Brain activation differences hint at developing course of bipolar disorder

By Eleanor McDermid, Senior medwireNews Reporter

Results of an activation likelihood estimation (ALE) meta-analysis highlight the differences and similarities in brain activation between youths and adults with bipolar disorder.

The analysis included 21 studies in paediatric patients (<18 years), 73 in adults and two that included distinct paediatric and adult groups. An ALE meta-analysis identifies areas with altered activation across the included studies (convergence of activation), by assessing the data according to the spatial coordinates used in those studies.

“Our findings suggest potentially unique neurodevelopmental alterations associated with [bipolar disorder] in youths vs adults that require further study to determine their longitudinal progress and if they may be used to improve diagnosis or treatment”, say Ezra Wegbreit (Brown University Alpert Medical School, Rhode Island, USA) and co-workers.

In the primary analysis of emotional face perception, both paediatric and adult bipolar patients had areas of convergence of hyperactivation and hypoactivation, relative to mentally healthy controls. However, convergence of hyperactivation was significantly greater in paediatric than adult patients for the right amygdala.

Reduced size of the amygdala and increased activation during emotional face perception in youths with bipolar disorder “are among the most replicated neuroimaging findings of any disorder or age group”, the researchers write in JAMA Psychiatry.

They urge further study of this, “potentially as the target of biologically based treatments, including computer-assisted cognitive remediation.”

There were similar results for other types of emotional challenge, with, again, both paediatric and adult patients differing from controls, but paediatric patients having significantly greater convergence of hyperactivation than the adults, in this case for the left inferior frontal gyrus and precuneus.

During cognitive challenges, there were no differences between the patient groups for convergence of hyperactivation, but the paediatric group had significantly more convergence of hypoactivation than the adult group in the right pregenual anterior cingulate cortex.

Wegbreit et al say that further studies are needed, including follow-up of youths with bipolar disorder as they mature, to monitor the developmental progression of these neural alterations, “which may ultimately aid biologically based approaches to diagnosis and treatment for [bipolar disorder].”

They also note that, besides highlighting differences between the age groups, their study also reveals abnormalities common to both, with areas including the ventral prefrontal cortex, amygdala, striatum and posterior visual perception areas.

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