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Bipolar disorder affects brain regions controlling inhibition, emotion

Analysis of a large sample indicated widespread bilateral patterns of reduced cortical thickness in adolescents and adults with bipolar disorder.

“[Bipolar disorder] is known to be highly heritable with individual risk depending partially on genetics. However, the underlying neurobiological mechanism of the disorder remains unclear. The prognosis for individuals with [bipolar disorder] is mixed: currently approved medications are ineffective for many patients,” Derrek Hibar, PhD, of the University of Southern California, Marina del Rey, and colleagues wrote.

To better understand pathophysiology of bipolar disorder, researchers assessed cortical gray matter thickness and surface area measures from brain MRI scans of 1,837 individuals with bipolar disorder and 2,582 healthy controls.

Participants with bipolar disorder exhibited thinner cortical gray matter in frontal, temporal and parietal regions of both brain hemispheres.

Bipolar disorder had the largest effect on left pars opercularis, left fusiform gyrus and left rostral middle frontal cortex.

When accounting for age at the time of MRI, longer illness duration was associated with reduced cortical thickness in frontal, medial parietal, and occipital regions.

Commonly prescribed medications, including lithium, antiepileptic and antipsychotic treatments were significantly associated with cortical thickness and surface area. This remained when accounting for participants who received multiple medications.

A history of psychosis was associated with reduced cortical surface area, but mood state at time of scan was not.

“This new map of the bipolar brain gives us a roadmap of where to look for treatment effects,” study researcher Paul Thompson, PhD, of the University of Southern California and director of the ENIGMA consortium, said in a press release. “By bringing together psychiatrists worldwide, we now have a new source of power to discover treatments that improve patients' lives.” – by Amanda Oldt

Disclosure: Hibar reports no relevant financial disclosures. Please see the study for a full list of relevant financial disclosures.