Spesifity and sensitivity of neurocognitive tests in bipolar disorder: A comparative study

AIM: Bipolar disorder is one of the important mental illnesses affecting daily life, characterized with its repetitive, manic ve depressive episodes and well being periods named, euthymia. While until recently, no proved relationship has been shown between neurophyschologic methods, as result of the developments afterwards, neuropsychologic tests that could give an idea about the localization area of the illnesses have found their place at researches and applications. It has been known long before that cognitive breakdown could take place at bipolar disorders, especially in the last years, there has been an increasing number of studies at this subject.At various studies, it has been repetitively found out that significant performance deficit especially with verbal learning, memory and extended attention functions have been observed at bipolar patients. Comparative studies are being conducted especially with schizophrenia patients and neuro-cognitive deficits at schizophrenia patients and neuro-cognitive deficits at bipolar patients are being compared. Especially at the last years, This situation also includes hope towards finding distinctive test battery or test(s) in the neurocognitive tests proposed for application at schizophrenia and bipolar disorders.The aim of this study could be summarized as to detect specificity and sensitivity of neuropsychologic tests at bipolar disorder, thereby light the way towards detection of cognitive functioning deficits at diagnosis or treatment strategies possible at future with the help of specified tests and by detecting specified tests, provide a practical aspect which could be applied at the treatment and followup periods of all bipolar patients in future.METHOD: The research population consists of patients who have applied to Psycosis and Bipolar Disorder Policlinic at Celal bayar University in 1 year and whose illness are in remission. The sample is 50 psycosis and 51 bipolar patients whi applied to this policlinic and a control group of 50 people who are sociodemographically suitable to these patients. The inclusion kriteria are; age between 18-65, minimum primary school graduate, no detected medical neurologic disorder, for schizophrenia patients being in remission according to Andreasen criteria, for bipolar patients complying remission criteria according to Young mania and Hamilton mood evaluation scales. A SCID-I (SCID-CV) meeting has been made with the patients and control group included in the research and the patients have been diagnosed according to DSM-IV. A sociodemographic data form was given to the patients with detected Bipolar Disorder as a result of these meetings and Hamilton Depression Evaluation and Young Mania Evaluation scales have been applied to these patients and compliance with the inclusion criteria have been checked. Patients with Schizophrenia diagnosis have been checked according to PANNS items P1 (Delusion), P2 (Distraction), P3 (Hallucination), G5 (Manerism and Body Posture), G9 (Unusual Thought Content), N1 (Emotion Blunting), N4 (Passive, Freewillingly alienation from society), N6 (Loss of natural fluency in speaking) and remission evaluation according to Andreasen criteria have been conducted. A control group with similar sociodemographic characteristics has been determined for the patients who are suitable to be included in the study. SCID-I meeting has been made with control group and pyschiatric illnesses have been excluded. Afterwards, IQ evaluation for patients and control group have been conducted according to Wechsler Memory Scale, Serial Digit Learning Test, Stroop Test, Cancellation Test, Judgement of Line Orientation Test, Wisconsin Card Sorting Test, Iowa Gambling Test, Continuous Performance Test, Trail Making Test, Rey Audotoryl and Verbal Learning Test, Facial Emotion Identification Test, Facial Emotion Discrimination Test have been applied. Test results have been evaluated according to the corrected IQ levels.At the statistical evaluation, chi-square test for the rational values and t test for numeric values have been applied in order to detect differences in the sociodemographic data of the groups. For the evaluation of test performances and detection of siginificance levels between groups ANOVA, for the evaluation of significance levels Tukey post-hoc analysis have been applied. For the evaluation of the tests by equalization of IQ scores ANCOVA, for the evaluation of specificity-sensitivity levels of the tests ROC (Receiver operating characteristic curves) curves have been used.RESULTS: Considering patient groups and control group sociodemographically, no statistical difference between the groups in terms of gender, education period, financial condition, illness period ve number of hospitalization have been detected. It has been observed that the statistical difference (p=0,027) originated from age characteristics of the groups was due to the younger age average of schizophrenia patients (35,8±11,37) compared to that of bipolar patients (40,86±11,50) and control group (39,86±11,20). Significant statistical difference has been found in the category of occupation (p=0,019). The reason for this statistical significance has been thought of being due to high rate of unemployed in the schizophrenia patients. Also a statistically significant difference (p=0,009) has been found between patient and control groups, when compared in terms of state of occupation.While 56,9% of bipolar patients and 64% of the control group were married, the percentage at schizophrenia patients have been found to be 30% and this difference was considered to be statistically significant. There has been no statistically significant difference found between bipolar and schizophrenia patients in terms of presence of additional physical illness.When neuro-cognitive performances are evaluated and total scores calculated from Wechsler Memory Scale are considered, the IQ levels of schizophrenia patients have been found to be lower than those of bipolar patients and healthy control group, IQ levels of bipolar patients were also found to be lower than those of the control group. Among the applied tests used in this study, Serial Digit Learning Test, Stroop Test, Wisconsin Card Sorting Test number of completed categories, Continuous Performance Test, Trail Making Test, Rey Audotory and Verbal Learning Test showed worse results for bipolar patients compared with the control group and Rey Audotory and Verbal Learning Test and IQ points showed better results for bipolar patients when compared to schizophrenia patients and at the other tests, bipolar patients showed similar performance to that of schizophrenia patients. When ROC analyses were applied in order to evaluate specificity, values below the curve were not found to be sufficient enough to distinct the illnesses.CONCLUSION: When the results of the study and available literature have been evaluated together, it could stated that neuropyschologic evaluation has become a must for the bipolar disorder and careful attention has to be given during medication choice, establishment of occupational and social functioning and prognosis tracking. It is among our suggestions that if the neuropsychologic tests become a general-use tool for bipolar disorder, the patient could be evaluated biopyschosocially from an extended perspective and among these tests, especially those measuring verbal learning, memory and extended attention should be be priorly used in general practice. Considering the tests applied in our study, use of Wechsler Memory Scale, Serial Digit Learning Test, Stroop Test, Continuous Performance Test, Rey Audotory and Verbal Learning Test could be recommended. Widespread use of these tests could lead considering the future developments in this field more importantly and it could provide a different perspective towards research and development studies of medication in future. In the future, treatments that act to neuro-cognitive functions positively could become a part of routine treatment programs or application of psychotherapies in this field could be brought into agenda of the practice.