Cognitive deficits do not indicate oncoming manic episode
medwireNews: Neurocognitive deficits among those who are at ultra high risk (UHR) for psychosis do not significantly differ between those who transition to bipolar disorder (UHR-BD) and those who do not transition to bipolar disorder or psychosis (UHR-NT), a study finds.
"The lack of difference between UHR-BD and UHR-N[T] suggests there may be no neurocognitive impairment specific to BD at an early stage of illness," write Aswin Ratheesh (Orygen Youth Health, Melbourne, Australia) and colleagues. "This is in line with findings of preserved neurocognition in childhood or adolescence prior to the onset of BD."
However, the authors note in the Journal of Affective Disorders, UHR-BD participants performed poorly with regard to IQ, abstract visual reasoning, and visuomotor speed and attention, when compared with mentally healthy individuals.
Cognitive deficits are well known to occur in individuals with BD after their first manic episode. To explore whether such deficits occur prior to an initial manic episode, Ratheesh and co-authors followed up a cohort of 416 young people (aged 15-30 years) between 4 and 13 years after they were recruited for the study.
While never having had a previous psychotic episode, the participants were identified as being UHR for psychosis according to a Comprehensive Assessment of At-Risk Mental States rating.
Over a mean follow-up period of 8.2 years, 16 participants developed BD. When compared with 66 age- and gender-matched controls, these patients had lower performance scores in picture completion, Trail-Making Tests, and global intelligence.
While the UHR-BD group had lower global functioning at baseline compared with 46 UHR-NT patients, baseline demographic and neurocognitive characteristics did not significantly differ.
Interestingly, the UHR-NT group and healthy controls had similar performances on the picture completion and visuomotor speed and attention tests. "This is suggestive of a specific decrement in the BD group prior to the onset of first episode of mania," the authors speculate.
But the overall findings "may reflect a lack of statistical power or that it may be difficult to distinguish those that will develop BD by their clinical profile," notes the team.
"Together, it may be that certain neurocognitive decrements are markers of at risk for later BD. However, given some inconsistency between tasks tapping similar functions and the size of the sample, this requires further examination."
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By Peter Sergo, medwireNews Reporter