Multidimensional Apathy in Psychiatric Pathologies.

Apathy is defined by quantitative decrease in goal-directed activity in comparison to the person's previous level of functioning. Apathy is a transnosographic symptom, prevalent in many neurological and psychiatric pathologies (specifically in schizophrenia and depression), and almost half of patients suffer from it. It is an important source of burden, affecting both personal and occupational life. Despite its high prevalence and negative consequences, no pharmacological or non-pharmacological treatments exist, the underlying mechanisms of apathy being poorly understood. The main aim of the present study is to advance in our knowledge of cognitive and neural mechanisms of apathy by using a multidimensional model of apathy, distinguishing three forms: executive, emotional and auto-activation/initiative. the investigators hypothesize, independently of the pathology (schizophrenia and depression), the existence of different cognitive deficits underlying each of the 3 subforms of apathy. Indeed, according to the predictions of Levy and Dubois' model (2006), executive disorders underlie the cognitive form of apathy. It may be related to lesions of the dorsolateral prefrontal cortex and the cognitive territory of the basal ganglia. Emotional apathy could be due to motivational disorder. Dysfunctions or lesions in the orbital and medial prefrontal cortex and limbic territories of the basal ganglia may underlie this. Finally, the initiative form, may be a mixed form, with both motivational and executive difficulties. Lesions or dysfunctions may affect both the cognitive and limbic territories of the basal ganglia or the anterior cingulate cortex.