Despite decades of refining traditional treatments for schizophrenia-spectrum disorders, recovery rates remain unchanged at only 13.5%, and there is an urgent need for innovative new interventions. Cognitive behavioural therapy has more recently been applied to treating psychosis and initial evidence has suggested that cognitive behavioural therapy for psychosis (CBTp) is the most effective psychosocial intervention available for psychosis. However, the efficacy of CBTp has been limited to moderate effect sizes. Little is currently understood about the mechanisms of CBTp, and a greater understanding of mechanisms is necessary in order to improve treatment efficacy. Despite overwhelming evidence for neurocognitive and neurophysiological factors involved in the etiology of psychosis, these factors have never been examined as mechanisms of improvement from CBTp. Cognitive behavioural therapy for psychosis (CBTp) has demonstrated efficacy for reducing positive symptoms, negative symptoms, and improving community functioning6 for individuals diagnosed with psychotic disorders. Despite meta-analytic evidence for the efficacy of CBTp, little is known about the neurophysiological processes through which symptomatic and functional change occurs. Electroencephalography (EEG) provides temporally precise measurement of neurophysiological activity. Positive symptoms have been associated with reduced integration of discrepant information as indexed by the N400 event-related potential, reduced resting state power in the EEG alpha frequency band, and reduced cognitive control as indexed by EEG alpha and theta power during cognitive flanker tasks. Additionally, neurocognitive abilities such as attention, memory, and problem solving are the best predictors of community functioning among individuals diagnosed with psychotic disorders. Although CBTp improves community functioning,\[6\] neurophysiological and neurocognitive outcomes have never been examined as therapeutic mechanisms from CBTp, despite the fact that therapeutic processes would be expected to improve cognitive functions.
Aim 1: Examine neurophysiological outcomes from CBTp using EEG.
Aim 2: Examine neurocognitive outcomes from CBTp
Hypothesis 1: After CBTp it is expected that participants will have a) increased N400 amplitude; b) increased resting state EEG alpha power; and c) reduced alpha and increased theta power during a flanker task
Hypothesis 2: After CBTp participants will have increased global neurocognitive abilities as indexed by a neurocognitive composite score.
Although CBTp has demonstrated efficacy to improve symptoms for individuals experiencing psychosis, little is known about the neurophysiological process through which this improvement occurs, and neither EEG nor neurocognitive outcomes from CBTp have ever been examined. The current results will provide preliminary evidence for neurophysiological mechanisms of change from CBTp that will increase understanding of the disorder and provide critical insights for refining psychotherapeutic interventions. Additionally, psychotherapy trials typically only examine psychological outcomes, however, if CBTp is effective it would be expected that this could be detected at both the neurophysiological level and neurocognitive level as well. My incorporation of multiple levels of assessment in clinical trials was recently praised as a goldstandard approach to trial methodology. This line of research is critical to improving the efficacy of CBTp.
