Shared and distinct brain patterns in ADHD and bipolar disorder

What is it about?

ADHD and bipolar duisorder are common psychiatric conditions in adults and both are associated with severe impairment and high risk for negative outcomes. Due to the overlap of certain symptoms, including emotional instability, restlessness and distractibility, there can be uncertainty regarding the distinction between the two disorders in some cases, which can lead to incorrect diagnosis and treatment. We recorded the brain activity of 20 women with ADHD, 20 women with bipolar disorder and 20 women without either disorder using EEG (electroencephalography), which measures patterns of brain activity using non-invasive electrodes placed on the scalp. These brain patterns were assessed while participants performed a computerised cognitive task. This assessment was designed to measure levels of attention and the ability to inhibit an incorrect response. Women in the control group showed an expected increase in brain activity when withholding (or inhibiting) their responses, whereas a significantly smaller brain response was observed in both women with ADHD and women with bipolar disorder. This suggests that when the ADHD and bipolar disorder groups needed to inhibit incorrect responses on the tasks, their brains were not processing the information in the same way as controls. According to the authors, this abnormal brain response may explain the inhibition deficits and impulsivity found in both disorders. However, it was women with bipolar disorder who showed an additional impairment. Compared to the ADHD and control groups, they displayed a weaker brain response related to the ability to monitor their own performance and select correct responses. The researchers suggest that, for women with bipolar disorder, their brains may work less efficiently when it comes to monitoring their own performance on a task.

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Why is it important?

Our study has identified both unique and shared brain patterns in ADHD and bipolar disorder. The identification of distinct brain patterns between these disorders may in the future serve as a ‘biomarker’ to aid in the accurate diagnosis of ADHD and bipolar disorder in the case of people presenting with features of both conditions.

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