The neurocognitive functioning in bipolar disorder: a systematic review of data

Annals of General Psychiatry, Dec 2015

Background During the last decades, there have been many different opinions concerning the neurocognitive function in Bipolar disorder (BD). The aim of the current study was to perform a systematic review of the literature and to synthesize the data in a comprehensive picture of the neurocognitive dysfunction in BD. Methods Papers were located with searches in PubMed/MEDLINE, through June 1st 2015. The review followed a modified version of the recommendations of the Preferred Items for Reporting of Systematic Reviews and Meta-Analyses statement. Results The initial search returned 110,403 papers. After the deletion of duplicates, 11,771 papers remained for further evaluation. Eventually, 250 were included in the analysis. Conclusion The current review supports the presence of a neurocognitive deficit in BD, in almost all neurocognitive domains. This deficit is qualitative similar to that observed in schizophrenia but it is less severe. There are no differences between BD subtypes. Its origin is unclear. It seems it is an enduring component and represents a core primary characteristic of the illness, rather than being secondary to the mood state or medication. This core deficit is confounded (either increased or attenuated) by the disease phase, specific personal characteristics of the patients (age, gender, education, etc.), current symptomatology and its treatment (especially psychotic features) and long-term course and long-term exposure to medication, psychiatric and somatic comorbidity and alcohol and/or substance abuse.

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The neurocognitive functioning in bipolar disorder: a systematic review of data

Tsitsipa and Fountoulakis Ann Gen Psychiatry The neurocognitive functioning in bipolar disorder: a systematic review of data Eirini Tsitsipa 2 Konstantinos N. Fountoulakis 0 1 0 Division of Neurosciences, 3rd Department of Psychiatry, School of Medicine, Aristotle University of Thessaloniki , 6, Odysseos street (1st Parodos, Ampelonon str.) 55536 Pournari Pylaia, Thessaloniki , Greece 1 Division of Neu- rosciences, 3rd Department of Psychiatry, School of Medicine, Aristotle Uni- versity of Thessaloniki , 6, Odysseos street (1st Parodos, Ampelonon str.) 55536 Pournari Pylaia, Thessaloniki , Greece 2 Aristotle University of Thessaloniki , Thessaloniki , Greece Background: During the last decades, there have been many different opinions concerning the neurocognitive function in Bipolar disorder (BD). The aim of the current study was to perform a systematic review of the literature and to synthesize the data in a comprehensive picture of the neurocognitive dysfunction in BD. Methods: Papers were located with searches in PubMed/MEDLINE, through June 1st 2015. The review followed a modified version of the recommendations of the Preferred Items for Reporting of Systematic Reviews and MetaAnalyses statement. Results: The initial search returned 110,403 papers. After the deletion of duplicates, 11,771 papers remained for further evaluation. Eventually, 250 were included in the analysis. Conclusion: The current review supports the presence of a neurocognitive deficit in BD, in almost all neurocognitive domains. This deficit is qualitative similar to that observed in schizophrenia but it is less severe. There are no differences between BD subtypes. Its origin is unclear. It seems it is an enduring component and represents a core primary characteristic of the illness, rather than being secondary to the mood state or medication. This core deficit is confounded (either increased or attenuated) by the disease phase, specific personal characteristics of the patients (age, gender, education, etc.), current symptomatology and its treatment (especially psychotic features) and long-term course and long-term exposure to medication, psychiatric and somatic comorbidity and alcohol and/or substance abuse. Background The neurocognitive dysfunction in BD has been the focus of debate for many years. It was not clear whether the observed neurocognitive deficit could be explained by iatrogenic or alcohol and/or drug abuse effects or by the temporary functional changes which constitute the result of mood changes. Also, it was unclear whether the impairment is the product of degenerative structural brain changes or of some kind of structural changes of a neurodevelopmental origin (trait), or it is secondary to mood dysregulation (state). Recent data suggested that the neurocognitive deficit is not only an enduring component of the illness, but also represents a core primary characteristic of the illness, rather than being secondary to the mood state or medication [ 1 ]. It has been suggested by recent data that 84 % of patients suffering from schizophrenia, 58.3  % of psychotic major depressive patients, and 57.7 % of psychotic BD patients are neurocognitively impaired (at least one SD below healthy controls in at least two domains) [ 2 ]. It has also been suggested that patients with BD are more creative (e.g., artists, scientists, etc.) and have higher IQ in comparison to the general population [ 3–7 ]. However, more recent data reported a significant and broad neurocognitive deficit, which seems to be present even before the first manifestation of mood symptoms, and it persists across the different phases and even worsens during the course of the illness [ 8–13 ]. Several studies suggest that 40 % of BD patients are impaired in one neurocognitive domain, one-third or more are impaired in at least two neurocognitive domains and 22 % in three or more domains [ 14, 15 ]. This deficit is rather stable and relatively independent from mood changes, probably reflecting trait features of BD [ 16–19 ] Even after controlling for confounding variables, such as education and social class and clinical symptoms, it has been indicated that the neurocognitive impairment in BD is less pronounced in comparison to that in schizophrenia [ 20, 21 ]. Gender, age, education, phase of the illness and medication status constitute some of the identified confounding factors. Additionally, patients in a severe depression or mania cannot be tested. A significant limitation in this kind of research is that the performance in most tests is influenced by more than one neurocognitive process. It is a fact that the boundaries between neurocognitive processes are unclear and no process is completely independent from the others. Different approaches in their classification and nomenclature have been proposed, adding to the confusion. The domain of executive functions, particularly, is open to several different approaches and conceptualizations. Th (...truncated)


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Eirini Tsitsipa, Konstantinos Fountoulakis. The neurocognitive functioning in bipolar disorder: a systematic review of data, Annals of General Psychiatry, 2015, pp. 42, 14, DOI: 10.1186/s12991-015-0081-z