Theory of mind deficits in patients with esophageal cancer combined with depression

AIM: To characterize the two components of theory of mind (ToM) in patients with esophageal cancer combined with depression. METHODS: Sixty-five patients with esophageal cancer combined with depression (depressed group) and 62 normal controls (control group) were assessed using reading the mind in the eyes test, faux pas task, verbal fluency test, digit span test and WAIS IQ test. The depressed group was divided into two subgroups including psychotic depressed (PD) group (32 cases) and nonpsychotic depressed (NPD) group (33 cases). The clinical symptoms of patients were assessed using Beck depression inventory version II and brief psychiatric reacting scale (BPRS). RESULTS: There was a significant difference between the depressed group and the control group on tasks involving ToM social perceptual components (mind reading: t = 7.39, P < 0.01) and tests involving ToM social cognitive components (faux pas questions: t = 13.75, P < 0.01), respectively. A significant difference was also found among the PD group, the NPD group and the control group on mind reading (F = 32.98, P < 0.01) and faux pas questions (χ2 = 78.15, P < 0.01), respectively. The PD group and NPD group performed worse than normal group controls both on mind reading and faux pas questions (P < 0.05). The PD group performed significantly worse than the NPD group on tasks involving ToM (mind reading: F = 18.99, P < 0.01; faux pas questions: F = 36.01, P < 0.01). In the depressed group, there was a negative correlation between ToM performances and BPRS total score (mind reading: r = -0.35, P < 0.01; faux pas questions: r = -0.51, P < 0.01), and between ToM performances and hostile suspiciousness factor score (mind reading: r = -0.75, P < 0.01; faux pas questions: r = -0.73, P < 0.01), respectively. CONCLUSION: The two components of ToM are both impaired in patients with esophageal cancer combined with depression. This indicates that there may be an association between ToM deficits and psychotic symptoms in clinical depression.