Emotional Intelligence (EI) refers to the ability enabling people to experience, express, perceive, and understand own feelings as well as those of others. Though it is not a distinct social cognitive domain, EI can be assigned to the emotion processing part of social cognition.
Previous studies using the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT) to measure EI performance in schizophrenia patients have found consistent impairments compared to healthy control subjects. A recently published study also revealed impairments in first degree relatives of schizophrenia patients, supporting the theory that EI may be an endophenotype for schizophrenia. On the basis of correlation analyses showing at most moderate correlations between EI and non-social cognition, the MSCEIT is regarded as sufficiently independent from non-social cognitive functions. However, the influence of non-social cognition on the group difference in EI between schizophrenia patients and healthy subjects has not yet been investigated. To close this gap, the current study investigated both EI and non-social cognition in schizophrenia patients and control subjects by using the MSCEIT and the Brief Assessment of Cognition in Schizophrenia (BACS), respectively. In order to clarify whether EI may represent a marker of risk for schizophrenia we further investigated a group of unaffected siblings of patients. 56 patients suffering from schizophrenia, 57 unaffected siblings of schizophrenia patients as well as 127 healthy control subjects were included into the study. Compared to healthy control subjects, patients scored significantly lower in most MSCEIT branches and in all subtests of the BACS. Adjustment for non-social cognition (BACS composite score) and education substantially diminished the difference in EI performance between groups. Merely the difference in the “managing emotions” branch of the MSCEIT remained significant. Next to similar performance patterns in the BACS unaffected siblings of schizophrenia patients and control subjects showed comparable EI levels, thereby indicating intact EI in non-affected relatives of schizophrenia patients. In summary, EI as measured with the MSCEIT does not seem to represent a genetic marker of risk for schizophrenia and non-social cognition is largely responsible for poor MSCEIT performance in schizophrenia patients.