Emotional dysregulation in individuals with high borderline personality features: an electrophysiological study of resting-state and task-state EEG

Objective High borderline personality features (H-BPF) are dominated by emotional dysregulation. This study aimed to explore the neuroelectrophysiological mechanisms of emotional dysregulation via electroencephalography (EEG), and provide empirical evidence for understanding the neural basis of this population. Methods Participants completed the difficulties in emotion regulation scale–16 (DERS-16). Resting-state EEG (RsEEG) was recorded to analyze prefrontal spectral power. A modified emotional face color-discrimination task combined with event-related potential (ERP) and time-frequency analysis was adopted to compare behavioral performance, P300/LPP components and prefrontal theta activity between groups. Results Experiment 1 included 75 participants (H-BPF: n = 33; healthy controls (HC): n = 42) and revealed that the H-BPF group scored significantly higher on the DERS-16 compared with the HC ( t = 16.491, p < 0.001). RsEEG data showed that the H-BPF group exhibited significantly higher power in the prefrontal delta ( t = 2.765, p = 0.008) and alpha ( t = 2.145, p = 0.034) bands. Experiment 2 included 80 participants (H-BPF: n = 36; HC: n = 44) and demonstrated that the H-BPF group had significantly longer reaction times in the task ( F (1, 78) = 6.025, p = 0.011, η 2 p = 0.072) without group differences in accuracy. ERP results showed that LPP amplitude exhibited a significant group-by-electrode interaction: compared with the HC group, the H-BPF group showed reduced LPP at fronto-central sites but enhanced LPP at parieto-occipital sites (all p < 0.05). Time-frequency analysis revealed significantly higher prefrontal theta power in the H-BPF group ( p < 0.05). Conclusion H-BPF individuals show marked emotional dysregulation and exhibit elevated prefrontal delta and alpha activity at rest. During emotional interference tasks, they show impaired late emotional regulation: excessive prefrontal theta oscillations and reduced frontal control, coupled with enhanced parieto-occipital activation, leading to lower behavioral efficiency. This study identifies a dual pattern of altered resting-state neural activity and task regulatory deficit, providing electrophysiological insights into emotional dysregulation among individuals with H‑BPF. Clinical trial number Not applicable.