Our topic is regarding schizophrenia. We are going to specifically write about cognitive control in schizophrenia. If we briefly define cognitive control that is an ability to change information processing and people’s behaviors for current aims (Badre, 2008; Dreisbach, 2012; Miller, 2000; Miller and Cohen, 2001; Veen and Carter, 2006).
Although the prevalence of the disease is low among societies, it is a popular area for researchers. However, schizophrenia is not a simple disease at the present time. It is a severe mental disorder because of many different factors that play a role in the etiology, being different clinical types, showing diversity in the progress and endpoint, patients living in his own inner world, and impairments in thoughts, emotions, and behaviors which are seen as significant problems.
Therefore, it is a serious disease that is supposed to be considered. The fact is that it starts at a young age, and causes long-lasting negative effects on both the patients and their families and the difficulty of the acceptance of the disease in the society aggravates the social aspect of the disease.
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On the recorded history, observed symptoms and made definitions were frequently found in schizophrenic patients. Written documents describing schizophrenia can be traced to the ancient Pharaoh of Egypt. Depression, dementia, and thought disorders are typical of schizophrenia and described in detail in the Hearts Book. Heart and mind seem to be synonymous in ancient Egypt.
Schizophrenic patients were the cruelest victims of scholastic understanding in the middle ages. The patient was thought to have an evil so they’ve seen heavy oppression. From the 17th century onwards, Willis Pinnel, John Haslam, Morel, Hecker, Kahlbaum, Kraepelin worked on schizophrenia and developed the scientific basis of the disease.
One of the first people to differentiate mental disorders into different categories was the German doctor, Emile Kraepelin. He defined the term ‘‘dementia precoxe’’ in 1874. He was the first to make a distinction between dementia praecox and manic depression.
Also, Eugen Bleuler introduced the term ‘’schizo-phrenia (mind division)” to literature in 1911 and he was also the first to describe the symptoms: positive or negative. Today, schizophrenia is usually described in terms of positive and negative symptoms. Delusions, hallucinations, disorganized thought/nonsensical speech, and bizarre behaviors are called positive symptoms.
Hallucinations
Sensory perceptions related to hearing, vision, taste, smell, and touch that are not perceived by anyone else and that do not actually exist. ‘’Voices’’ are the most common types of hallucinations in schizophrenia and these sounds can tell patients about their behavior, give orders to the patient about their movements, and warn against an event.
Delusions
It is wrong thoughts that cannot be corrected. People with delusions believe that they are true to thoughts that have no validity and patients with schizophrenia often think that others control their movements with magnetic waves, they believe television or radio broadcasts are used to convey special messages to them.
Disorganized Thoughts
The patient is confused about what to say and how to say. These thoughts, which are scattered in their minds, can cause unclear conversations in patients.
Bizarre Behaviors
Patients with movement disorders may repeat a certain movement continuously and may lead to catatonia if they are more extreme. Some schizophrenic patients may experience these symptoms, which prevent them from performing their social, professional functions.
On the other hand, flat affect, reduced in social interaction, no feeling of enjoyment (anhedonia), less motivation (avolition), speaking less (alogia) and moving less (catatonia) are called negative symptoms. Negative effects lead to deterioration of emotions and behaviors. Patients with these symptoms need support in order to manage their daily work and they often ignore simple personal care.
Patients can be perceived as lazy or unwilling by their environment so negative symptoms may cause incorrect detection. It is very important that the relatives of the patients follow these symptoms. Apart from that, in this review article, cognitive control in schizophrenia such as functional network changes, lateral prefrontal cortex, self-esteem and health locus of control, and episodic memory in schizophrenia will be discussed by examining several articles.
Many articles have been written on cognitive control in schizophrenia. In each article, schizophrenia is discussed in another way and this has sometimes led to controversy. In one of the articles we read, there has been increasing attention to cognitive dysfunctions in schizophrenia during recent years and so there has been an increase in the studies about this subject.
