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Child Psychiatrist /Adult Psychiatrist

Pediatric Bipolar Disorder and ADHD Have Shared Neural Substrate Alterations

Updated: 4 days ago

The similarities in clinical phenotypes between PBD and ADHD may be caused by decreased gray matter volumes in the insula and anterior cingulate cortex seen in both conditions.

Pediatric bipolar disorder (PBD) and attention-deficit/hyperactivity disorder (ADHD) were found to have both shared and distinct alterations in gray matter volumes (GMVs). These findings from a systematic review and meta-analysis were published in the Journal of the American Academy of Child & Adolescent Psychiatry.

Child & Adolescent Psychiatry

Among children, PBD and ADHD frequently co-occur and can affect similar cognitive and affective functions. However, both conditions also have unique, non-overlapping characteristics (eg, PBD typically affects executive functioning whereas ADHD affects attention and working memory). To compare the underlying neurobiological bases of these 2 conditions, investigators searched publication databases from inception through January 2022 for neuroimaging studies that compared PBD or ADHD groups to healthy controls in order to identify common and distinct neural substrates.

A total of 42 articles were included for analysis, of which 32 assessed ADHD and 10 investigated PBD. The pooled sample size comprised 1333 cases with ADHD and 1308 controls and 268 cases with PBD and 385 controls, respectively.

The patient groups with PBD and ADHD comprised 51% and 21% girls (P <.001) and they were 16.2 and 12.8 years of age (P <.001) on average, respectively. The control groups for both conditions were age- and gender-matched with cases.

The investigators found shared GMV changes among the ADHD and PBD groups, with decreased volumes in the right insula (peak coordinates: 50, -4, 0; z=1.615; cluster size=100) and right anterior cingulate cortex (peak coordinates: 2, 26, -14; z=1.683; cluster size=22). These areas correspond with the functions of emotion processing and attention, respectively.

In comparing PBD and ADHD cases, the PBD group had smaller GMVs than cases with ADHD in the right inferior frontal gyrus (peak coordinates: 52, 20, 26; z=1.682; cluster size=835), left orbitofrontal cortex (peak coordinates: 0, 24, -26; z=1.664; cluster size=261), and left hippocampus (peak coordinates: -20, -14, -10; z=1.517; cluster size=188). Conversely, cases with ADHD had greater GMV decreases than cases with PBD in the left precentral gyrus (peak coordinates: -40, -8, 56; z= -2.017; cluster size=158), left inferior frontal gyrus (peak coordinates: -26, 16, -24; z= -2.081; cluster size=59), and right superior frontal gyrus (peak coordinates: 26, 68, 0; z= -1.950; cluster size=28).

When compared with controls, PBD cases had reduced GMVs in the left orbitofrontal cortex, left amygdala, and right inferior frontal gyrus. Cases with PBD had larger GMV in the left hippocampus associated with increasing age (R2, 0.276; P <.001) and boys had greater GMV abnormalities in the left hippocampus relative to girls. Cases with ADHD had decreased GMVs in the right anterior cingulate cortex, right insula, left precentral gyrus, and left inferior frontal gyrus and increased GMV in the bilateral thalamus relative to controls. Smaller GMV in the left inferior frontal gyrus was observed with increasing age among cases relative to controls (R2, 0.392; P <.001).

Study authors concluded, “Overlapping anatomic substrates may account for similarities in the clinical presentation of PBD and ADHD, while disorder-differentiating regional alterations may account for the greater affective disturbances in PBD and greater neurocognitive and motor function disturbances in ADHD.”

These study findings may be limited by the use of peak coordinate data instead of raw brain map data.

Disclosure: Multiple study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

This article originally appeared on Psychiatry Advisor

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