The score on Theory of Mind (ToM) tasks predicts a lowering of the global functioning in bipolar disorder (BD) patients. A study found that hypomanic ‘traits” in students are associated with a lowering in ToM abilities.

Our study evaluates the relationship between ToM and subclinical thymic life-time symptoms (depressive or hypomanic found in general population) when effect of the “subclinical psychotic symptoms” are controlled.

The sample gathered 142 undergraduate students. To explore, the relations between thymic and psychotic symptoms versus affective ToM, we used the ‘Reading the Mind in the Eyes Test” (RMET) to assess ToM as well as questionnaires to assess subclinical symptoms: the CAPE-42 (’depressive”, ‘positive psychotic” and ‘negative psychotic” subscales) and the MDQ (number of past symptoms of hypomania). The variables were life-time past symptoms (’thymic” and ‘psychotic” subclinical symptom variables).

When the four predictive variables were entered in a regression, depressive and hypomanic symptoms predicted positively the performances on RMET, while positive psychotic symptoms predicted negatively these performances. Therefore, when we adjust the results on psychotic symptoms, the more the students report thymic subclinical symptoms, the better they perform on RMET.

When they study the relationship between ToM and thymic symptoms, researchers should adjust theirs results on life-time psychotic symptoms, which we found strongly associated with thymic symptoms. We found a probable endophenotype which is inversely related to thymic symptoms in contrary to psychotic symptoms and could explain why the two related disorders (BD and schizophrenia) are distinct, at least in some aspects.