Improving Visual Attention in Schizophrenia

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

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.

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.

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.

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.

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.

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.

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).

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).

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).

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.

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