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Onderzoek naar ‘dingen zien die er niet zijn’ bij psychotische aandoeningen


- candidate number21812
- NTR NumberNTR5103
- ISRCTNISRCTN no longer applicable
- Date ISRCTN created
- date ISRCTN requested
- Date Registered NTR18-mrt-2015
- Secondary IDsNL39518.042.12 
- Public TitleOnderzoek naar ‘dingen zien die er niet zijn’ bij psychotische aandoeningen
- Scientific TitleThe relationship between visual hallucinations, visual perception and attention in patients with schizophrenia
- ACRONYMINZICHT
- hypothesisOur hypothesis is that patients with a psychotic disorder with visual hallucinations perform worse on neuropsychological tests measuring attention and visual perception compared to schizophrenic patients and healthy controls
- Healt Condition(s) or Problem(s) studiedHallucinations, Psychosis
- Inclusion criteriaPatients must fulfill the following criteria: 1) meeting DSM-IV criteria for schizophrenia, schizophreniform disorder or schizoaffective disorder; 2) age between 18-55; 3) speaking Dutch fluently; 4) being able to give informed consent. Healthy controls must fulfill the following criteria:
1) age between 18-55;
2) speaking Dutch fluently;
3) being able to give informed consentí.
- Exclusion criteriaExclusion criteria are:
1) other psychiatric disorders than schizophrenia;
2) the presence of accompanying neurological disorders;
3) visually acuity less than 50 percent (Snellen chart);
4) visually field defects (Donders technique);
5) cognitive impairment, which is assessed by Mini-Mental State Examination. The cut-off point is <26.


Furthermore, healthy controls are excluded if they ever have had a psychotic episode; if they have visual hallucinations; or if they have a first degree family member who had a psychotic episode or a psychotic disorder.
- mec approval receivedyes
- multicenter trialno
- randomisedno
- group[default]
- Type2 or more arms, non-randomized
- Studytypeobservational
- planned startdate 16-apr-2013
- planned closingdate
- Target number of participants51
- Interventions
- Primary outcomeThe primary endpoint is visual perception, assessed by The Visual object and Space Perception Battery (VOSP), which comprises four tests designed to assess object perception and four tests for space perception.
Visual perception is also assessed by the Image Recognition Movies task (IRM). This test compromises 4 movies in which objects dynamically appear out of random noise, mimicking suboptimal visual situations.
- Secondary outcomeThe secondary objective is attention. The subtest ‘Vigilance’ of the Test battery of Attentional Performance (TAP) (21) was applied for this objective. An other type of attention (working memory) is also assessed by the Wechsler Adult Intelligence Scale (WAIS) III Word Learning and Recalling Task.
An other secondary objective is auditory perception. A speech discrimination test has been applied for this objective.
- Timepoints
- Trial web site
- statusopen: patient inclusion
- CONTACT FOR PUBLIC QUERIES Marouska van Ommen
- CONTACT for SCIENTIFIC QUERIES Marouska van Ommen
- Sponsor/Initiator University Medical Center Groningen (UMCG)
- Funding
(Source(s) of Monetary or Material Support)
University Medical Center Groningen (UMCG)
- Publications
- Brief summarySummary:
Rationale: schizophrenia is a psychiatric disorder, characterized by psychoses, which are chronic or recurrent. Hallucinations in schizophrenia are typically considered to be auditory, consisting of ‘hearing voices’, although hallucinations in other sensory domains also exist. Visual hallucinations are present among 14% to 72% of the patients. A challenging explanation for the occurrence of recurrent complex visual hallucinations (RCVH) in schizophrenia is offered by the Perception and Attention Deficit (PAD) model, which states that they only occur in the presence of a dual deficit in attention and perceptional processes. Several studies show that in schizophrenia there are combined deficits in attention and perception. However, until now no attempts have been made to establish direct evidence for this relationship by comparing visual hallucinating schizophrenic patients with non-visual hallucinating patients and healthy controls. Therefore, this study consists of four neuropsychological tests assessing attention and visual perception. A fifth test assessing auditory perception is included as well, because we would like to investigate whether a possible change in perception is modality-dependent or not.
Objective: The primary objective is to investigate whether there’s a difference in the performance on tasks measuring visual perception and attention between visual hallucinating schizophrenic patients, schizophrenic patients who do not hallucinate and healthy controls.
Study population: this study involves visual hallucinating schizophrenic patients (age between 18 and 55 years), as well as matched non-visual hallucinating schizophrenic patients and healthy controls. They are matched based on age, gender and on their cognitive profile.
Main study parameters: the primary parameter of the first party of the study is object and space perception, assessed by the Visual Object and Space Perception (VOSP) battery. Object perception is also assessed by Image Recognition Movies (IRM).
The secondary objective is attention. The subtest ‘Optical Vigilance’ of the Test Battery of Attentional Performance (TAP) will be applied for this objective. The WAIS Word Learning (and Recalling) Task is also included to assess attention ((working) memory). Patients are presented 15 words, they are asked to remember them and recall them immediately, and after 20 minutes.
An other secondary objective is auditory perception. This is assessed by a speech discrimination task.
Nature and extent of the burden and risks associated with participation, benefit and group relatedness: this study will cause very little burden because of the short durations (1 x 1.5 hours, 1 x 2 hours) and nature (questionnaires and tests without invasive procedures). It is not expected that participants will benefit from taking part in this study. However, this study hopefully will provide insight about the relationship between visual perception, attention and visual hallucinations in schizophrenia, thereby possibly contributing to a better treatment in the future. Subjects will be compensated for their travelling-expenses (0.19 euro/km by car, or economy class if they travel by train or bus tickets). In addition, they will be given a small incentive (25 euro VVV coupon)

Country of recruitment: the Netherlands
- Main changes (audit trail)
- RECORD18-mrt-2015 - 25-apr-2015


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