Comparison of crp and vitamin D levels in patients with schizophrenia and first attack psychosis, healthy siblings of patients and healthy control group in terms of cognitive functions

Introduction and Aim: Schizophrenia is a chronic illness consisting of affective, thought, behavior and cognitive disorders and showing a variety of symptoms and findings. Many hypotheses have been developed on the etiology of the illness. The two of the research subjects that have been emphasized recently are endophenotypic characteristics and inflammatory processes. This study examines the inflammatory processes in schizophrenia etiopathogenesis. Also, first degree relatives of the patients are included in the study. Cognitive disorders, which are partially resistant in the treatment should be focused because they increase social burden of patients and lower functionality. Therefore, the study includes schizophrenia patients, their healthy siblings and healthy groups. The relationship between Vitamin D, which has a important role in growing, developing and differentiating neurons; CRP levels, which is a inflammatory phase reactant and cognitive functions measured by neuropsychological tests. Methods: The participants of the study include the patients having psychotic disorder diagnosis, the individuals whose siblings have schizophrenia diagnosis and healthy individuals. The patient group consists of 36 patients who have not used psychotropic drugs at least for a month, are between 18-60 ages, have been diagnosed as schizophrenia or brief psychotic disorder. On the other hand, the sibling group consists of 31 healthy volunteers whose siblings have been diagnosed as schizophrenia. The control group includes 31 healthy volunteers who do not have any psychiatric illness. The data were collected by WCST, Stroop Test, Trail-making Test, Rey Auditory Verbal Learning Test and Digit Span Test. The tests were administered by the researcher who has been specially trained. Additionally, The CRP and vitamin D levels of the participants were measured to determine the inflammatory levels of the groups. The data were analysed in SPSS 22.0 package program. Findings: When the patient group is compared with sibling group and control group in terms of cognitive functions, psychomotor speed, information processing speed, complex attention functioning with frontal system, focusing attention, working memory, short term memory, long term memory and free recall functions of the patients are disrupted compared to the control group. Also, it is shown that the perseverative tendency of the patients has increased. Impairment is observed in the memory related to retroactive interference of the sibling group compared to the control group in terms of cognitive functions. Another significant difference could not be found in the other areas. There is no significant difference in the levels of vitamin D in the groups. Examining the levels of vitamin D and cognitive functions, the processing speed, information processing and selective attention measured with Stroop Test have a relationship between low vitamin levels. The CRP levels of the patients are higher than the sibling and control group. A relationship between the CRP levels and selective attention, cognitive inhibition ability, processing speed, set change, short term and long term memory functions has been found. Discussion and Conclusion: The findings of the study reveal endophenotypic characteristics of schizophrenia and some significant differences in terms of its relationship with inflammation. Increasing CRP levels may relate to increasing inflammatory processes of the illness. Although they are higher in the patients, the relationship between cognitive disorders diagnosed in the sibling group and inflammatory mechanisms; and their endophenotypic characteristics should be handled in other studies. Keywords: Schizophrenia, endophenotype, siblings, Vitamin D, CRP, inflammation