Effects of Theory of Mind on Frequency of Social Interaction in Patients with Traumatic Brain Injury

Poor social functional outcome is common among patients with traumatic brain injury (TBI) even years after the injury. Exploring the main factors contributing social functional outcome will provide useful information for rehabilitation plans, which would help with patient’s social interaction and reduce possible social cost. Previous results supported that TBI patients had poor performances on the faux pas task. This is probably due to their prefrontal lesions that affect their ability to infer others’ thoughts and feelings in social context. However, previous studies neither explore the effect of theory of mind on social functional outcome, nor compare the importance of theory of mind with executive function and verbal comprehension intelligence.
Thirty mild, moderate and severe TBI patients as well as twenty nine normal controls participated in the present study. All TBI patients’ brain computed tomography or magnetic resonance imaging showed abnormal findings. Each participant received a battery of neuropsychological tests and the faux pas task. TBI patients and their families also completed a social functional outcome questionnaire that had been revised and validated in Taiwan in pilot study. Current score and change score of social function outcome were both measured.
The results revealed that both mild TBI patients as well as moderate and severe TBI patients had significantly poor performance on the social functional outcome questionnaire than the control group. Meanwhile, they performed significantly poorer on the social functional outcome than they did at the pre-morbid state. Performance scores of the faux pas task and the verbal comprehension intelligence test were significantly contributory to the patients’ self ratings of the current score and the change score of the social functional outcome questionnaire, accounting for 51％ ~ 52％ of the variance. However, only the verbal comprehension intelligence test significantly contributed to the family measures’ ratings of the current score and the change score of the social functional outcome questionnaire, accounting for 22％ ~ 33％ of the variance.
Based on the results, TBI patients had significantly lower frequency of social interaction after injury regardless of the severity resulting from the impairment of verbal comprehension intelligence and theory of mind. It is thus suggested that neuropsychological assessment including the tests of theory of mind and verbal comprehension intelligence could directly link to proper rehabilitation plans to improve patients’ social functions.