According to the results, ‘’ Yet there is no specific cognitive dysfunction area in schizophrenia has been found like in Alzheimer disease but it is shown that the cognitive dysfunctions are among the core symptoms of schizophrenia and they are not the consequence of other schizophrenic symptoms.’’ (Kayahan et al. 2004). Cognitive disorders are the most common symptoms of schizophrenia. Based on the various research, it has been observed that the severity of cognitive disorders in schizophrenia is higher than the cognitive deficits in neurodegenerative diseases.
In the study, some disorders were found about the functions of memory in schizophrenia, active memory, executive functions. In addition, cognition dysfunctions are so important because it is one of the important factors that determine the course and termination of schizophrenia. More severe cognitive impairments were found in the patients. They have been shown to be more chronic, not responding to treatment and more psychosocial dysfunctions.
In the first research we examined, Ray et al. (2017) supported that in schizophrenic patients’ PFC regions, there would be less functional connectivity no matter what task demands are and more connectivity reductions regarding cognitive control processes. They had two groups, healthy adults and schizophrenic individuals, to examine this issue. The groups are assessed according to two tasks, the RISE episodic memory task and DPX goal maintenance task, for cognitive control. After that, they made inferences about the functional connectivity of two groups. They found that according to the conclusion of the research, impairments in FPN are especially related to individuals who are schizophrenic and there are dysfunctions in cognitive control that cause higher cognitive deficits in the disease.
In addition, in schizophrenic patients’ brains, there are some regions, the bilateral MTL, right DLPFC, left precentral gyrus, and left anterior PFC, that seem to have an important role in cognitive control deficits.
In another study, Barbalat et al. (2009) found that schizophrenic patients had more errors than healthy subjects when information transported by episodic and contextual signals increased.
In the study, it was seen that the impairments were relevant hypoactivation in caudal LPFC regions, and rostral LPFC regions, respectively. When they analyzed the results of fMRI scans, in healthy group, a contextual effect was exhibited by frontal regions, but not episodic effect and that was found in the caudal LPFC, Brod-mann area 9, 44, and 45, inferior and middle frontal gyrus, and pre-motor cortex, Brodmann area 6 and middle frontal gyrus, bilaterally.
Conversely, an episodic effect was shown by frontal regions, but not contextual effect and that was found in the rostral LPFC, Brodmann area 10 and 46, inferior and middle frontal gyrus, bilaterally. Though in the schizophrenic patient group, a contextual effect was exhibited by frontal regions, but not episodic effect and that was found in the caudal LPFC and in the left premotor cortex, the peaks are not significant with P= .09, bilaterally. Conversely, an episodic effect was shown by frontal regions, but not contextual effect and that was found in the rostral, caudal, and premotor regions, bilaterally.
In another research, John et al. (2015) suggested that schizophrenia gives different impairments to DLPFC and VLPFC in the control of episodic encoding. In the study, they had two groups, schizophrenic and healthy participants, in their study.
According to the results of the study, differentially, schizophrenic participants were less successful in remembering target versus non-target stimuli and retrieval difficulties correlated with dsymptoms that are disorganized. In the condition of the target versus non-target contrast, VLPFC was activated and correlated with retrieval success for two groups.
Conversely, in the condition of the non-target versus target contrast, DLPFC was activated more in the control group than in the patient group and correlated with performance in the control group, solely. After that, they concluded that the VLPFC can be used by schizophrenic individuals to get control over semantic encoding in a successful way but they particularly are impaired at using the DLPFC for task-appropriate encoding. Thereby, schizophrenic individuals have improved memory for target versus non-target items.
In addition to all, other research, the authors’ purpose of this study is that investigate the relationship between neurocognitive factors, self-esteem, health locus of control, and sociodemographic factors in patients with schizophrenia. In this study, it is argued that there is a relationship between these factors.
The study included people with schizophrenia and control group: forty-six schizophrenic patients and 31 healthy individuals from the community and hospital. All subjects first participated in some surveys such as self-esteem questionnaire, health locus of control questionnaire, and a series of neuropsychological measures.
