Effects of a Mindfulness-Based Intervention on Event-Related Potentials (P3) and Depressive Symptoms in Oncological Patients.

Objective: The aim of this study was to investigate changes in P3 amplitude and latency to emotional stimuli with different arousal and valence levels after a mindfulness-based intervention in oncological patients. Methods: P3 amplitude and latency at Fz, Cz, and Pz to emotional salient stimuli differing in valence (positive vs. negative) and arousal (low vs. high) levels were measured in 17 oncological patients (M_age = 51 years, SD = 9.17, females = 11) before and after a mindfulness-based intervention in a waitlist-controlled clinical trial. Group sessions were held 2x/week over a period of 5 weeks. Results: Arousal and valence levels of emotional salient stimuli were significant modulators of P3 amplitudes (P = .050; P = .006, respectively). P3 amplitudes at Fz decreased significantly from pre-waitlist to post-intervention (P = .002). P3 latency for negatively valenced stimuli decreased from pre- to post-intervention with trending significance (P = .080). P3 latency at Pz showed a trend of being shorter than P3 latency at Cz (P = .066). Depressive symptoms showed a decreasing trend from pre- to post-treatment (P = .075). Conclusions: We could show that arousal and valence levels of emotional salient stimuli are important modulators of P3 amplitudes and latencies in oncological patients. P3 amplitudes at Fz decreased significantly from pre-waitlist until after mindfulness-based intervention, decreases from pre-to post-intervention were linear, but not significant. In oncological patients the mindfulness-based intervention seems to have its strongest effect on the frontal electrode Fz, not the electrode Pz where its amplitude was largest. Depressive symptoms could be reduced.