Effect of computerized cognitive training on P300 ERP impairments in Indian patients with schizophrenia

This study investigates the neurophysiological effects of a 3-month computerized Cognitive Training (CT) program on P300 Event-Related Potential (ERP) abnormalities in Indian patients with chronic schizophrenia. Twenty-nine patients were enrolled from the DART facility at GMCH, Chandigarh, and randomized into CT or Treatment-As-Usual (TAU) groups. Participants in the CT group underwent structured cognitive retraining sessions targeting domain-specific deficits, while TAU participants continued routine clinical care. ERP data were recorded via a visual oddball paradigm, and processed using EEGLAB and ERPLAB. Time-frequency decomposition was performed using Discrete and Continuous Wavelet Transforms to assess spectral dynamics. Statistical analysis revealed a significant Treatment × Time interaction for P300 latency at the frontal (Fz) region (F = 5.095, p = 0.034), indicating a notable reduction in cognitive processing delay in the CT group. This latency reduction was significantly correlated with improvements in neuropsychological measures of processing speed. However, no significant interaction was found for P300 amplitude, suggesting limited modulation of attentional resource allocation. Spectral analysis further revealed an increase in theta power within the P300 latency window post-training in the CT group, potentially supporting enhanced cognitive engagement. Conversely, elevated alpha synchronization during task performance indicated ongoing difficulties in neural suppression mechanisms under attentional load. No significant changes were observed in overall band power across groups. These findings suggest that while short-term CT can enhance processing speed in schizophrenia, attention deficits may persist. Longer and more intensive cognitive remediation protocols may be necessary to achieve broader cognitive and electrophysiological improvements.