Auditory Preattentional Processing Among Patients With Panic Disorder: An Event-related Potential Study

Objective: Panic disorder (PD), also known as acute anxiety, is characterized by recurrent panic attacks. The core feature of PD is panic attack that is seemingly sudden, unexpected. With the development of the disease, patients have an extensive use of medical services, an impaired social and work life, and an overall reduced quality of life. Based on theoretical evidence and symptom of panic disorder, neuropsychological studies suggest that cognitive abnormalities of information is one of the main features of panic disorder and PD patients exhibit information automatic processing disorder.The mismatch negativity (MMN) is an endogenous ERP (event-related potential) component that is elicited by any discriminable change in auditory stimulus stream. Since MMN is elicited in the absence of attention, it is frequently assumed to reflect the pre-attentive memory-based automatic processing. The aim of the present study is to investigate the preattentive automatic information processing in PD patients and to examine whether the sound different physical attributes are specific to panic disorder. In particular, the multi-feature paradigm was used in this study.Method:15 PD patients(8 females, all right-handed)and 15 age and gender matched healthy volunteers(9 females, 1 left-handed) with an age range of 18–60 participated in this study. For diagnostic purposes, the Structured Clinical Interview for DSM-IV (SCID) was performed[1]. All patients met DSM-IV criteria for panic disorder with or without agoraphobia. Patients and normal healthy participants are required to complete the 14-item Hamilton Anxiety Rating Scale (HAMA-14). The patients also completed the Panic Disorder Severity Scale (PDSS). The multi-feature paradigm was used to enable the recording of MMNs. Stimulus sequence consisted of five deviants ( sound frequency, intensity, location, duration, gap) and standard stimulus, furthermore, there were two levels in the first three deviants (±10% frequency;±10dB intensity; left or right location). The five deviants and standard stimulus are 50% respectively. In the recording process, subjects watched movies with silent sound, ignoring the sound from headphones. A 64channel electroencephalogram was recorded. After off-line analysis, the different deviant amplitudes of mismatch negativity were measured at fronto-central electrodes. Mean amplitudes and peak latency were subjected to ANOVAs for repeated measures. Pearson correlations were performed between the magnitudes of the MMNs for each deviant and HAMA, PDSS scores.Results:1.The MMN amplitudes elicited by sound intensity(F(1,28)=4.207, P=0.05)and location(F(1, 28)=8.155, P=0.008)were significantly increased in PD patients compared to the controls.2. There was the main effect of deviant type (F(7,196)=7.519, P<0.01) in both groups. maximum amplitudes was intensity deviation(M=–1.456±0.159), The minimum amplitudes was gap deviant(M=–0.208±0.135).3. Frontal MMN amplitude was significantly increased than the central are(aF(1, 28)=136.363, P<0.01)in both groups.4. Pearson correlation analysis indicated that a significant correlation between MMNs amplitudes and PDSS scores(r = -0.619 p < 0.05). For each deviant types, only the MMN amplitude for the higher intensity deviations(r = -0.584; p < 0.05) and gap deviants(r=-0.637, p<0.05) showed significant.Conclusion:1. PD patients exhibited enhanced preattentive automatic processing for auditory physical attributes.2. Dysfunction of both intensity and location automatic processing may be specific for PD patients.3. Severity of PD patients enhanced pre-attentive change detection and associated autonomic reaction. It was possible that increasing severity of PD patients were more likely to affect physiological responses to sound higher intensity and gap.4. The frontal distribution was more major areas than that of central for automatic processing of physical information in both groups.