Cortical Folding Patterns Related to Bipolar Disorder Subtypes

Bipolar disorder (BD) is likely not associated with generalized abnormalities of sulcation, but is associated with localized changes of cortical folding among patients with a heavy neurodevelopmental loading, according to research published in Bipolar Disorders. The findings suggest that BD is heterogeneous but may be disentangled using magnetic resonance imaging.

Researchers investigated whole-brain cortical sulcation among 263 patients with BD with high neurodevelopmental load and 320 control patients. Magnetic resonance imaging images were processed with an automatized pipeline to extract the global sulcal index (g-SI) and the local sulcal indices (l-SIs) from 12 a priori determined brain regions. Researchers compared l-SI and g-SI between patients with and without early-onset BD and between patients with and without a history of psychosis, adjusting for age, sex, and handedness.

The magnetic resonance imaging acquisitions and structured clinical interviews differed between sites, introducing diagnostic and measurement heterogeneity, which presents a limitation to the study.

Patients with early-onset BD presented a higher l-SI in the right prefrontal dorsolateral region, and patients with psychotic BD had a decreased l-SI in the left superior parietal cortex. There were no group differences in g-SI or l-SI between healthy participants and the patient cohort. These findings suggest subgroup-specific differences in sulcation among patients with BD, which may be specific to patients with putative neurodevelopmental impairment. The data support a hypothesis that “BD is a heterogeneous clinical entity that may be partially disentangled using brain imaging,” according to researchers.

Further investigation is needed to examine how early neurodevelopmental deviations contribute to the pathophysiology of BD and how exposure to postnatal environmental factors during childhood and adolescence lead to BD onset in early adulthood.

Reference

Sarrazin S, Cachia A, Hozer F, et al. Neurodevelopmental subtypes of bipolar disorder are related to cortical folding patterns: an international multicenter study [published online July 6, 2018]. Bipolar Disord. doi:10.1111/bdi.12664