Frontal lobe functions in schizophrenia: Interest of the Stuss approach.

OBJECTIVE: The term Executive Functions (EFs) refers to the higher-level skills we use every day to control and coordinate our cognitive abilities and behaviours. EFs are mainly supported by the frontal lobes and its connections. EFs are frequently impaired in schizophrenia, but the profiles of executive deficits accompanying schizophrenia remains unclear. The use of specific EFs models might help to shed new light on this issue. Stuss (Stuss & Alexander, 2007; Stuss, 2008, 2011, 2017) proposed an integrative and operant model of EFs which has never been used to explore and characterize deficits in schizophrenia. The aim of this study is to further examine EFs in schizophrenia in the light of the frontal lobe functional approach developed by Stuss (2008, 2011, 2017) in order to question EFs impairment homogeneity and heterogeneity in schizophrenia. METHODS: Forty-five patients with schizophrenia and fifty-five healthy controls were recruited. They all completed a series of neuropsychological tests selected and adapted to measure the five majors' functions of the frontal lobe described by Stuss (2017). RESULTS: Patients showed deficits in almost all the frontal functions. Inside each frontal lobe function, correlations were observed between all the corresponding measures. The study of profiles highlighted a heterogeneous functioning in schizophrenia. CONCLUSIONS: The model of Stuss (Stuss & Alexander, 2007; Stuss, 2008, 2011, 2017) allows accurate and specific measures of the frontal functions and observation. Beyond "cold" or "hot" EFs division, this integrative approach is helpful to understand links within neurocognition.

The use of the French Dimensional Apathy Scale (f-DAS) to assess apathy in schizophrenia: Properties and profiles.

BACKGROUND: Apathy can be defined as a quantitative reduction of self-generated voluntary and purposeful (or goal-directed) behaviour. The literature underlines the triadic dimensional nature of apathy, but in schizophrenia there are inconsistencies due to difficulty in assessment. The Dimensional Apathy Scale (DAS) and its validation into French (f-DAS) provide measurement of three neurobehavioral apathy subtypes: Executive, Emotional and Initiation, but these subtypes have never been explored in schizophrenia. OBJECTIVE: The aims of this study are to assess apathy in schizophrenia with a tri-dimensional tool (the f-DAS), to examine its psychometric properties in schizophrenia and the apathetic profiles of patients with schizophrenia. METHODS: One hundred and ten subjects were recruited. Forty-five belonged to the patients' group and fifty-five to the control group. They all completed the Mini-International Neuropsychiatric Interview (M.I.N.I), the French National Reading Test (f-NART), the French Dimensional Apathy Scale (f-DAS), the Lille Apathy Rating Scale (LARS) and the Beck Depression Inventory (BDI II). RESULTS: Regarding the total score of the f-DAS and the subscores for each dimension, patients appeared significantly more apathetic than healthy controls. Consistency, validity, concurrent and divergent validity were good. In the patient group, several profiles of apathy were identified. CONCLUSIONS: The f-DAS has good psychometric properties and provides reliable and valid dimensional assessment of apathy in schizophrenia. From a dimensional point of view, using the f-DAS we demonstrated that prevalence of apathy could be underestimated in schizophrenia. Patients with schizophrenia are more impaired on the Executive and Initiative dimensions of apathy.