In our study, based on a sizeable pool of subjects with bipolar disorders and using items drawn from a validated instrument, a nine-factor solution was initially identified with classical factor analysis using a sound methodology for dichotomous items. Our solution accounted for 56.4% of variance of the items, in line with other studies that explored the factor structure of mania (Cassidy et al., 1998a
; González-Pinto et al., 2003
; Serretti et al., 1999
). A subsequent IRT-based factor analysis determined that a model including five of these factors provided a better fit to the data compared to a unidimensional model. The five-factor solution included Psychomotor Activation, Spirituality/Mysticism/Psychoticism, Mixed Irritability, Mixed Instability and Euphoria. To our knowledge, this is the first study investigating factors of mania using an IRT-based approach in a lifetime self-report instrument, such as the MOODS-SR, which captures a broad range of mania/hypomania symptoms, isolated or clustered, temperamental manifestations and atypical features.
The first factor retained using the IRT-based approach, Psychomotor Activation
, includes “core” symptoms of mania, featuring most of the DSM-IV criteria for a manic episode. Of note, five out of nine MOODS-SR items reflecting DSM-IV criteria for manic episode loaded on this factor (see and ). This factor showed a moderate to strong correlation with all the others factors (), suggesting that psychomotor activation is a key element for all the other aspects of mania and hypomania, in line with most of the literature (Murphy and Beigel, 1974
; Double, 1990
; Cassidy et al., 1998a
; Cassidy et al., 2002
; Hantouche et al., 2003
; Benazzi, 2004
; Angst et al., 2005
; Koukopoulos et al., 2005
; Benazzi, 2007b
, Picardi et al., 2007
). Notably, our data showed that increase in energy with reduced sleep (item 136) is an important feature of psychomotor activation. Some authors reported that reduced need for sleep is an independent factor (Cassidy et al., 1998a
; González-Pinto et al., 2003
) and other studies (Serretti et al., 1999
) argue that it is part of psychomotor activation. However, none of these studies has included increase in energy with reduced sleep in the psychomotor activation. In our opinion, the factor Psychomotor Activation
, along with Euphoria
, represent the pure components of mania. In fact, Euphoria
parallels the euphoric-grandiose symptom cluster, described also by Beigel and Murphy (1971)
that brings to mind images of happy, laughing, and flirtatious patients with mania. Notably, item 51 “persistently good or high” is the most frequently reported symptom in our population (87.6%). Since Robertson’s (1890)
description of hilarious mania, this group of symptoms has always been identified with mania (Malhi and Yatham, 2007
) and can be considered a core symptom of pure mania (Benazzi and Akiskal, 2003a
Conversely, Mixed Instability
and Mixed Irritability
delineate the unstable/irritable components of mixed mania (Cassidy et al., 1998b
; Cassidy et al., 2008
). Of note, these attributes consist of trait mood lability that, as suggested by Akiskal (2005)
, are all characteristic of Kretschmer’s description of the cyclothymic temperament (Kretschmer, 1936
). The factor Mixed Instability
includes a number of features that mirror “instability” in mood, work, friendships and personal relationships. Changing sexual partners, unstable mood when using alcohol, frequently changing job, residence, friends or hobbies have been widely described among bipolar patients. In DSM-IV, increased sexual interest is subsumed under the general category of “pleasurable activities” however, this factor goes beyond the concept of “pleasurable activity” emphasizing aspects of instability. Further, our data suggest that all these aspects are closer to the cognitive and neurobiological processes underlying mania rather than being temperamental aspects. The other factor, Mixed Irritability
, features rapid mood changes, hostility and irritability while taking medications other than those prescribed for mood problems and during medical illnesses. The association with the typical mixed component of mania is suggested by item 50 ‘crying and laughing at the same time’. Notably, hostility is one of the most frequently reported symptoms (see , 85.7% of patients). In fact, in our experience, these symptoms may often persist as residual or isolated symptoms.
