Bipolar I disorder patients with a predominant manic/hypomanic polarity (MP) are similar in temperament to those with a predominant depressive polarity (DP), but differ from patients with unipolar major depression (UP), research shows.

Writing in the Journal of Affective Disorders, Eduard Vieta (University of Barcelona, Spain) and team explain: “Recently, the concept of predominant polarity… has been introduced to further characterize subtypes of bipolar disorders.”

They add: “This concept has been proven to have diagnostic and therapeutic implications, but little is known on the underlying psychopathology and temperaments.“

To validate the concept of predominant polarity and investigate the relationship with temperament, the team studied 124 patients with bipolar I disorder and 19 with UP.

The bipolar patients were assessed for predominant polarity, with DP defined as at least two thirds of past episodes fulfilling the DSM-IV criteria for major depressive episode, and MP defined as at least two thirds of past episodes fulfilling DSM-IV criteria for manic or hypomanic episodes.

All the participants underwent temperament assessments using the Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego Auto questionnaire (TEMPS-A). Temperament was assessed when patients were in full remission according to the DSM-IV criteria (no significant signs or symptoms of the disorder during the past 2 months).

The team found that 55% of the bipolar disorder patients met criteria for predominant polarity, with 47 classified as MP and 22 as DP.

Age at onset was lower in both the MP and DP bipolar groups compared with the UP group. Unipolar patients showed a longer duration of depression compared with both the MP and DP bipolar groups, but there were no significant differences in the number of suicide attempts between the groups.

Regarding temperament assessments, the mean TEMPS-A scores on the hyperthymic and cyclothymic subscales were higher in MP and DP patients compared with UP patients, while the UP group scored significantly higher than both MP and DP bipolar groups on the depressive temperament scores.

Anxious temperament scores were statistically higher in the UP group than the MP group, but did not differ between DP and UP groups. Irritable temperament scores did not differ among the three groups.

Overall, there were no significant differences in temperament profiles between the MP and DP bipolar groups.

Vieta et al conclude: “Our results show that both bipolar I MP and DP subgroups are temperamentally similar and different from UP. Depression in DP bipolar I patients should be viewed as the overlap of depression on a hyperthymic/cyclothymic temperament.”

They add: “These findings confirm the value of the predominant polarity concept as well as the importance of temperaments to separate bipolar from unipolar disorders.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a part of Springer Science+Business Media. © Current Medicine Group Ltd; 2009

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UK researchers have found that individuals with bipolar disorder (BD) respond differently to positive mood induction than healthy individuals.

They hope that knowing how patients with bipolar disorder respond to positive mood induction could enable clinicians to help BD patients better regulate their mood. Guidance during cognitive behavioral therapy could teach patients to become aware of the automatic changes to emotional processing that occur during the early stages of mood elevation.

In the present study, Anne Farmer (Institute of Psychiatry, London) and co-authors investigated the effect of positive mood induction on emotional processing in 15 euthymic individuals with BD and 19 gender- and age-matched healthy controls, using the Affective Go/No-go test (AGNG) and the Cambridge Gamble task (CGT).

The researchers manipulated mood using a feedback paradigm, which was found to be more effective than more widely used techniques. Mood induction using the “Go” task significantly elevated mood in both groups, and this effect lasted until after completion of the AGNG and CGT.

Patients in the BD group responded more slowly on the CGT when presented with more difficult decisions (when the probability of being correct was lower) than controls, and this effect remained significant after adjusting for age. However, no differences were seen between groups in the extent to which participants altered their betting behavior as a function of risk, or in the quality of decision making.

The authors say that the slow responses made in the face of a difficult decision reflect the BD patients’ “difficulty in overcoming the inclination to engage in behavior with a high potential for negative consequences, which may have been elicited by the mood induction.”

Furthermore, bipolar patients showed a positive emotional bias on the AGNG, as they made significantly more inappropriate responses to positive distractor words than negative distractor words following mood induction, whereas controls did not.

“These data suggest that individuals with BD and healthy controls respond to positive mood induction in a qualitatively different manner,” write the authors in the journal Psychological Medicine.

Farmer et al say that positive mood induction in euthymic individuals with BD “is sufficient to re-establish the biases in information processing and disruptions to decision-making behavior that occur in the manic state.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a part of Springer Science+Business Media. © Current Medicine Group Ltd; 2009

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