The mean age of the patient group and the healthy control group were 41.3 years (SD =8.9 years) and 48.7 years (SD =15.7 years). According to the results of multiple regression analysis, inhibition of attention and external health locus of control is decisive for self-esteem. (r=-0.30, P<0.05; r=0.41, P<0.01). Also, two factors were found to contribute to the internal health locus of control: inhibition of attention and external health locus of control (r=-0.43, P<0.01; r=0.61, P<0.001).
In addition, another factor related to external health locus of control was found, which was education (r=-0.31, P<0.05). The education level of the majority of the patient group was high school (65.2%) and 69.6% were single. Most of the healthy control group had a university degree (64.5%) and 74.2% were married. However, the overall predicted variance was small. This study is not sufficient for the ultimate results so more research is needed about the necessary variables related to self-esteem and health locus of control in schizophrenia.
In conclusion, ‘’schizophrenia’’ is a serious and important disease even though it is low among societies so this disease should not be ignored. In this review, some research was read and assessed. The effects of cognitive control on schizophrenia were investigated. Different roles of ventrolateral prefrontal cortex and dorsolateral cortex in episodic memory were found in schizophrenia. Also, it was seen that the lateral prefrontal cortex plays an important role in cognitive control in schizophrenia.
Another important point is the effects of self-esteem and health locus of control in schizophrenia and was seen that inhibition of attention and external health locus of control is decisive for schizophrenic patients’ self-esteem. It was seen that there were impairments that were relevant with hypoactivation in caudal LPFC regions, and rostral LPFC regions.
On the one hand, in schizophrenic patients’ brains, the bilateral MTL, right DLPFC, left precentral gyrus, and left anterior PFC seemed to have an important role in cognitive control deficits. Briefly, we can say that there is not one specific region that plays an important role in schizophrenia, and that there are various brain regions that play a role in it.
References
- Badre, D., 2008. Cognitive control, hierarchy, and the rostro–caudal organization of the frontal lobes. Trends Cogn. Sci. 12 (5), 193–200. http://dx.doi.org/10.1016/j.tics. 2008.02.004.
- Barbalat, G., Chambon, V., Franck, N., Koechlin, E., & Farrer, C. (n.d.). Organization of Cognitive Control Within the Lateral Prefrontal Cortex in Schizophrenia. ARCHIVES OF GENERAL PSYCHIATRY, 66(4), 337-386.
- Dreisbach, G., 2012. Mechanisms of cognitive control: the functional role of task rules. Curr. Dir. Psychol. Sci. 21 (4), 227–231.
- J Daniel eRagland, Charan eRanganath, Joshua ePhillips, Megan Ann Boudewyn, Ann M Kring, Tyler Andrew Lesh, … Cameron S Carter. (2015). Cognitive Control of Episodic Memory in Schizophrenia: Differential Role of Dorsolateral and Ventrolateral
- Prefrontal Cortex. Frontiers in Human Neuroscience, Vol 9 (2015).
- Kayahan B., Ozturk O., Veznedaroglu B., (2004). Cognitive Dysfuntions in Schizophrenia. Retrieved from: http://www.turkiyeklinikleri.com/article/tr-sizofrenide-bilissel-bozukluklar-34836.html.
- Miller, E.K., 2000. The prefrontal cortex and cognitive control. Nat. Rev. Neurosci. 1 (1), 59–65. http://dx.doi.org/10.1038/35036228.
- Miller, E.K., Cohen, J.D., 2001. An integrative theory of prefrontal cortex function. Annu. Rev. Neurosci. 24, 167–202.
Ray, K. L., Lesh, T. A., Howell, A. M., Salo, T. P., Ragland, J. D., - MacDonald, A. W., … Carter, C. S. (2017). Functional network changes and cognitive control in schizophrenia. NeuroImage: Clinical, 15, 161–170.
- Veen, V.V., Carter, C.S., 2006. Conflict and cognitive control in the brain. Curr. Dir.
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