What Do Electroencephalographic Microstates Have to Say About ADHD?

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For the most part, research on the EEG signatures of ADHD has concentrated on its frequency spectrum or event related evoked potentials. In this study, researchers investigated EEG microstates.

New research from Biological Psychiatry: Cognitive Neuroscience and Neuroimaging supports the utility of electroencephalographic (EEG) microstates (MS) D and A as functional biomarkers for attention-deficit hyperactivity disorder (ADHD).

Between 2001 and May 2018, the researchers recorded 2 minutes of resting-state EEG of 66 adult patients with ADHD (31 women, aged 34.1±11.4 years) and 66 control individuals (41 women, aged 36.5±12.4 years) in the Netherlands. A total of 40 individuals with ADHD had mixed subtype, 23 had “inattentive” subtype, and 3 had “hyperactive” subtype. The ADHD Rating Scale was selected as the best standardized clinical questionnaire to reflect current symptoms of ADHD.

In a separate dataset, researchers obtained 3 minutes of resting-state EEG recordings of 22 patients with ADHD (12 women, aged 32.3±9.2 years) and 22 healthy control individuals (14 women, aged 31.1±7.3 years) at Geneva University Hospitals. This cohort completed the Adult ADHD Self-Report Scale. Diagnosis was based on the ADHD Child Evaluation for Adults (ACE+), the Structured Clinical Interview for DSM-IV Axis II Personality Disorders, and the Diagnostic Interview for Genetic Studies. A total of 16 individuals with ADHD had mixed subtype, 5 had “inattentive” subtype, and 1 patient had “hyperactive” subtype.

The investigators utilized Koenig’s Microstate toolbox for EEGLAB to estimate a microstate map for each dataset and a k=5 global dominant map for the 2 datasets.

Analyzing the first dataset, the investigators found that the ADHD group tended to spend less time in left-right diagonal orientation (A) compared with control individuals (P ≤ .05 d = -0.43). Map D’s fronto-central topography tended to show more global variances P ≤.01, d = 0.71), increased temporal proportion (Time Coverage, P ≤.05, d = 0.59) and longer state durations (mean duration, P ≤.05, d = 0.53) among individuals with ADHD.

Map A time coverage was negatively associated with ADHD total score and ADHD hyperactivity. Map A global explained variance (Gev) and ADHD total score were negatively associated, and mean duration of map A was linked with ADHD total score and ADHD inattention. Pittsburg Sleep Quality Index among individuals with ADHD was linked with Map D global explained variance and time coverage.

Utilizing the second dataset as an out-of-sample validation, the researchers replicated the effect size and statistical significance deviations of map D between the individuals with ADHD and control individuals.

Limitations of the study included the inability to establish causation and possible differences in diagnosing ADHD.

“The combined signature of lower microstate A coverage and increased microstate D duration in our study would imply that ADHD could be characterized as a condition of ‘hyper-vigilance,’ consistent with its behavioral symptoms of physical and emotional hyperactivity,” the researchers said.

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

Reference

Férat V, Arns M, Deiber MP, et al. Electroencephalographic microstates as novel functional biomarkers for adult attention-deficit hyperactivity disorder. Biol PsychiatryCogn Neurosci. 2021, ISSN 2451-9022. doi:10.1016/j.bpsc.2021.11.006