Cognitive problems have long been considered a core component of schizophrenia but have only recently been considered as possible diagnostic features of the illness or as potential treatment targets.

The cognitive impairment tends to be more independent of the typical clinical symptoms of schizophrenia than similar problems in the affective disorders. Recently it has become apparent that there are some aspects of impaired neurocognition that are consistently found in schizophrenia and may have both prognostic and treatment implications for clinical practice. Neurocognitive impairment symptoms are present prior to the initiation of antipsychotic treatment.

Schizophrenia was mostly considered as neurocognitive disorder.

Schizophrenic patients in recent studies perform an average of 1.5 to 2 standard deviations below healthy controls on many neurocognitive tests and this impairment is greatest in the domains of memory, attention, working memory, problem solving, processing speed, and social cognition. Specific aspects of cognitive dysfunction are different from hallucinations, delusions, and paranoia and they are largely unrelated according to CATIE study.

Functional magnetic resonance imaging (fMRI), positron emission tomography (PET), electroencephalogram (EEG) and even structural MRI studies all show relations between neuroanatomical measures and cognitive deficits in schizophrenia. These relations are strongest in frontal regions, temporal cortex, and hippocampus.

Clinical assessment of cognitive functioning in schizophrenia and proposal for including of cognitive dysfunction as diagnostic criteria in DSM-IV.

The treatment of cognitive deficits, the most beneficial method for patients.