diagnosed according to DSM-IV criteria. Diagnoses were made by clinical consensus and were confirmed from case-notes using OPCRIT criteria (McGuffin, Farmer, & Harvey, 1991). Patients with symptom-duration of less than 6 months were reassessed after 6 months to comply with the DSM-IV criteria. We defined beginning of schizophre- nia as the occurrence of psychotic symptoms or clear limitations in social or occupational functioning if these occurred earlier. This method yields a relatively long duration of illness when compared with assessing only positive symptoms.
Current psychopathology was rated with the Positive and Negative Symptom Scale (PANSS) (Kay, Fiszbein, & Opler, 1987) at the day after testing. The median symptom scores were: positive 12.5 (range 7-25), negative 17 (range 8–32), general 29,5 (28-49) and total 60 (39-97). Nine patients were free of antipsychotics for at least 8 weeks and 21 (SC-med) on a stable dose of medication for at least 4 weeks (see table 1) and all patients received no additional psychotropic medication. Mean dosage expressed in chlorpromazine (CPZ)-equivalents was 347 mg (SD 149 mg). Treated and untreated patients did not differ in psychopathology ratings and age. Because the group of un-medicated patients was rather small, we analysed all patients as one group compared to healthy con- trols.
Twenty-six age- and gender-matched healthy volunteers (HC) (mean age 24.6 years, SD=4.1, range=18-31) were selected as a control group (see table 1 for details). Groups did not differ in age (t(54)=0.64, p=.56). None of the HC met criteria for a current diagnosis or history of any axis I disorder, serious somatic disorder or any cerebral trauma. Colour blindness was tested by having participants name the colour of patches that were the same colour as the stimuli used in the Stroop-task. Because of the frequent methodological problems when trying to match SC with HC on variables such as education or intelligence (Meehl, 1970), we decided not to match HC with the two patient groups on level of edu- cation. As a consequence, SC and HC differed in level of education (HC 11.96 years, SC 10.43 years, t(33.25)=10.44, p<.001). The study was approved by the research ethics committee of Erasmus MC, Rotterdam,