Improving Visual Attention in Schizophrenia

Study Overview
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Brief Summary
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This study investigates whether visual attention can be improved in individuals with schizophrenia by stimulating the brain via transcranial Direct Current Stimulation (tDCS).

Detailed Description
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Individuals with schizophrenia tend to display abnormal visual attention when performing visual tasks, typically spending less time on salient features of the stimuli (e.g. core facial features or body movement in social tasks), and instead focusing on idiosyncratic features of an image or video. Poor visual attention in schizophrenia has been directly linked to poorer social cognitive performance (e.g. recognizing emotional expressions or social cues) which can impact an individual's day to day functioning. Transcranial Direct Current Stimulation (tDCS) is a form of noninvasive neurostimulation which has been proposed as a therapeutic procedure in numerous psychiatric disorders. TDCS in schizophrenia has been demonstrated to improve a wide range of cognitive processes, and in healthy adults, tDCS has been demonstrated to improve aspects of social cognition. TDCS thus appears to be a promising therapeutic technique that may be useful for improving visual attention in patients with schizophrenia, and potentially impact social cognitive performance via an underlying mechanism tying the two. This study will compare visual performance in individuals with schizophrenia across two conditions: active anodal tDCS and sham tDCS, while also comparing between brain stimulation sites: rTPJ and dmPFC.

Official Title
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Improving Visual Attention to Social Stimuli in Individuals With Schizophrenia

Conditions
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Schizophrenia, Schizoaffective Disorder

Intervention / Treatment
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* Device: Active anodal tDCS
* Device: Sham tDCS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: DSM-IV-TR or DSM-5 diagnosis of schizophrenia or schizoaffective disorder and clinically stable (i.e. no hospitalizations) for at least 8 weeks prior to informed consent and be on a stable medication regimen for at least 6 weeks with no dose changes for a minimum of 2 weeks prior to informed consent. Exclusion Criteria: The presence or history of a pervasive developmental disorder or mental retardation as defined by a premorbid IQ < 70 Presence or history of medical or neurological disorders in which neural stimulation would be contraindicated (e.g. presence of epilepsy or history of seizures) Presence of sensory limitations, including visual or hearing impairments that interfere with assessment History of electroconvulsive therapy Not proficient in English Presence of substance abuse in the past one month or dependence not in remission in the past six months

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Participants will be paired based on key demographic criteria and assigned to one of two stimulation locations (rTPJ or dmPFC), participants will then complete active and sham stimulation sessions in a randomized, counterbalanced order approximately one week apart.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Anodal followed by sham stimulation tDCS to rTPJ<br>cross-over design - active stimulation tDCS to the rTPJ followed by behavioral testing. After 1 week washout, sham stimulation tDCS to the rTPJ followed by behavioral testing. | Device: Active anodal tDCS<br>* active anodal tDCS with behavioral tasks to assess visual attention<br>Device: Sham tDCS<br>* sham tDCS with behavioral tasks to assess visual attention<br>|
| Active Comparator: Anodal followed by sham stimulation tDCS to dmPFC<br>cross-over design - active stimulation tDCS to the dmPFC followed by behavioral testing. After 1 week washout, sham stimulation tDCS to the dmPFC followed by behavioral testing. | Device: Active anodal tDCS<br>* active anodal tDCS with behavioral tasks to assess visual attention<br>Device: Sham tDCS<br>* sham tDCS with behavioral tasks to assess visual attention<br>|
| Experimental: Sham followed by anodal stimulation tDCS to rTPJ<br>cross-over design - sham stimulation tDCS to the rTPJ followed by behavioral testing. After 1 week delay, active stimulation tDCS to the rTPJ followed by behavioral testing. | Device: Active anodal tDCS<br>* active anodal tDCS with behavioral tasks to assess visual attention<br>Device: Sham tDCS<br>* sham tDCS with behavioral tasks to assess visual attention<br>|
| Active Comparator: Sham followed by anodal stimulation tDCS to dmPFC<br>cross-over design - sham stimulation tDCS to the dmPFC followed by behavioral testing. After 1 week delay, active stimulation tDCS to the dmPFC followed by behavioral testing. | Device: Active anodal tDCS<br>* active anodal tDCS with behavioral tasks to assess visual attention<br>Device: Sham tDCS<br>* sham tDCS with behavioral tasks to assess visual attention<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Visual Attention to Static Faces | Visual attention measured via eye-tracking (percentage of time attending to investigator designated AOIs) when viewing static, emotional faces (stimuli: Emotion Recognition - 40). AOIs for static faces will be defined as core facial features (i.e. eyes, nose, mouth). | Assessment will be completed 30 minutes after completion of the active/sham stimulation | 
| Visual Attention to Dynamic Actor | Visual attention measured via eye-tracking(percentage of time attending to investigator designated AOIs) when viewing videos of a single actor (stimuli: Bell Lysaker Emotion Recognition Task). AOIs for this task will be defined as core facial features (i.e. eyes, nose, and mouth). | Assessment will be completed 30 minutes after completion of the active/sham stimulation | 
| Visual Attention to Dynamic Social Scenes | Visual attention measured via eye-tracking (percentage of time attending to investigator designated AOIs) when viewing videos of two or more actors in a scene (stimuli: The Awareness of Social Inference Task Part 3, Version A). AOIs for this task will be defined as salient social and contextual stimuli (e.g. social stimuli are faces of actors, while contextually salient stimuli include items actors are talking about, such as a plate full of food or an empty wallet). | Assessment will be completed 30 minutes after completion of the active/sham stimulation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Fixation Stabilization | Stabilization of visual fixation on fixation circle positioned in middle of screen. Participants will be placed in front of an eyetracking device and asked to keep their eyes focused on a circle in the middle of the screen. Stabilization will be measured via eye-tracking as the deviation from a single point on screen, calculated by assessing the sum of squares of both the x and y axis (output from eyetracking device). Higher number indicates more movement, and thus less stabilization. | Assessment will be completed 30 minutes after completion of the active/sham stimulation |