Attention Deficits in a Comorbidity-Free Sample of Euthymic Pediatric Bipolar Disorder.

Attention deficits are considered one of the potential endophenotypic markers of Bipolar Disorder (BD). Pediatric bipolar disorder (PBD) likely has stronger genetic underpinnings than adult onset BD; therefore, demonstrating attention deficits in PBD can be both strategic and convincing in attesting their status as one of the potential endophenotypic markers of BD. However, unlike adult literature, uncertainty exists regarding the magnitude of attention deficits in PBD. In this regard, one key unresolved question is the potential impact of attention deficit hyperactivity disorder (ADHD). The main goal of the study was to examine attention deficits in a comorbidity-free sample of euthymic PBD patients. Thirty (21 boys, 9 girls) remitted PBD patients without co-morbidity and thirty age (<17 years), sex, handedness, and Full-Scale IQ matched control subjects were compared on performance on attention tasks. Working memory (WM), which might potentially confound with the attention task performances, was also examined. Compared to controls, PBD patients performed poorly on various tests of attention, but not on any WM tasks. Further, it was found that observed attention deficits were independent of residual mood symptoms, medication effect or illness characteristics. Such attention deficits in this comorbidity-free PBD sample further endorses its status as an endophenotypic marker of bipolar disorders and establishes continuity with deficits found in adult bipolar patients.

Bereitschaftspotential in remitted paediatric bipolar disorder.

Bereitschaftspotential (BP) is an anticipatory slow wave in the brain that typically precedes a voluntary motor act and its deficit reflects abnormal motor preparatory processes in the brain. Although BP deficits have been consistently noticed in schizophrenia, similar research in depression has yielded contradictory results; therefore, it is unclear if motor anticipatory processes are actually abnormal in mood disorder. We compared both early and late BP between thirty remitted paediatric bipolar patients (PBD) and thirty matched healthy control group subjects. We did not find any evidence of BP abnormality in PBD, indicating normal motor preparatory processes in this condition. This finding is in agreement with our previous research reporting normal anticipatory slow waves in bipolar subjects. Future research needs to address the specificity of normal anticipatory slow waves in bipolar disorder, compared to other major Psychoses.

The contingent negative variation in remitted paediatric bipolar patients: no evidence of abnormality.

Although the Contingent Negative Variation (CNV) paradigm has been useful in schizophrenia, limited research involving such paradigm in subjects with Bipolar Disorder (BD) has produced contradictory findings. To the best of our knowledge, no study has investigated CNV in Paediatric Bipolar Disorder (PBD) subjects. Thirty remitted PBD patients and thirty matched healthy control group subjects participated in the study. No significant between group main effect could be found for either CNV latency or amplitude. We propose that CNV is unlikely to be a true endophenotype of BD. However, absence of CNV finding during euthymic phase in BD may help us in advancing our understanding of BD and such finding may, in fact, have some specificity with regard to differentiating BD from schizophrenia.