By Lucy Piper, Senior medwireNews Reporter
Researchers have identified a six-factor latent structure that they say best describes the symptomatology of hospitalized patients with bipolar mania.
Their exploratory factor analysis (EFA) of data obtained from 117 manic inpatients who completed the Schedule for Affective Disorders and Schizophrenia revealed a six-factor solution that included depression, suicide, insomnia, mania, psychosis and anxiety.
The solution was confirmed in a confirmatory factor analysis that looked at the current data alongside three other models by Johnson et al, Swann et al and Rogers et al.
A six-factor solution is in agreement with the model of Swann et al, but the researchers, led by Alberto Filgueiras (Pontifícia Universidade Católica do Rio De Janeiro, Brazil), note that the dimensions of the current model were very different and more similar to the structure proposed by Rogers et al, which consists of just four factors.
Indeed, the anxiety/anxious pessimism and psychosis were the only dimensions in the current solution that overlapped with the model of Swann et al.
Unlike psychosis, anxiety is not considered typical for patients with mania, so the researchers postulate that manic patients may either experience implicit anxiety caused by the manic episode itself or some patients feel anxious due to a confinement state during a manic episode.
They say that both hypotheses are plausible and that further research is needed to determine the role of anxiety in mania.
The current EFA solution included mania, depression and psychosis, which was in agreement with the models of Johnson et al and Rogers et al, and like the Rogers et al model also included insomnia symptoms.
These are not unusual in manic patients, but the researchers question why insomnia did not load in the manic factor. They suggest that manic patients may experience insomnia differently; some may feel they are not sleeping well, but it does not matter to them, or they are unaware of their own insomnia. Alternatively, insomnia could be associated with the severity of bipolar disorder.
The current EFA solution also identified suicide as a specific dimension. “This was an unexpected result because suicidal symptoms tend to appear among depressive symptoms,” writes the team in European Psychiatry.
They propose that manic patients might show suicidal tendencies due to aggressive behaviour, impulsivity rejection or pain, as well as depression.
The researchers were unable to find a parsimonious model to explain the variance in symptoms during mania, but suggest that symptoms may be too diverse to be explained in four or five factors.
“The model of Swann et al […] showed the same number of dimensions as the EFA in the present study,” they point out. “This probably means that mania is more complex and presents more groups of symptoms than schizophrenia –which normally shows three dimensions.”
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