Brain structure and functioning

Brain-imaging tools, such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), allow researchers to take pictures of the living brain at work. These tools help scientists study the brain's structure and activity.

Some imaging studies show how the brains of people with bipolar disorder may differ from the brains of healthy people or people with other mental disorders. For example, one study using MRI found that the pattern of brain development in children with bipolar disorder was similar to that in children with "multi-dimensional impairment," a disorder that causes symptoms that overlap somewhat with bipolar disorder and schizophrenia.²⁰ This suggests that the pattern of brain development in the two conditions may be associated with the risk for unstable moods.

Another MRI study found that the brain's prefrontal cortex in adults with bipolar disorder tends to be smaller and function less well compared to adults who don't have bipolar disorder.^21,22 The prefrontal cortex is a brain structure involved in "executive" functions such as solving problems and making decisions. This structure and its connections to other parts of the brain mature during adolescence, suggesting that abnormal development of this brain circuit may account for why the disorder tends to emerge during a person's teen years.²³ Pinpointing brain changes in youth may help us detect illness early or offer targets for early intervention.

The connections between brain regions are important for shaping and coordinating functions such as forming memories, learning, and emotions, but scientists know little about how different parts of the human brain connect. Learning more about these connections, along with information gained from genetic studies, helps scientists better understand bipolar disorder. Scientists are working towards being able to predict which types of treatment will work most effectively.

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