SUN Yi, LI Xiao-yi, YAO Lin-yan, ZHAO Lan, DAI Ning , WU Hao

Background  The etiology and pathology of functional constipation (FC) is unclear. Some researches suggest that psychological factors may be related to this common problem. This study aimed to investigate the relationship between attention processing and emotional status in FC patients compared with healthy controls.
Methods  We investigated selective attention and emotional status in patients with FC using the counting Stroop task. Thirty-five FC patients (FCP group) and 24 healthy controls (HCs) underwent an event-related potential (ERP) study while performing the task. Response time, latency and amplitude of P300 were collected and compared between the two groups. The Hamilton Depression Rating Scale (HAMD-17), Hamilton Anxiety Scale (HAMA), Symptom Checklist-90 (SCL-90) and Eysenck Personality Questionnaire (EPQ) were administered prior to the counting Stroop task.
Results  Scores for the FCP group differed significantly from those for the HCs on the HAMD-17, HAMA, SCL-90 (Global Severity Index, Positive Symptoms Total, dimensions of somatization, obsessive-compulsive, depression, anxiety, and psychosis), as well as extraversion and neurosis dimensions of the EPQ (P <0.05). There was no significant difference in response time or accuracy rate between the two groups (P >0.05). ERP results showed prolonged latency at F4, additionally found enhanced activation at F3, FC1 and T8, and decreased activation at sites FC6 and P7 in the patients with FC. Statistically, significant differences of P300 latency at site F4 (P <0.05) and P300 amplitude at F3, F4, T8, P7, FC1 and FC6 (P <0.05) between the patients with FC and the HC were revealed.
Conclusions  The findings suggest that patients with FC are more susceptible to depression and anxiety, as well as somatization, obsessive-compulsive tendencies and other neurotic personality characteristics. Patients may employ psychological defense mechanisms to avoid the pain of depression and anxiety. ERP results imply there may be some brain dysfunction and attention deficits in patients with FC.