Cognitive function worse in pediatric BD I than II

By Mark Cowen

Children with bipolar I disorder (BD I) have significantly poorer cognitive functioning than those with bipolar II disorder (BD II), research shows.

"These findings move us closer to developing effective cognitive interventions tailored to specific subtypes of pediatric BD patients," comment the researchers.

Writing in the Journal of Child Psychology and Psychiatry, Lindsay Schenkel (Rochester Institute of Technology, New York, USA) and team explain that although a number of previous studies have investigated cognitive profile differences between adult patients with BD I and II, there are no such studies among pediatric patients.

To address this, the team studied 27 children with BD I, 19 with BD II, and 33 age-, gender-, parental socioeconomic status-, and intelligence-matched mentally healthy children who were aged between 8 and 18 years.

All of the participants completed a neurocognitive test battery that comprised the Trail Making Test, the Digit Span subtest from the Weschler Memory Scale-Third Edition, the California Verbal Learning Test-Child Version, the Continuous Performance Test, the Conditional Exclusion Test, the Visual Object Learning Test, the Set Shifting Test, the Controlled Oral Word Association Test, and the Spatial Span Test.

Post hoc analysis revealed that, compared with controls, BD I patients had significantly poorer performance in all domains of cognitive functioning, including attention, executive function, verbal learning and memory, visual memory, and working memory.

BD I patients also had significantly poorer attention, executive function, verbal learning and memory, and visual memory than BD II patients, but there were no differences between the two groups regarding working memory.

BD II patients had significantly poorer verbal learning and memory compared with controls, but no significant differences in other cognitive domains were observed.

Overall, BD II patients had an intermediate pattern of performance on the cognitive tests between BD I patients and controls.

Schenkel et al conclude: "Results from this investigation suggest that neurocognitive deficits are severe and pervasive among BD I pediatric patients relative to BD II patients and healthy controls, and may represent a more cognitively impaired clinical subtype of the disorder.

"Verbal learning and memory deficits were common across both BD I and II subtypes, and may effectively differentiate pediatric BD patients and controls."

They add: "Treatments in BD should target deficits in verbal learning and memory as this may be an important clinical endophenotype for the disorder."

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