The authors of this paper do not have any commercial associations that might pose a conflict of interest in connection with this manuscript.
The genetic and environmental influences of event-related gamma oscillations on bipolar disorder
Article first published online: 15 JUN 2011
© 2011 John Wiley and Sons A/S
Volume 13, Issue 3, pages 260–271, May 2011
How to Cite
Hall, M.-H., Spencer, K. M., Schulze, K., McDonald, C., Kalidindi, S., Kravariti, E., Kane, F., Murray, R. M., Bramon, E., Sham, P. and Rijsdijk, F. (2011), The genetic and environmental influences of event-related gamma oscillations on bipolar disorder. Bipolar Disorders, 13: 260–271. doi: 10.1111/j.1399-5618.2011.00925.x
- Issue published online: 15 JUN 2011
- Article first published online: 15 JUN 2011
- Received 26 August 2010, revised and accepted for publication 5 February 2011
- bipolar disorder;
- gamma oscillation;
Hall M-H, Spencer KM, Schulze K, McDonald C, Kalidindi S, Kravariti E, Kane F, Murray RM, Bramon E, Sham P, Rijsdijk F. The genetic and environmental influences of event-related gamma oscillations on bipolar disorder. Bipolar Disord 2011: 13: 260–271. © 2011 The Authors. Journal compilation © 2011 John Wiley & Sons A/S.
Objectives: Gamma oscillations have been proposed to play an important role in neural information coding. There have been a limited number of electrophysiology studies in evoked gamma band responses (GBRs) in bipolar disorder (BPD). It is also unclear whether GBR deficits, if present, are potential endophenotypes for BPD as little is known about the heritability of GBRs. The present study aimed to examine whether GBRs derived from two auditory tasks, the oddball task and the dual-click paradigm, are potential BPD endophenotypes.
Methods: A total of 308 subjects were included in this study: 198 healthy controls, 59 BPD patients (22 monozygotic BPD twins and 37 BPD patients from 31 families), and 51 unaffected relatives. The evoked gamma responses were calculated using a Morlet wavelet transformation. Structural equation modelling was applied to obtain the genetic (heritability) and environment estimates in each GBR variable and their (genetic) overlap with BPD.
Results: The heritability estimates of GBR to standard stimuli were 0.51 and 0.35 to target stimuli in the oddball task. However, neither response type was impaired in BPD patients or their unaffected relatives. The heritability estimates of GBR to S1 stimuli were 0.54 and 0.50 to S2 stimuli in the dual-click paradigm. BPD patients had reduced gamma power and suppression to S1 stimuli but their unaffected relatives did not.
Conclusions: Evoked GBRs are heritable traits. However, GBR deficits are not observed in clinically unaffected relatives nor associated with BPD. Gamma responses do not appear to satisfy criteria for being BPD endophenotypes.