BD II patients exhibit distinct cognitive deficits
MedWire News: Patients with bipolar II disorder (BD II) exhibit cognitive deficits in working and verbal memory, and inhibitory control, results from a review and meta-analysis of published studies suggest.
Writing in the journal Psychological Medicine, Eduard Vieta (University Clinic Hospital of Barcelona, Spain) and team explain: "There is evidence that BD is associated with significant neurocognitive deficits."
However, they add that most studies on neurocognitive deficits in BD have been conducted in BD I patients, with only a few conducted in BD II patients.
To investigate whether BD II patients also show evidence of neurocognitive deficits, and the nature of such deficits, the team searched the literature for relevant studies published between 1980 and 2009.
In total, 15 studies involving nearly 400 adult patients with BD II met criteria for inclusion in the final review.
Most of the studies detected cognitive impairments in BD II patients, the researchers report.
Analysis of the pooled results revealed that, overall, the main cognitive deficits in BD II patients were in working memory and some executive functions, particularly inhibitory control.
Furthermore, around half the studies reported impairments in verbal memory among BD II patients.
However, the team notes that there were significant inconsistencies in the findings, and "methodological differences exist regarding comparative groups, such as heterogeneity of samples or inclusion of different mood states of the illness, for instance, making it difficult to draw conclusions."
Nevertheless, they comment that "though still not clearly established… deficits in BD II subjects were identified mainly in the areas of working memory, inhibitory control, and verbal memory as well."
They add that identifying differences in cognitive abilities between BD II and BD I patients may help in the design of "specific programmes aiming to treat prevailing cognitive dysfunctions for each subtype."
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By Mark Cowen