1,721,142 research outputs found
Structural brain correlates of IQ changes in bipolar disorder
No full textBackground. There is increasing evidence that cognitive deficits are present in bipolar disorder
(BP), but their neural correlates have not been fully explored. The aim of this study is to correlate
structural brain abnormalities with cognitive performance in BP and to explore differences between
clinical subtypes.
Method. Thirty-six BP patients (13 men, 23 women) with a mean age of 39 years (range 21–63
years) underwent neuropsychological testing and imaging. Twenty-five patients had bipolar disorder
I (BP I) and 11 had bipolar disorder II (BP II). Patients with co-morbid psychiatric diagnosis,
drug and alcohol abuse or systemic illness were excluded. Correlations between cognitive performance
and structural brain changes were explored using high-resolution anatomical imaging and
magnetization transfer imaging (MTI).
Results. In the whole BP group the difference between estimated pre-morbid IQ and current IQ was
significantly correlated with left-sided reduction of the magnetization transfer ratio (MTR) in the
superior temporal gyrus, uncus and para-hippocampal gyrus. In BP II patients the areas where
these correlations were significant extended to the right superior and middle temporal gyri, cingulate
gyrus, pre-cuneus and adjacent frontal and parietal white matter. The volume of superior
temporal white matter was also correlated with IQ difference in this subgroup.
Conclusions. The study highlights the association between fronto-temporal abnormalities and decline
in IQ in BP. The more extensive abnormalities present in BP II patients suggest that persistent
depression, rather than mania, may be a key pathophysiological factor or that BP II represents a
clinical phenotype with a higher risk of developing cognitive abnormalities
Bipolar I and Bipolar II Disorder: Cognition and Emotion Processing
No full textBACKGROUND:
Cognitive impairment may be part of the endophenotype of bipolar disorder (BP), but little is known about patterns and severity of impairment in BP subgroups and their relation to depression. The same applies to deficits in emotion processing known to be present in BP.
METHOD:
To explore the relationship between depression and impairment in cognition and emotion processing and the differences between BP subgroups, we assessed 36 (25 BP I and 11 BP II) patients using a cognitive battery and a facial emotion recognition task.
RESULTS:
BP patients were impaired compared to published norms on memory, naming and executive measures (Binomial Single Proportion tests, p<0.05). Cognitive performance was largely unrelated to depression ratings. Surprise recognition was the only emotion processing impairment in BP patients compared to controls (patients' recognition score 75% v. controls' 89%, p=0.024). Patients with higher depression ratings were more impaired in recognizing expressions of anger (t23=2.21, p=0.037). BP II patients were more impaired than BP I patients in IQ, memory and executive measures (Mann-Whitney tests, p<0.05). Depression severity or exposure to medication or electroconvulsive therapy (ECT) did not explain these differences.
CONCLUSIONS:
We confirm cognitive impairment and an isolated facial emotion processing deficit in BP patients and suggest that these deficits are largely unrelated to depressive symptoms. Our study also provides evidence that cognitive deficits are more severe and pervasive in BP II patients, suggesting that recurrent depressive episodes, rather than mania, may have a more detrimental and lasting effect on cognition
Memory function after resolution of post traumatic amnesia
No full textPrimary objectives: The aims of this pilot study were (1) to examine neuropsychological, particularly memory functions immediately after post-traumatic amnesia (PTA) resolution according to the Galveston Orientation and Amnesia Test (GOAT), and (2) to provide a preliminary exploration of pattern of performance on GOAT items across PTA duration.
Methods and procedures: Thirty-seven head injured patients were administered the Recognition Memory Tests on the day that PTA resolved. Formal neuropsychological assessment was conducted on average 10 days after PTA resolution.
Main outcomes and results: All the patients in the series showed memory impairment which varied in severity but was typically characterized as global and severe. Deficits in executive and speed and attention functions were common. GOAT items relating to orientation were typically passed, while items concerning anterograde and retrograde recall were most commonly failed across all stages of PTA duration.
Conclusions: These findings suggest that reliance on memory performance as a measure of PTA is not ideal and highlight the need for further research of this issue
Monitoring cognitive changes: psychometric properties of six cognitive tests
No full textObjectives. Repeated neuropsychological assessments are often used to monitor change in cognitive functioning over time. Thus, knowledge about the reliability and stability of neuropsychological tests and the effects of age and IQ is of paramount importance. In this study we document, for six cognitive tests: test-retest reliabilities, practice effects, reliable change (RC) indices corrected for practice, and the impact of premorbid IQ and age.
Design. A sample of 188 normal adults (aged 40-70 years) were administered, on two occasions, one or more of the following tests: the Graded Naming Test (GNT), the Silhouettes Test, two tests of verbal fluency, the Modified Wisconsin Card Sorting Test, and a new test of speed and attention (the Symbol Digit Test). There was a I month interval between assessments. At first assessment, all participants were administered the revised National Adult Reading Test (NART).
Results. The test-retest reliability of the tests ranged from very good (the GNT and Silhouettes Test) to moderate (verbal fluency tests and Symbol Digit Test) and to poor (Modified Card Sorting Test). Significant, although modest, practice effects were found on all tests. RC indices were generally large except for the Graded Naming Test and the Silhouettes Test. Premorbid IQ scores significantly correlated with performance on all the tests, the exception being semantic fluency. Age only correlated with the Silhouettes Test and the new Symbol Digit Test. Neither NART IQ nor age correlated with practice effects.
Conclusion. The psychometric properties of the GNT and Silhouettes Test indicated that they are useful tools for monitoring even small cognitive changes. In contrast, the verbal fluency tests and the new Symbol Digit Test are only suitable for monitoring large changes in performance. The Modified Card Sorting Test is an unreliable tool for monitoring 'executive' functions
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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