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

Contingent negative variation in patients with deficit schizophrenia or bipolar I disorder with psychotic features: measurement and correlation with clinical characteristics

BACKGROUND

Schizophrenia is a highly heterogeneous disease. Event-related potentials have been regarded to establish intermediate phenotypes of schizophrenia. Our previous study found that patients with deficit schizophrenia (DS) are relatively homogeneous and show a significantly longer onset latency of contingent negative variation (CNV) expectancy wave.

AIMS

To further examine CNV in patients with first-episode and drug-naïve DS or bipolar I disorder (BP I) with psychotic features, and also investigate correlations between CNV and clinical characteristics in DS and BP I.

METHOD

We elicited a CNV using an alarm (S1)-imperative (S2) paradigm in 30 DS patients or 33 BP I with psychotic features as well as 40 healthy controls.

RESULTS

CNV amplitude was significantly smaller and reaction time significantly longer in the DS and BP I groups than in healthy controls. Post-imperative negative variation (PINV) interval was significantly shorter in the DS group than in healthy controls. The onset latency of CNV expectancy wave was significantly longer and PINV area significantly smaller in the DS group than in the other groups. In the DS group, CNV amplitude and PINV interval correlated negatively with the subscale of negative symptoms on the Positive and Negative Syndrome Scale (PANSS); CNV amplitude also correlated negatively with disease duration. In the BP I group, CNV amplitude and reaction time showed no correlation with clinical features.

CONCLUSIONS

CNV amplitude is a common trait marker for psychosis. The onset latency of CNV expectancy wave appears to be a specific trait marker and may be used to identify candidate genes for DS.

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.