[Toward a better understanding of fatigue in schizophrenia]

Despite being one of the most common complaints of people with schizophrenia, fatigue remains largely unexplored in this population. The lack of knowledge regarding this complex symptom makes it often underdiagnosed and undertreated in schizophrenia. The aim of this brief perspective review is to outline the potential origins (distinguishing primary and secondary fatigue) and consequences of fatigue and to explore some potential treatments in this population. The current literature in schizophrenia has mainly investigated fatigue as a trait, using a self-administered questionnaire. Beyond this observational approach, which does not allow to capture the symptom in real life situations where high levels of fatigue can emerge rapidly, we propose to consider the state level of fatigue, for instance occurring after a prolonged period of cognitive activity (i.e. mental fatigue). We elaborate on the potential relationships between mental fatigue and negative symptoms of schizophrenia and propose some research avenues to test the effects of acute fatigue on effort intentions and behaviours. The consideration of the multidimensional aspects of fatigue will allow to move beyond the sole pharmacological approach to treat fatigue in schizophrenia. Targeting the cognitive as well as the performance components of fatigue through interventions such as concomitant aerobic exercise - mental training offers attractive prospects to reduce fatigue in this population and minimize its functional negative impact.