Altered brain–behavior coupling during inhibitory control in ankylosing spondylitis: ERP evidence from NoGo-P3 component

BACKGROUND: Cognitive dysfunction has increasingly been recognized in Ankylosing Spondylitis (AS), yet the neural mechanisms underlying inhibitory control in this population remain insufficiently characterized. Rather than reflecting a simple global deficit, cognitive alterations in AS may involve task-dependent changes in the coupling between neural activity and behavioral performance. This study examined executive control in AS using a Go/NoGo paradigm and focus on brain-behavior coupling during inhibitory processing. METHODS: 16 male patients and 23 age-matched healthy controls completed a Go/NoGo task while undergoing 32-channel EEG recording. ERP analyses focused on N2 (200-300ms) and the late positive component in the NoGo condition (hereafter termed NoGo-P3; 400-600ms). Mean amplitudes were extracted at fronto-parietal midline electrodes. To directly test group differences in brain-behavior coupling, linear regression models including the ERP × Group interaction term were fitted. Theta-band (4-7 Hz) power within the 400-600 ms window was additionally analyzed using FFT-based spectral estimation. RESULTS: Behaviorally, AS patients showed lower Go accuracy and longer Go reaction times, together with a tendency toward higher NoGo accuracy. In AS patients, NoGo accuracy positively correlated with NoGo-P3 amplitude at FCz (r = .64, p = .009) and Cz (r = .55, p = .035), whereas these associations were not significant in controls. Direct group comparison showed a significant ERP × Group interaction at FCz (b = 0.084, p = 0.033), indicating that the relationship between NoGo-P3 amplitude and inhibitory accuracy differed between AS patients and healthy controls, while Cz (b = 0.051, p = 0.106) showed a similar but non-significant trend. Complementary theta analyses revealed enhanced post-stimulus theta power in centro-parietal regions during NoGo processing in AS. CONCLUSIONS: The findings suggest altered brain-behavior coupling during inhibitory control in AS, with the most robust evidence emerging from the NoGo-P3 component at FCz. This pattern is consistent with greater reliance on effortful control-related neural recruitment during successful inhibition and may represent a candidate electrophysiological marker of altered executive processing in AS.