Reduced Sensitivity to Non-Fear-Related Stimulus Changes in Panic Disorder.

Panic disorder (PD) is associated with increased body vigilance and reduced cognitive resources directed at non-fear-related stimuli, particularly in the absence of stimulus-rich environments. To date, only few studies have investigated whether this deficit in PD is reflected in reduced mismatch negativity (MMN), an event-related potential indexing preattentive sensitivity to unexpected stimulus changes. We tested 35 patients affected by PD and 42 matched healthy controls in an oddball paradigm, using frequency and duration deviant stimuli to measure auditory MMN. PD patients displayed reduced duration MMN amplitudes in comparison to healthy controls. No group differences were detected for duration MMN latency, as well as frequency MMN indices. Results support the notion of reduced processing of non-fear-related stimuli in PD patients, particularly with regard to the preattentive processing of sound duration deviants. Additionally, our findings are in line with clinical studies reporting divergent deficits in preattentive processing of frequency and duration deviants.

Fronto-lateral alpha power asymmetry in panic disorder.

Resting state alpha power asymmetry in frontal and temporal regions has been reported in various clinical populations, possibly indicating deficits in prefrontal control. In panic disorder (PD), results regarding alpha asymmetric activity to date have been mixed. This study compared 55 PD patients and 42 healthy controls (HC) with regards to resting state alpha power asymmetry. Our results show more right-than-left fronto-lateral alpha power in PD, whereas at other sites and in HC no significant differences were detected. These results support the notion of altered neurobiological processes in PD that possibly represent a vulnerability to the experience of panic attacks. Further studies are needed to clarify potential causal implications of this finding in the genesis of PD, as well as to specify the functional significance of fronto-lateral alpha power asymmetry in PD.

P50, N100, and P200 Sensory Gating in Panic Disorder.

Panic disorder (PD) has been linked to abnormalities in information processing. However, only little evidence has been published for sensory gating in PD. Sensory gating describes the brain's ability to exclude stimuli of low relevance from higher level information processing, thereby sustaining efficient cognitive processing. Deficits in sensory gating have been associated with various psychiatric conditions, most prominently schizophrenia. In this case-control event-related potential study, we tested 32 patients with PD and 39 healthy controls in a double click paradigm. Both groups were compared with regard to pre-attentive (P50), early-attentive (N100), and late-attentive (P200) sensory gating indices. Contrary to a hypothesized deficit, PD patients and healthy controls showed no differences in P50, N100 and P200 values. These results suggest that sensory gating seems to be functional across the pre-attentive, early-attentive, and late-attentive time span in this clinical population. Given this consistency across auditory sensory gating indices, further research aiming to clarify information processing deficits in PD should focus on other neurophysiological markers to investigate information processing deficits in PD (eg, P300, error-related negativity or mismatch negativity).