Background

Up to now, studies have not demonstrated significant efficacy of antipsychotics on cognitive impairments in patients with psychotic disorders. These cognitive deficits are of particular interest since they traditionally start early before the diagnosis of psychosis. They are observed during premorbid and prodromal stages, and during the first episode of psychosis. Moreover, cognitive impairments may be detected without any psychotic symptoms (such as positive symptoms) suggesting their development independently of the psychotic symptoms. Cognitive disturbances consist of impairments of episodic and working memories, intellectual functioning, executive functions (planning, inhibition, and cognitive flexibility), selective and sustained attentions and social cognition (emotion, recognition, theory of mind). The altered cognitive functions observed in schizophrenia are the same as in earlier stages but at a lower level of severity.

Literature findings

Data suggest that cognitive deficits can be considered as vulnerability markers of psychosis since they have been described in healthy relatives of psychotic patients with high genetic risk. Cognitive deficits might also be considered as predictive of the occurrence of the disease after the first episode of psychosis. Indeed, retrospective studies suggest cognitive impairments in patients with schizophrenia during premorbid and prodromal phases but not in bipolar patients. Cognitive assessment might be of particular interest in people at risk for psychosis, in order to differentiate diagnostic outcomes. Cognitive functioning impairs until the diagnosis of first episode psychosis, even though cognitive profiles are quite heterogeneous in these patients. Once the diagnosis of schizophrenia is considered, cognitive deficits may be stable, although the literature is still controversial. Several factors such as symptoms and gender can contribute in diversifying the cognitive profiles. Moreover, age of onset might worsen the prognosis because of a disruption of the cognitive development and the disturbance of scholarship in young individuals.

Discussion

Considering these results, the treatment of cognitive deficits should be initiated as soon as possible, e.g. in people at risk for psychosis in order to reinforce the normal cognitive development, prevent cognitive decline and to preserve the educational, professional and social status. Since antipsychotic medications do not impact on cognitive functioning, alternative therapeutics should be developed such as cognitive remediation. Several studies and meta-analyses have shown that cognitive remediation programs are particularly efficient in patients with schizophrenia or bipolar disorders. Contrary to antipsychotics, these techniques should be used in patients with a first psychotic episode, but also in individuals with subpsychotic symptoms, subthreshold to the diagnosis of schizophrenia.