**1. Introduction: cognitive impairment in schizophrenic disorder**

There is considerable evidence of the presence of cognitive deficits in schizophrenic disorder that are unfavorably correlated to the daily functioning of these patients [1]. These dysfunctions are present before the beginning of the psychotic symptomatology [2]. Cognitive déficits in schizophrenia affect most of cognitive functions and are especially relevant in: memory and learning; abstraction and executive functions; processing speed and attention [3–7].

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

It is important to point out that there are similar cognitive impairments, in much lower intensity, in close relatives, and these deficits can be considered as potential cognitive endophenotype markers of the disorder [8–13]. From this data, it can be accepted that, in many cases, the effect of these alterations, potentially, may be affecting the functioning of any family nucleus and not only the patient or relative at risk of developing disease.

groups of the same age [6, 31]. These cognitive deficits seem independent of positive symp-

Cognitive Impairment in Schizophrenia: Description and Cognitive Familiar Endophenotypes.…

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Although some early investigations [33] showed that about 27% of schizophrenic patients, after neuropsychological evaluation, could not be considered deficit, in fact, it has been proven that they would continue to present neuropsychological deficit compared to healthy subjects, even matching IQ measurements [34]. This group of patients, without supposed deterioration, would show high levels of premorbid functioning, but once the disease was diagnosed, this would be considerably lower [35]. In addition, discordant monozygotic twin comparisons for schizophrenia suggest that almost all affected twins perform worse on cognitive tests than their unaffected twin [36]. In this sense, it can be safely talked about cognitive deficits in schizophrenic patients although, in any case, it is very likely that their cognitive performance is below than what was expected in the absence of disease. It is also interesting to mention that several authors have found a worse performance in tasks of work memory (especially in visual) and in learning verbal tests and free memories in unaffected monozygotic twin brothers and, even a lesser degree, in not affected dizygotic twin brothers against

It is interesting to point out that many patients have a lack of awareness of cognitive dysfunction. Those who are better aware of their deficits are not associated with a lower use of treatment, nor with a lesser deterioration of executive function. But they do have better results in the rehabilitation of some cognitive domains, in adherence to treatment and in their

The neurocognitive dysfunction affects the ability to perform activities of daily living, impairs the ability to solve social problems [15, 16] and has proved to be the better predictor of reincorporation to activities in social and community settings [43, 44] and, especially, in terms of work rehabilitation and maintenance works [45–48]. These data review the importance of cognitive domains as a reliable scale of clinical improvement [15, 49–52] and, as is to be expected, the degree of cognitive impairment implies a worse adjustment in the quality of life of these patients [52–54]. Some authors also consider cognitive functions as an integral part of the concept of resistance to treatment [55]. On the other hand, several studies emphasize the importance and efficacy of cognitive rehabilitation treatments in early stages of psychosis

As expected with these data, the cognitive alteration in schizophrenia is the current focus of attention for the research of therapeutic strategies, both pharmacological and psychological. Regarding the interventions on cognitive domains, the pharmacological treatment, although it has offered certain results, has not been very encouraging [58], however studies using cognitive stimulation (training in executive skills, memory and other cognitive processes) have

Patients with schizophrenia have, comparing with healthy subjects, problems in performing almost all conventional neuropsychological tests. The most widely affected functions are executive tasks. Memory and attention, in their different modalities, are not the only ones affected, but it is these domains that stand out especially about a generalized cognitive

toms [32] and are maintained throughout the course of the disease.

controls [37–40].

[56, 57].

functional capacity [41, 42].

achieved more hopeful data [59–62].

**2.1. Cognitive domains affected**

These data show the existence of a biological basis, despite the undeniable influence of environmental factors on the development and course of both pathologies. In this sense, the DSMIV-TR [14] notes that: *"Although numerous data suggest the importance of genetic factors in the etiology of schizophrenia, the existence of a substantial discrepancy in the frequency of monozygotic twins also indicates the importance of environmental factors".*

As expected, this cognitive dysfunction has influence in the main aspects of daily life [15]. Respecting the family point of view, there is also a great ignorance of the existence and influence of these cognitive symptoms present in the affected relatives. In general, it is suggested that the psychoeducational programs made for this subject directed to family members provide them with an important first step. These programs provides means in order to understand these factors, which make an important stain in their overall functioning, and therefore, in the daily life of these patients [16–19]. On the other hand, it is important to point out that the same patients do not usually present insight of their deficits, and when they do, although they are usually associated with higher levels of adherence to treatment, they also tend to do so with a loss of self-confidence [20]. This fact indicates that family interventions in the education of cognitive aspects should not only stay there and should also involve a research for solutions of family support in other ways. At this point, it cannot be ignored the effect on the family dynamics of the probable presence (even being slight) of these deficits in any of the relatives of the affected subjects. Their awareness and identification are important in order to carry out a family intervention.