In our study we did not identify a depressive component because items belonging to depression were not included in the analysis. Moreover, classic mixed states such as anxious mania, excited depression, manic stupor, depression with flight of ideas, inhibited mania or mania with thought poverty could not be identified. However, our data are of relevance because they further support clinical observations on the central role of irritable-unstable mood for the diagnosis of mania using a dimensional lifetime approach. Current classificatory systems (ICD-10 and DSM-IV) place less emphasis on irritable mood which is considered implicitly less important for the establishment of a diagnosis of mania (Cassidy et al., 2008
). Nonetheless, patients with mixed mania need to be promptly recognized and treated and growing evidence suggest that mixed mania is correlated with high rates of psychotic symptoms and hospitalization (Perugi et al., 2001a
) and high suicide risk (Dilsaver et al., 1994
is another factor retained by the IRT-based approach. Religiosity has been rarely investigated, with relevant studies dating back to Carlson and Goodwin (1973)
or Loudon et al. (1977)
. However, it is known that the feeling of well-being, experienced by patients withmania, is often accompanied with a sense of benevolence and a “heightened sense of reality”, as defined by Henderson and Gillespie (1956)
. Of note, this factor includes the item “feelings of being invulnerable” (item 121) that is typical of mood-congruent psychosis. In our opinion, these symptoms cannot be referred only to pure mania or to the mixed mood components of mania, because they bridge a number of different psychopathological states. In fact, these symptoms have been often attributed to clinical entities other than bipolar disorder such as schizoaffective disorder, delusional disorder, substance-induced psychotic disorder and organic psychoses. Further, it is important to emphasize that these symptoms, while apparently belonging to the mixed components of mania, may also occur as residual or isolated symptoms.
Finally, it is important to underline that the IRT-based approach tests the best fitting model and it does not imply that all factors not retained do not belong to the manic spectrumbut, conversely, that they are so highly correlated with the primary dimension that they cannot be identified as separate dimensions. This is further confirmed by the high correlation of the items belonging to these factors with the total score (see ). In fact, creativity, inflated self-esteem, sociability and extraversion have been frequently described in the context of bipolar disorders, representing full blown symptoms, but also an adaptive set of temperamental traits when occurring in moderation (Akiskal et al., 1983
; Akiskal et al., 1998
; Akiskal and Akiskal, 2007
; Goodwin and Jamison, 2007
Several potential limitations of our study need to be acknowledged. One is that 62% of the patients were assessed in the euthymic phase and 38% in the acute phase.While clinical status has a potential impact on the reliability of patients’ report of lifetime signs and symptoms of mania, data from a group of individuals participating in the STEP-BD study who completed the lifetime MOODS-SR questionnaires at baseline and again when their clinical status changed (e.g. from euthymia to depression or from depression to hypomania) indicate that the endorsement of lifetime manic symptoms is stable over time and is not sensitive to changes in clinical status, provided that subjects are not assessed in a full blown and severe manic episode (Fagiolini, in preparation
). Therefore, the fact that participants in our study who were assessed during an acute episode endorsed more items than those assessed in a euthymic state may simply indicate that the former had a more severe form of bipolar disorder.
Another limitation is the use of a database including mood spectrum assessments in English and Italian. While the lack of equivalence of self-report instruments across languages is usually a source of concern in cross-cultural studies, the mood spectrum assessment was developed simultaneously in Italian and English by the bilingual team of the Spectrum Project, which ensured the correspondence of items. A further limitation is that the MOODSSR does not include items related to very severe forms of mania seen in acute inpatient wards and characterized by high levels of excitement, aggressiveness or catatonia. These symptoms, however, are better assessed through direct observation than using a self-report instrument because patients who have experienced these extreme manifestations of mania tend to forget or deny these experiences. Moreover, severe mania is becoming less frequent as a result of the improved diagnostic ability and the availability of drugs preventing its occurrence.
A number of issues warrant consideration in future research. The identification of patients with specific profiles on multiple factors could be used to achieve higher precision in brain imaging or neurobiological studies than is currently achieved using subjects with the same DSM-IV diagnosis. Moreover, it is likely that a better psychopathological characterization of patientsmay inform treatment selection and result in better treatment outcome.