Genetic risk for bipolar disorder and schizophrenia predicts structure and function of the ventromedial prefrontal cortex

• Published in: Journal of psychiatry & neuroscience Vol. 46; no. 4; pp. E441 - E450
• Main Authors: Abé, Christoph, Petrovic, Predrag, Ossler, William, Thompson, William H, Liberg, Benny, Song, Jie, Bergen, Sarah E, Sellgren, Carl M, Fransson, Peter, Ingvar, Martin, Landén, Mikael
• Format: Journal Article
• Language: English
• Published: Canada CMA Joule Inc 01-07-2021; CMA Impact, Inc
• Subjects: Aging - genetics; area; association; Bipolar disorder; Bipolar Disorder - diagnostic imaging; Bipolar Disorder - genetics; Brain; Cognitive ability; cortical thickness; Female; Functional magnetic resonance imaging; Genetic aspects; Genetic factors; Genetic Predisposition to Disease; Genomics; Health aspects; Health risk assessment; human cerebral-cortex; Humans; Magnetic Resonance Imaging; Male; Medical imaging; Medicin och hälsovetenskap; Mental disorders; mri; Multifactorial Inheritance; network; Neuroimaging; Neurosciences & Neurology; Prefrontal cortex; Prefrontal Cortex - diagnostic imaging; Prefrontal Cortex - pathology; Prefrontal Cortex - physiopathology; Psychiatry; Psychological aspects; Psychosis; Psykiatri; Research Paper; Risk Factors; Schizophrenia; Schizophrenia - diagnostic imaging; Schizophrenia - genetics; segmentation; self; Structure-function relationships; surface-based analysis; Time series; variants; Sweden
• ISSN: 1180-4882; 1488-2434; 1488-2434
• DOI: 10.1503/jpn.200165

Bipolar disorder is highly heritable and polygenic. The polygenic risk for bipolar disorder overlaps with that of schizophrenia, and polygenic scores are normally distributed in the population. Bipolar disorder has been associated with structural brain abnormalities, but it is unknown how these are linked to genetic risk factors for psychotic disorders.
We tested whether polygenic risk scores for bipolar disorder and schizophrenia predict structural brain alterations in 98 patients with bipolar disorder and 81 healthy controls. We derived brain cortical thickness, surface area and volume from structural MRI scans. In post-hoc analyses, we correlated polygenic risk with functional hub strength, derived from resting-state functional MRI and brain connectomics.
Higher polygenic risk scores for both bipolar disorder and schizophrenia were associated with a thinner ventromedial prefrontal cortex (vmPFC). We found these associations in the combined group, and separately in patients and drug-naive controls. Polygenic risk for bipolar disorder was correlated with the functional hub strength of the vmPFC within the default mode network.
Polygenic risk is a cumulative measure of genomic burden. Detailed genetic mechanisms underlying brain alterations and their cognitive consequences still need to be determined.
Our multimodal neuroimaging study linked genomic burden and brain endophenotype by demonstrating an association between polygenic risk scores for bipolar disorder and schizophrenia and the structure and function of the vmPFC. Our findings suggest that genetic factors might confer risk for psychotic disorders by influencing the integrity of the vmPFC, a brain region involved in self-referential processes and emotional regulation. Our study may also provide an imaging-genetics vulnerability marker that can be used to help identify individuals at risk for developing bipolar disorder.