The primary objective is to investigate if there is 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…
ID
Source
Brief title
Condition
- Schizophrenia and other psychotic disorders
Synonym
Research involving
Sponsors and support
Intervention
Outcome measures
Primary outcome
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 VOSP
consists of four tests assessing object perception and four tests assessing
space perception. It minimizes the involvement of other cognitive systems.
They have to do the test in writing. The IRM compromises 4 movies in which
objects dynamically appear out of random noise, mimicking suboptimal visual
situations. Subjects have to verbally name the image when recognized. The speed
and content of conscious perception will be assessed.
The primary parameter of the second part of the study is the fMRI-scan-output
while the IRM test is performed.
The primary endpoint of the retinotopic mapping fMRI-scans is cortical
activation, reflected by the Blood-Oxygen-Level-Dependent (BOLD)-level. During
this retinotopic mapping, participants are presented with a bar and wedges with
a checkerboard pattern which moves across the screen,
The primary endpoint of the resting-state fMRI-scans with pushing buttons for
VH is also cortical activation, reflected by the Blood-Oxygen-Level-Dependent
(BOLD)-level.
Secondary outcome
The secondary objective is attention. The Test Battery of Attentional
Performance (TAP) was applied for this objective. Participants have to focus
their visual attention for 10 minutes on a computer screen for this test and
have to push a button if they recognize irregularities in movement patterns. It
measures the number of omitted irregularities for sustained visual attention.
An other type of attention, working memory, is assessed by the Wechsler Adult
Intelligence Scale II Word Learning and Recalling Task. Participants are
presented with 15 words on a computer screen, then they have to try recall
those 15 words. This is repeated twice. The total correct remembered words are
measured, as are the number of wrong answers and number of words named twice
(or more times). After 20 minutes, they are asked to recall the 15 words
(delayed recall). Also, they are presented with 30 words, which include the 15
presented words as well as 15 words which were not presented. They are asked
whether they have been presented with the particular words. The number of
correct hits and correct rejections are measured.
An other secondary objective is auditory perception. .A speech discrimination
test has been applied for this objective (22).Subjects are seated in front of a
computer screen, wearing a headphone. On each trial a target word is presented
at 60-65 dB, superimposed on white background noise at 72 dB. The target words
are audible but hardly discernable. Stimuli consists of verbs and nouns. After
a 2-seconds* delay a probe stimulus, consisting of a spoken word, is presented,
free of noise, and thus clearly audible. During this phase the screen showed
only a fixation cross. The question *have you heard the word *X* in the
noise?*is then presented on the screen, with *X* referring to the probe
stimulus. Subjects indicate their answer on a five-point scale, ranging from
*certainly not* to *certainly*. The experiment consists of 50 trials. On half
of the trials, the target word and the probe word are the same.
Secondary output of the second part of the study is from the resting-state
fMRI-scans, which is the Blood-Oxygen-Level-Dependent (BOLD)-signal, which is
thought to reflect neuronal activity. Another secondary parameter is the motor
response during the visual task, as participants have to push a button when
they recognize the image, and when the central fixation square changes color.
The secondary output of the retinotopic brain mapping fMRI-scan are motor
responses, as during this test too, a central fixation square changes color
with random intervals. Participants are asked to push a button on a response
box, to keep attention constant.
The secondary output of the resting-state fMRI-scans with pushing buttons for
VH are also motor responses, as during this scan patients push a button when
they start experiencing VH, and push an other button when the VH stops.
Background summary
Schizophrenia is a psychiatric disorder, characterized by psychoses, which are
chronic or recurrent. It is a clinical diagnosis established by clinical
interviews assessing signs, symptoms and history following standardized
diagnostic criteria such as the DSM-IV. 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 69% 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, the first part of the 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.
The second part of the study consists of an object recognition task (visual
perception) during fMRI, in order to search for a bottom-up of top-down
disorder. Furthermore, connectivity between brain regions will be explored
using resting-state fMRI. An fMRI-scan including retinotopic mapping will
provide more detailed information about in particular bottom-up processing. The
fourth way to explore the neuronal base of VH in psychotic disorders is by
investigating direct neural correlates of VH, by analyzing resting-state
fMRI-data of psychotic patients while they experienced VH (only patients with
visual hallucinations will undergo this scan).
