Event-related and oscillatory electroencephalography (EEG) biomarkers have been demonstrated to predict full-course treatment gains in focal and global cognitive ability in treatment refractory schizophrenia, according to study results published in Schizophrenia Research.
Cognitive and psychosocial impairment in schizophrenia may be caused by deficits in early auditory information processing (EAIP). Auditory-based targeted cognitive training (TCT) may improve EAIP and contribute to reductions in clinical symptoms and improvements in cognition and psychosocial functioning. Although TCT has been shown effective at the group level, this therapy produces varied response rates; however, EEG biomarkers of EAIP have been promising at producing malleable change secondary to TCT. The objective of the researchers in this study was to evaluate and characterize the relationship between oscillatory EEG activity and TCT outcome.
Study researchers recruited patients with chronic schizophrenia or schizoaffective disorder from a residential treatment program and assigned each person to receive either treatment as usual (TAU; n=22) or TAU with TCT (n=30). They collected data during a passive auditory oddball paradigm consisting of a standard stimulus and 5 distinct types of deviant stimuli: 1 duration deviant of 125 ms at 1000 Hz and 4 novel pitch sweep deviants designed to reflect TCT modules with the same name. All patients underwent EEG at baseline and after the study ended. Investigators used near-mix models to assess sensitivity of oscillatory EEG secondary to TCT and used regression models for TCT and TAU.
Results revealed that theta evoked power at baseline predicted improvements in global cognitive function among patients who underwent TCT (R²=0.19, β=0.44, F [1,20]=4.53, P =.047, 95% CI, 0-0.023) but not among patients who underwent TAU (R²=0.006, β=0.076, F [1,18]=0.099, P =.76, 95% CI, −0.14 to 0.019). Theta also evoked phase locking to duration at baseline, which predicted improvements in global cognitive function among patients who underwent TCT (R²=0.19, β=0.43, F [1,20]=4.33, P =.05, 95% CI, −0.16 to 55.76) but not among patients who underwent TAU (R²=0.011, β=0.1, F [1,18]=0.19, P =.67, 95% CI, −29.77 to 45).
Among patients who underwent TCT, sensitivity in sweep deviant theta evoked power (R²=0.19, β=−0.44, F [1,20]=4.47, P =.048, 95% CI, −0.053 to 0) and theta evoked power to the sweep deviant difference waveform (R²=0.21, β=−0.46, F [1,20]=5.09, P =.036, 95% CI, −0.057 to −0.002) to result in a significantly predicted improvement in verbal learning. Analyses demonstrated 83% sensitivity and 67% specificity in detecting improvements in global cognition and 91% sensitivity and 80% specificity in detecting improvements in verbal learning secondary to TCT.
This study had 2 main limitations. First, findings may not apply to patients with early illness or less impairment given the heterogeneity of patients and possible secondary impacts on TCT. Second, attrition was higher among patients who underwent TCT compared with TAU; therefore, it is possible that the higher attrition rate was secondary to the higher time demands required for daily participation in TCT rather than the intervention itself.
The study researchers concluded that the integrity of baseline neurophysiologic activity associated with EAIP may reflect a positive therapeutic response underlying the efficacy of TCT that may be useful in predicting the treatment response in treatment-resistant schizophrenia; however, they acknowledge that “replication and validation on a more robust sample is needed before any firm conclusions can be drawn.”
Disclosure: One study author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Hochberger WC, Thomas ML, Joshi YB, et al. Oscillatory biomarkers of early auditory information processing predict cognitive gains following targeted cognitive training in schizophrenia patients [published online November 20, 2019]. Schizophr Res. doi:10.1016/j.schres.2019.11.015