Theory Of Mind In Bipolar Disorder Patients And First-Degree Relatives

Bipolar disorder is a severe mental illness with unknown causes.We assessed the theory of mind(ToM)deficits on bipolar disorder patients and first-degree relatives,to explore whether the theory of mind deficits of bipolar disorder can be used as an endophenotype,which is helpful to investigate the cause of bipolar disorder and find appropriate treatment.The main aim of this study was to compare patients with bipolar I disorder and the first-degree relatives and healthy controls in measures of theory of mind(decoding and reasoning).Additional aims were to explore the relationship between theory of mind performance and neurocognitive impairments,also the predictive role of theory of mind with neurocognitive and clinical variables on social functioning.31 manic without psychotic symptoms bipolar I disorder patients,31 first-degree relatives and 30 healthy controls were included.Two test with different components were used to assess theory of mind:Hinting Task,Reading Mind in the Eyes Task.A comprehensive battery of neuropsychological test was administered to all subjects assessing general intelligence,attention,working memory,executive functions,speed processing.The Young Mania Rating Scale,Hamilton Depression Scale,Hamilton Anxiety Scale to assess clinical symptoms,and GAF were also administered to the patients.The patients and first-degree relatives showed significantly lower performance in mental state reasoning(p<0.001),pairwise comparisons showed no statistically significant between the patients and first-degree relatives.Additionally,patients and first-degree relatives had poorer performance compared to control group in working memory,executive functions,speed processing(p<0.05).Differences in Hinting Task still remain statistically significant When the effect of working memory,executive functions,speed processing was controlled for(p<0.001).And it shows that the only factor that had a significant predictive effect on the social functioning of patients with bipolar disorder is the Young Mania Rating Scale(r~2=0.310).Through the above experiments,this study found that manic without psychotic symptoms bipolar disorder patients and first-degree relatives have significant impairments in the theory of mind reasoning component.The mental state reasoning component of theory of mind may be a cognitive endophenotype of bipolar disorder.Theory of mind and neurocognitive are partially independent.The theory of mind is not caused by the impairment of neurocognitive function and may have different neural mechanisms.The score of Young Mania Rating Scale can significantly predict the social functioning of manic without psychotic symptoms bipolar disorder patients.The finding of this study support the hypothesis that ToM dysfunction in bipolar disorder is associated with mood symptoms and it might be a endophenotype of bipolar disorder.However,making inferences based on these results should be in cautious way.