Study objective
The primary objective is to investigate if there is 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, within the framework of a recently proposed
theory on the origination of visually hallucinations (Perception and Attention
Deficit model). The objective of the second part of the study is to explore
neuronal correlates of visual hallucinations in psychosis., The objective of
the visual task is to search for changes in neuronal activity during visual
recognition reflecting a bottum-up and/or top-down disorder. The objective of
the resting-state fMRI-scans is to explore what brain mechanisms predispose
patients with a psychotic disorder to generate visual hallucinations.
The objective of the retinotopic mapping fMRI-scan is to explore detailed
differences in the visual system and in particular bottom-up processing in
psychotic patients with visual hallucinations.
The objective of the resting-state fMRI-scans with pushing buttons for VH is to
explore the direct neuronal correlates of VH in psychotic disorders.
Study design
The study is a case control study.
Study burden and risks
The first 2 visits of the study will cause very little burden because of the
durations ( 1 x 90 minutes, 1 x 120 minutes) and nature (questionnaires and
tests without invasive procedures). The second part of the study involves a
fMRI study. The first fMRI scan takes about 1 hour and 15 minutes (the total
visit takes about 2,5 hours), the check of the quality of vision 1 hour, the
second fMRI scan about 1 hour (for patients with visual hallucinations: 1 hour
and 10 minutes; the total visit takes about 2.5 hour). Patients will be
selected carefully whether they are suitable for fMRI (checking for
contra-indications like for instance a pacemaker or suffering from
claustrophobia). Participants will be well informed about the fMRI-procedure.
Pathology might show up with the fMRI. If this happens, we will inform the
general practitioner. Participants will be informed about this and have to
agree with it, otherwise they cannot be included.
This study is ethically justified, because its searches for insight in the
pathophysiology of hallucinations in schizophrenia and will cause little burden
to the patients. This study hopefully will provide more information about the
relationship between visual perception, attention and visual hallucinations in
schizophrenia, thereby possibly contributing to a better treatment in the
future.
Hanzeplein 1
Groningen 9713 GZ
NL
Hanzeplein 1
Groningen 9713 GZ
NL
Listed location countries
Age
Inclusion criteria
For patients:
1) meeting DSM-IV criteria for schizophrenia, schizophreniform disorder, schizoaffective disorder or psychotic disorder NOS;
2) in case of psychiatric comorbidity, the schizophrenia spectrum disorder is predominating;
3) age between 18-55;
4) speaking Dutch fluently;
5) 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 consent.
Exclusion criteria
1) other psychiatric disorders than above mentioned schizophrenia spectrum disorders; that presumably affect our data;
2) the presence of accompanying neurological disorders that supposedly influence our data;
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.
Exclusion criteria fMRI:
6) presence of implantable devices (electronically, magnetically or mechanically activated, for example implanted insuline pumps, cardiac pacemakers, cardioverter-defibrillators, metallic prosthetic heart valves, cochlear implants);
7) medical disorders because of which patient are unable to lie flat for about 30 minutes, for example poorly controlled heart failure and poorly controlled or severe respiratory disease;
8) ferromagnetic clips;
9) intraocular metallic bodies;
10) pregnancy;
11) claustrophobia;
12) colored tattoos;
13) coils (exception: Mirena);
14) weighing more than 140 kg.;Furthermore, healthy controls are being excluded if they ever have had a psychotic episode; or experience VH (besides due to severe sleep deprivation or use of medication/alcohol/drugs), or if they have a first degree family member who had a psychotic episode or has a psychotic disorder.
Design
Recruitment
Followed up by the following (possibly more current) registration
No registrations found.
Other (possibly less up-to-date) registrations in this register
In other registers
| Register | ID |
|---|---|
| Other | 5103 |
| CCMO | NL39518.042.12 |
| OMON | NL-OMON24629 |
| OMON | NL-OMON27034 |