Neurostructural phenotypes of CACNA1C rs1006737 in adolescents with bipolar disorder and healthy controls.

Objective: Investigate the effects of CACNA1C rs1006737 on cortical and subcortical neurostructural phenotypes in Caucasian bipolar disorder (BD) and healthy control (HC) adolescents.
Methods: Seventy-one adolescents (14-20 years; 38BD, 33HC) underwent 3-Tesla Magnetic Resonance Imaging (MRI). Region of interest (ROI) and vertex-wise analyses examined cortical volume, surface area (SA), and thickness, as well as subcortical volume. ROIs included the ventromedial prefrontal cortex (vmPFC), ventrolateral prefrontal cortex (vlPFC), anterior cingulate cortex (ACC), putamen, and amygdala. General linear models included main effects of diagnosis and rs1006737, and an interaction term, controlling for age, sex, and total intracranial volume.
Results: Vertex-wise analysis found significant BD-by-rs1006737 interactions for prefrontal and occipital regions such that BD A-carriers were found to have greater SA relative to BD non-carriers, while HC A-carriers had reduced SA relative to HC non-carriers. ROI analysis found an interaction in the ACC such that BD A-carriers were found to have greater SA relative to BD non-carriers, while no significant difference was found in HCs. Main effects of rs1006737 were also found on ACC SA from ROI analysis, and occipital SA from vertex-wise analysis, such that A-carriers had larger SA relative to non-carriers in both of these regions.
Conclusions: The current study identified neurostructural intermediate phenotypes relevant to the impact of CACNA1C rs1006737 on adolescent BD. Further investigation is warranted into the neurofunctional and neurocognitive relevance of rs1006737 associations with BD-specific elevations in regional SA.
Competing Interests: Declaration of Competing Interest Dr. Metcalfe is Director of Research of Canadian Health Solutions, Inc. and Canadian Imaging Research Centre. Canadian Health Solutions provides medical assessment services to institutional insurers in Canada. Canadian Imaging Research Centre provides imaging research services and diagnostics development for clients. The current research is unrelated to these roles and Dr. Metcalfe's contribution to the current research predates these roles. Dr. Kennedy is a member of the Scientific Advisory Board of Myriad Neuroscience (unpaid), and holds several patents relating to pharmacogenetic tests for psychiatric medications. All other authors declared no potential conflicts of interest.
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