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Factor Analysis of Mania

Factor Analysis of Mania Manic episodes, which are mandatory for the diagnosis of bipolar disorder, are traditionally viewed as "mood episodes."1 It has been proposed that variables related to activation level, and not to mood state, constitute the core characteristics of the manic syndrome.2 As exact phenotype characterization is crucial for the identification of biological and genetic markers, the available diagnoses systems may be insufficient. In a recent article Cassidy et al3 describe the symptom structure of mania identifying dysphoria, psychomotor acceleration, psychosis, increased hedonic function, and irritable aggression as separate factors in a sample of 237 bipolar subjects. They point out the substantial lack of empirical studies supporting the psychopathological definition of manic states.4,5 Therefore, a replication on a large sample is needed. We collected data from 523 white subjects (females/males=341/182; mean (±SD) age=45.134 ± 13.99 years; mean (±SD) onset=29.92±23.80 years) consecutively admitted to the Mood Disorder Center of San Raffaele Hospital, Milan, Italy (n=437), and Department of Psychiatry, University of Bonn, Bonn, Germany (n=86), after informed consent to participate was obtained. The patients were diagnosed as affected by bipolar disorder type I according to DSM III-R criteria and assessed using the Operational Criteria Checklist for Psychotic Illness (OPCRIT6). While Cassidy et al3 assessed the symptoms of a single episode of the disorder, which can change during a lifetime, we documented with the OPCRIT the presence or absence of symptoms ever occurring during lifetime, making it most valuable for genetic studies that search for trait-markers rather than state-markers. Principal component factor analysis with Varimax rotation was performed on 509 subjects, 14 subjects were excluded due to missing items. Eigenvalues greater than 1 and Scree plot inspection were used for the selection of the number of factors. Further details of the method are reported in our previous analysis performed on a mixed psychotic population.7 In that analysis we studied a pool of subjects affected by schizophrenia, delusional disorder, and mood disorders. This analysis was performed on a larger sample of bipolar subjects (292 subjects were included in the previous analysis) and including only manic symptoms. A 3-factor solution was obtained and it explained 52.4% of the rotated variance (Table 1). The first factor explains the largest part of the variance and it is composed of psychic and motor excitement items. Psychosis items compose the second factor; irritability items the third factor. Factor composition was the same when including only Italian subjects. The score distribution for the excitement factor is highly left skewed, this means that, as expected, most subjects presented at least some excitement symptoms. On the contrary, the psychosis factor is skewed to the right, underscoring the clinical observation that only a minority of subjects present psychotic features during affective episodes.8 The irritability factor was the only one with a normal distribution (Kolmogorov-Smirnov test), suggesting that irritability is a common feature among manic episodes. View LargeDownload Factor Loadings of Manic Symptoms* Our results are somewhat different from the ones reported by Cassidy et al.3 We scored symptoms using a lifetime perspective, and this prevented us from including depressive items. Therefore we analyzed "pure" mania without including depressive symptoms. Our first factor includes "core items" of mania, this factor has been previously identified4 and it constitutes factors 2 and 4 of the cited study.3 Except for depressive items, all factors represent an independent confirmation of the original analysis.3 Our excitement factor is overlapping with factors 2 through 4, our psychosis factor with factor 3 and our irritability factor with factor 5. In conclusion, our data strongly support the presence of excitement, psychosis, and irritability factors in manic states. Corresponding author: Alessandro Serretti, MD, Department of Neuropsychiatric Sciences, Ospedale San Raffaele, University of Milan School of Medicine, Via Luigi Prinetti 29, 20127 Milan, Italy (e-mail: serretti.alessandro@hsr.it). References 1. Bauer MSCrits-Christoph PBall WADewees EMcAllister TAlahi PCacciola JWhybrow PC Independent assessment of manic and depressive symptoms by self-rating: scale characteristics and implications for the study of mania. Arch Gen Psychiatry. 1991;48807- 812Google ScholarCrossref 2. American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition. Washington, DC American Psychiatric Association1987; 3. Cassidy FForest KMurry ECarroll BJ A factor analysis of the signs and symptoms of mania. Arch Gen Psychiatry. 1998;5527- 32Google ScholarCrossref 4. Beigel AMurphy D Assessing clinical characteristics of the manic state. Am J Psychiatry. 1971;128688- 694Google Scholar 5. Double D The factor structure of manic rating scales. J Affect Disord. 1990;18113- 119Google ScholarCrossref 6. McGuffin PFarmer AHarvey I A polydiagnostic application of operational criteria in studies of psychotic illness: development and reliability of the OPCRIT system. Arch Gen Psychiatry. 1991;48764- 770Google ScholarCrossref 7. Serretti AMacciardi FSmeraldi E Identification of symptomatologic patterns common to major psychoses: proposal for a phenotype definition. Am J Med Gen. 1996;67393- 400Google ScholarCrossref 8. Johnson JHorwath EWeissman MM The validity of major depression with psychotic features based on a community study. Arch Gen Psychiatry. 1991;481075- 1081Google ScholarCrossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of General Psychiatry American Medical Association

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Publisher
American Medical Association
Copyright
Copyright © 1999 American Medical Association. All Rights Reserved.
ISSN
0003-990X
eISSN
1598-3636
DOI
10.1001/archpsyc.56.7.671
Publisher site
See Article on Publisher Site

