Neural Markers of Treatment Mechanisms and Prediction of Treatment Outcomes in Social Anxiety

The primary aim of this study is to discover neural mechanisms (via EEG and MRI) associated with variation in response to CBT and/or combined CBT and SSRI interventions. The goal is to develop a rigorous model that predicts individual differences in response to treatments using baseline neural markers. The investigators will recruit 190 adults with social anxiety disorder (SAD) and 50 adult controls. All adults with SAD will participate in group CBT for SAD. Non-responders will continue on with individual CBT plus the addition of sertraline for another 12 weeks. 50 controls will receive baseline EEG and MRI but will not participate in any clinical interventions. The investigators will also perform neuroimaging (task fMRI, rsfMRI, DWI, structural MRI) and collect EEG before treatment, to compare patient and control groups, and to obtain neuromarkers that predict treatment response. MRI/EEG Tasks Activation of Negative Valence System. The RDoC recommends "viewing aversive pictures" as a means to activate the Negative Valence System. The investigators will adapt the paradigm that accounted for 40% of CBT outcome variance in which participants viewed blocks of angry or neutral faces. The investigators chose to use a block (rather than an event-related) design because block designs have stronger measurement power for characterizing individuals. Experimental design. Stimuli will be color faces from the NimStim set with angry or neutral expressions. There will be six 15-second blocks per condition, with six faces per block; each face is presented for 1250 ms, followed by 1250 ms of fixation. The task starts and ends with a fixation block, and each pair of face blocks is separated by one fixation block. Two fixed forms are used to counterbalance condition orders. Participants perform a 1-back task by indicating, via button press, the repetition of a face. Activation of Positive Valence System. As reviewed in Significance, there is evidence that the reward system is atypical in SAD. To investigate this further, the investigators will adapt a widely used reward processing task that was developed by Delgado and that is recommended by the RDoC for probing the initial response to reward. Experimental design. Participants play a guessing game to try to win money. Each trial begins with presentation of a "mystery card" displaying a "?" (duration: 1.5s). Participants are told that card numbers range from 1 to 9, and they indicate whether they think the mystery card number on a given trial is more or less than 5 by pressing a button. Feedback (1s) is given immediately after and consists of either (a) a reward (a green up arrow and "$1"), (b) a loss (red down arrow with "-$0.50"), or (c) a neutral outcome (the number 5 and a grey double-headed arrow). A 1 s intertrial interval (ITI) separates the trials. Participants complete two runs, each of which includes four blocks of eight trials: two blocks yield mostly rewards (6/8 trials), and two blocks yield mostly losses (6/8 trials). There are also four 15 s fixations, to facilitate deconvolution of fMRI responses. Activation of Cognitive Control System. Based on encouraging prior findings, the investigators have included a cognitive control task in which pretreatment activation of dorsal anterior cingulate cortex (dACC) predicted response to CBT+SSRI in SAD with 83% accuracy. Experimental design. The task is known as the MSIT. It has four blocks each of two conditions (control and interference). Each block lasts 42 s and consists of 24 trials (1750 ms per trial) in pseudo-randomized order with sets of 3 digits (0, 1, 2, or 3) centrally displayed. One "target" digit differs from the other two (distractors). In the control condition, the distractors are always '0' and the target digit corresponds to its position (i.e., '1' in the leftmost position; '2' in the middle position; and '3' in the rightmost position). Thus, on control trials, the target digit and position are congruent. In the interference condition, the distractors are '1', '2', or '3' and the target digit and position are incongruent (e.g., '1' presented in the rightmost position). Participants indicate if the target digit is '1', '2', or '3' by pressing the response buttons. Ignoring the distractors and the misleading position of the target digit on interference trials requires cognitive control. Our primary hypotheses are that: (1) The investigators will identify patterns of brain activity that distinguish adults with SAD from adults in the comparison group, and that (2) The investigators will be able to identify patterns of brain activity that predict which adults with SAD will (or will not) respond to treatment. The primary outcome measure will be treatment response (defined elsewhere in this registration).