Gender differences in bipolar I disorder are associated with memory function and may contribute to poor functional outcome particularly in men, UK researchers report.

They found gender by diagnosis interactions in patients with bipolar I disorder were present in immediate memory, both auditory and visual, but not in general intellectual ability, concept formation, and perseveration or response inhibition.

The researchers also note that it is unlikely that their findings “relate to potential differences in illness severity between men and women with bipolar I disorder,” because both patient groups were comparable in terms of age of onset, duration of illness, number of episodes or hospitalizations and global assessment of functioning (GAF) scores.

They evaluated the performances of 86 remitted patients with bipolar I disorder (36 men and 50 women) and 46 mentally healthy individuals (21 men and 25 women) on a series of cognitive tasks.

On the Weschler Memory Scale-III (WMS-III), patients with bipolar I disorder performed significantly worse than mentally healthy controls in immediate visual and auditory memory and auditory delayed memory, but not in visual delayed memory or auditory recognition delayed memory.

When the effects of gender were assessed, women with bipolar I disorder did not perform significantly worse than control women on any of these WMS-III variables, whereas men with bipolar I disorder performed significantly worse than men without the disorder in auditory (average score 96.5 vs 113.2) and visual immediate (92.2 vs 110.7) memory, and marginally worse in auditory delayed memory (92.3 vs 103.3).

Compared with women with bipolar I disorder, men with the condition performed worse in immediate memory (102.4 vs 93.4, respectively) and auditory delayed memory (105.8 vs 92.3), but not significantly so. Immediate memory was significantly correlated with male patients’ overall level of functioning, however, underscoring the importance of memory function in the outcome of bipolar disorder.

Further analysis of the abnormalities in immediate memory test performance, which could reflect either encoding or retrieval, showed that it was retrieval deficits that were greater in men than women with bipolar I disorder.

“This is further supported by the finding of gender differences in delayed auditory memory in bipolar disorder,” say Sophia Frangou, from King’s College London, and colleagues in the journal Psychological Medicine.

They conclude: “Our results support the notion that gender may modulate the degree of immediate memory dysfunction in bipolar disorder and its impact on overall level of function.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

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Bipolar disorder patients experiencing their first acute mania episode present with different illness characteristics and achieve recovery and remission more quickly than patients with multiple episodes, findings from the EMBLEM study show.

First-episode patients were significantly younger, had a lower body mass index, and a higher incidence of past or current cannabis abuse than multiple-episode patients.

First-episode patients also had, on average, significantly higher baseline Young Mania Rating Scale (YMRS) total and Clinical Global Impressions-Bipolar Disorder (CGI-BP) mania scores, compared with multiple-episode patients (28.5 vs 26.3 and 5.0 vs 4.8, respectively).

The researchers note, however, that while first-episode patients had greater illness severity than multiple-episode patients, the latter patients had greater functional impairment, based on self-reports.

They also had higher levels of baseline depressive symptoms than first-episode patients, according to CGI-BP depression and Hamilton Depression Rating Scale total scores.

Mauricio Tohen, from the University of Texas Health Science Center at San Antonio, USA, and colleagues therefore suggest that “the level of functional impairment may not be directly related to the symptomatic severity of the index manic episode but, rather, reflect the extent of prior illness course.”

Of 3115 patients enrolled in the EMBLEM (European Mania in Bipolar Longitudinal Evaluation of Medication) study, 256 presented with a first manic or mixed episode while the remaining patients had previously experienced manic or mixed episodes. All the patients had a CGI-BP mania score of at least 3.

In addition to determining differences in illness characteristics between first- and multiple-episode patients at baseline, the researchers compared the two groups with regard to recovery and remission after 12 weeks of antipsychotic treatment.

A significantly greater percentage of patients in the first-episode group than in the multiple-episode group met the criteria for recovery at the 12-week endpoint (CGI-BP overall score of 2 or below at endpoint), at 39.6% versus 33.1%, respectively. Recovery also occurred more quickly in first-episode than multiple-episode patients.

Significant differences in rates of remission were also seen at the 12-week endpoint, at 80.4% for single-episode patients versus 69.0% for multiple-episode patients, and times to remission were shorter for first-episode patients.

“These findings highlight important distinctions in illness characteristics, outcome and possibly treatment response between patients at different points in the longitudinal course of bipolar disorder,” Tohen et al write in the Journal of Clinical Psychiatry.

They therefore recommend consideration of the longitudinal dimension of bipolar disorder in the determination of prognosis and treatment strategies.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

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Individuals at high risk for hypomania have alterations in sleep and circadian activity similar to those seen in bipolar disorder patients, indicating that such phenomena are not simply an artefact of the illness, conclude UK researchers.

It is common for bipolar disorder patients to experience sleep and circadian rhythm disturbances, which are associated with illness severity and recurrence. However, the premorbid occurrence and significance of such disturbances is not known.

Steven Jones (Lancaster University) and Dave Ankers (South Staffordshire and Shropshire Healthcare NHS Foundation Trust) studied 31 individuals at behavioral risk for hypomania, as measured on the Hypomanic Personality Scale (HPS), and 24 age- and gender-matched healthy controls.

The participants wore an actigraph for 7 days to obtain sleep and circadian activity data, and completed the HPS, the Hypomanic Interpretations Questionnaire (HIQ), the Internal State Scale (ISS), and a sleep diary.

At-risk individuals scored significantly higher than controls on the HIQ, with the results indicating that not only did at-risk participants make more positive self-referent appraisals for hypomania-relevant experiences than controls, but alsohad more of those experiences.

The team also found that at-risk individuals had a significantly reduced relative amplitude of activity cycle than controls, at 0.81 versus 0.86, suggesting that there was a smaller difference between the most active and least active periods in a day.

Hypomania-risk participants had a significantly shorter sleep duration than controls, at 6:53 versus 7:28 h:m, as well as significantly more variable sleep duration, fragmentation of sleep, and sleep efficiency. They also reported significantly later bedtimes than controls, at 1:20 versus 0:16 h:m.

The team writes in the Journal of Clinical Psychology: “This study found some evidence that circadian markers do differ in those putatively at risk for bipolar disorder when compared with controls.

“This may indicate that circadian differences exist prior to illness onset and could, therefore, represent a core vulnerability for the disorder.”

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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