Abstract

Manic episodes, which are mandatory for the diagnosis of bipolar disorder, are traditionally viewed as "mood episodes."1 It has been proposed that variables related to activation level, and not to mood state, constitute the core characteristics of the manic syndrome.2 As exact phenotype characterization is crucial for the identification of biological and genetic markers, the available diagnoses systems may be insufficient. In a recent article Cassidy et al3 describe the symptom structure of mania identifying dysphoria, psychomotor acceleration, psychosis, increased hedonic function, and irritable aggression as separate factors in a sample of 237 bipolar subjects. They point out the substantial lack of empirical studies supporting the psychopathological definition of manic states.4,5 Therefore, a replication on a large sample is needed. We collected data from 523 white subjects (females/males=341/182; mean (±SD) age=45.134 ± 13.99 years; mean (±SD) onset=29.92±23.80 years) consecutively admitted to the Mood Disorder Center of San Raffaele Hospital, Milan, Italy (n=437), and Department of Psychiatry, University of Bonn, Bonn, Germany (n=86), after informed consent to participate was obtained. The patients were diagnosed as affected by bipolar disorder type I according to DSM III-R criteria and assessed using the Operational Criteria Checklist for Psychotic Illness (OPCRIT6). While Cassidy et al3 assessed the symptoms of a single episode of the disorder, which can change during a lifetime, we documented with the OPCRIT the presence or absence of symptoms ever occurring during lifetime, making it most valuable for genetic studies that search for trait-markers rather than state-markers. Principal component factor analysis with Varimax rotation was performed on 509 subjects, 14 subjects were excluded due to missing items. Eigenvalues greater than 1 and Scree plot inspection were used for the selection of the number of factors. Further details of the method are reported in our previous analysis performed on a mixed psychotic population.7 In that analysis we studied a pool of subjects affected by schizophrenia, delusional disorder, and mood disorders. This analysis was performed on a larger sample of bipolar subjects (292 subjects were included in the previous analysis) and including only manic symptoms. A 3-factor solution was obtained and it explained 52.4% of the rotated variance (Table 1). The first factor explains the largest part of the variance and it is composed of psychic and motor excitement items. Psychosis items compose the second factor; irritability items the third factor. Factor composition was the same when including only Italian subjects. The score distribution for the excitement factor is highly left skewed, this means that, as expected, most subjects presented at least some excitement symptoms. On the contrary, the psychosis factor is skewed to the right, underscoring the clinical observation that only a minority of subjects present psychotic features during affective episodes.8 The irritability factor was the only one with a normal distribution (Kolmogorov-Smirnov test), suggesting that irritability is a common feature among manic episodes. View LargeDownload Factor Loadings of Manic Symptoms* Our results are somewhat different from the ones reported by Cassidy et al.3 We scored symptoms using a lifetime perspective, and this prevented us from including depressive items. Therefore we analyzed "pure" mania without including depressive symptoms. Our first factor includes "core items" of mania, this factor has been previously identified4 and it constitutes factors 2 and 4 of the cited study.3 Except for depressive items, all factors represent an independent confirmation of the original analysis.3 Our excitement factor is overlapping with factors 2 through 4, our psychosis factor with factor 3 and our irritability factor with factor 5. In conclusion, our data strongly support the presence of excitement, psychosis, and irritability factors in manic states. Corresponding author: Alessandro Serretti, MD, Department of Neuropsychiatric Sciences, Ospedale San Raffaele, University of Milan School of Medicine, Via Luigi Prinetti 29, 20127 Milan, Italy (e-mail: serretti.alessandro@hsr.it). References 1. Bauer MSCrits-Christoph PBall WADewees EMcAllister TAlahi PCacciola JWhybrow PC Independent assessment of manic and depressive symptoms by self-rating: scale characteristics and implications for the study of mania. Arch Gen Psychiatry. 1991;48807- 812Google ScholarCrossref 2. American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition. Washington, DC American Psychiatric Association1987; 3. Cassidy FForest KMurry ECarroll BJ A factor analysis of the signs and symptoms of mania. Arch Gen Psychiatry. 1998;5527- 32Google ScholarCrossref 4. Beigel AMurphy D Assessing clinical characteristics of the manic state. Am J Psychiatry. 1971;128688- 694Google Scholar 5. Double D The factor structure of manic rating scales. J Affect Disord. 1990;18113- 119Google ScholarCrossref 6. McGuffin PFarmer AHarvey I A polydiagnostic application of operational criteria in studies of psychotic illness: development and reliability of the OPCRIT system. Arch Gen Psychiatry. 1991;48764- 770Google ScholarCrossref 7. Serretti AMacciardi FSmeraldi E Identification of symptomatologic patterns common to major psychoses: proposal for a phenotype definition. Am J Med Gen. 1996;67393- 400Google ScholarCrossref 8. Johnson JHorwath EWeissman MM The validity of major depression with psychotic features based on a community study. Arch Gen Psychiatry. 1991;481075- 1081Google ScholarCrossref

Journal

Archives of General PsychiatryAmerican Medical Association

Published: Jul 1, 1999

References

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