A novel scale for measuring mixed states in bipolar disorder.
OBJECTIVE
Conventional descriptions of bipolar disorder tend to treat the mixed state as something of an afterthought. There is no scale that specifically measures the phenomena of the mixed state. This study aimed to test a novel scale for mixed state in a clinical and community population of bipolar patients.


METHODS
The scale included clinically relevant symptoms of both mania and depression in a bivariate scale. Recovered respondents were asked to recall their last manic episode. The scale allowed endorsement of one or more of the manic and depressive symptoms. Internal consistency analyses were carried out using Cronbach alpha. Factor analysis was carried out using a standard Principal Components Analysis followed by Varimax Rotation. A confirmatory factor analytic method was used to validate the scale structure in a representative clinical sample.


RESULTS
The reliability analysis gave a Cronbach alpha value of 0.950, with a range of corrected-item-total-scale correlations from 0.546 (weight change) to 0.830 (mood). The factor analysis revealed a two-factor solution for the manic and depressed items which accounted for 61.2% of the variance in the data. Factor 1 represented physical activity, verbal activity, thought processes and mood. Factor 2 represented eating habits, weight change, passage of time and pain sensitivity.


CONCLUSIONS
This novel scale appears to capture the key features of mixed states. The two-factor solution fits well with previous models of bipolar disorder and concurs with the view that mixed states may be more than the sum of their parts.
Cavanagh
Jonathan
J
University of Glasgow Section of Psychological Medicine, Sackler Institute of Psychobiological Research, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK. jc199d@clinmed.gla.ac.uk
Schwannauer
Matthias
M
Power
Mick
M
Goodwin
Guy M
GM
D000293:Adolescent; D000328:Adult; D000339:Affect; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data*; D011594:Psychometrics / Q000706:statistics & numerical data; D012016:Reference Values; D015203:Reproducibility of Results; D055815:Young Adult