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EEG-based Word Association Paradigm for Adult ADHD Screening: An Exploratory Pilot Study
Caroline Peng, Tony Russell-Rose
TL;DR
Adult ADHD screening is challenged by long waits and subjective assessments that struggle to distinguish comorbid disorders. This pilot combines EEG and interviews across three word association tasks, finding no significant group differences in EEG biomarkers but a significant semantic-distance difference in free association. The authors conclude that word association may capture group differences not detected by traditional EEG biomarkers, while emphasizing that larger samples are needed to confirm the findings.
Problem
Adult ADHD screening faces long diagnostic waits, and subjective assessments such as the ASRS struggle to distinguish ADHD from comorbid psychiatric disorders.
Source: §1 · p. 1Method
Results
Free association showed a significant semantic-distance group effect (p = 0.003), while the EEG biomarkers showed no significant group differences.
Source: §4.1 · pp. 3–4, §4.2.1 · p. 4Takeaways & Limitations
The pilot suggests word association tasks may reveal cognitive differences not detected by traditional EEG biomarkers, but whether this signal is more robust or scalable remains to be confirmed with larger samples.
Source: §6 · pp. 5–6With five participants per group, the study has limited power and generalisability for between-group comparisons.
Source: §5.3 · pp. 4–5
Abstract
from arXiv · showhide
With the prevalence of Attention Deficit Hyperactivity Disorder (ADHD) over the past decades, healthcare systems across the globe face critical diagnostic challenges due to long diagnostic waiting times and a reliance on subjective behavioural assessments that cannot distinguish ADHD from comorbid psychiatric disorders, especially for adult patients. This exploratory study investigates whether EEG-based word association paradigms show promise as a complementary approach to screening for ADHD in adults. Using a mixed-method approach, the study examines neurological and cognitive differences between neurotypical individuals (NT), clinically diagnosed ADHD participants (ND), and self-reported ADHD cases awaiting formal diagnosis (SR) across three word association tasks. While established EEG biomarkers (ERP N400, Theta/Beta Ratio, and Alpha Suppression) show no significant group differences, semantic distance analysis reveals a statistically significant main effect ($p=0.003$), with the SR group showing the most divergent associations. These preliminary findings suggest that word association paradigms may capture cognitive differences not detected by standard EEG metrics and encourage further large-scale investigation as a potential complement to existing adult ADHD screening tools.
1. INTRODUCTION
Adult ADHD screening is constrained by long waits and subjective tools that struggle to distinguish ADHD from comorbid disorders. This pilot tests whether EEG-based word association tasks could complement screening by identifying neurological and semantic differences.
1. INTRODUCTION
- The ASRS is efficient but struggles to distinguish ADHD from comorbid psychiatric disorders because symptoms overlap.The introduction also describes diagnostic waiting times exceeding 12 months in many healthcare systems.Source: §1 · p. 1
- This pilot examines EEG-based word association tasks as a potential complementary screening approach for adult ADHD.It compares neurological and semantic processing differences between neurotypical and neurodivergent individuals; the authors position the study as exploratory given its small sample (N=15).Source: §1 · p. 1
2. BACKGROUND AND RELATED WORK
Adult ADHD diagnosis faces access and differentiation challenges, while EEG biomarkers show inconsistent replication and adult populations may be heterogeneous. Prior work suggests word association tasks can reveal semantic-processing differences and related neural patterns.
2.1. Diagnostic Challenges
- The ASRS questionnaire cannot distinguish adult ADHD from disorders such as depression or anxiety, amid diagnostic infrastructure focused on childhood presentations.The passage also notes social media misinformation and inappropriate self-reporting cases as added pressures on services.Source: §2.1 · p. 2
2.2. EEG Biomarkers for ADHD
- EEG biomarkers are candidates for objective assessment, but high inter-subject variability and inconsistent replication hinder clinical adoption.The passage notes that adult ADHD symptom trajectories may contribute to greater neurobiological heterogeneity than childhood samples.Source: §2.2 · p. 2
2.3. Word Association and ADHD
- Prior word-association research found greater semantic distance in ADHD participants than neurotypical controls, while EEG work linked creative associations to alpha oscillations.Together, these findings support word association tasks as a way to investigate ADHD-related cognitive differences.Source: §2.3 · p. 2
3. METHODOLOGY
The study combines EEG and interview data to assess three word association tasks as a potential complement to adult ADHD screening. Fifteen participants across three groups completed the tasks and interviews under a standardized procedure, with EEG and semantic measures analyzed alongside participant feedback.
3. METHODOLOGY
- A mixed-method design combines quantitative EEG analysis with qualitative interviews to assess word association tasks as a possible complement to adult ADHD screening.The three tasks were conducted during EEG recording, followed by semi-structured interviews about participant experience and views.Source: §3 · p. 2
3.1. Participants
- Fifteen adults were recruited in three groups: neurotypical controls, clinically diagnosed ADHD participants, and self-reported ADHD participants on NHS waiting lists.Each group included five participants; medication status and psychiatric comorbidities were not systematically recorded or screened.Source: §3.1 · pp. 2–3
3.2. Procedure
- Participants completed three word association tasks during a 15-minute EEG session, then a 10-minute semi-structured interview.Tasks A and B each had 20 trials; COWAT generated 30–80 words per participant, and task order was randomized.Source: §3.2 · p. 3
3.3. Data Analysis
- EEG analysis focused on N400 and alpha suppression at Pz and Theta/Beta Ratio at Fz, F3, and F4; semantic distance used GloVe embeddings.EEG preprocessing included artefact rejection and ICA; exploratory comparisons used one-way ANOVA without correction for multiple comparisons, and interview transcripts underwent thematic analysis.Source: §3.3 · p. 3
4. RESULTS
None of the EEG biomarkers showed statistically significant group differences. Free association showed a significant semantic-distance difference, while paired association and COWAT did not; interviews revealed differing task experiences and views of screening acceptability.
4.1. EEG Results
- None of the EEG biomarkers reached statistical significance across groups; participant-level comparisons limited power to detect moderate differences.The N400 showed no significant group effect despite η2 = 0.162; TBR and alpha suppression also showed no significant group differences.Source: §4.1 · pp. 3–4
4.2.1. Task A: Free Association
- The free-association task showed a significant semantic-distance group effect (F(2, 12) = 9.77, p = 0.003, η2 = 0.62), with SR exceeding ND.SR semantic distance was 0.289 versus 0.241 for ND (p = 0.002, d = −3.55).Source: §4.2.1 · p. 4
4.2.2. Task B: Paired Association
- Paired-association semantic-relatedness judgments showed no significant group differences (p = 0.915, η2 = 0.015).Effect sizes between groups were negligible to small.Source: §4.2.2 · p. 4
4.2.3. Task C: COWAT
- COWAT sequential semantic distance did not differ significantly across groups (p = 0.234, η2 = 0.067), while NT showed the strongest clustering.ND performance varied substantially, with participants generating 43–84 total words.Source: §4.2.3 · p. 4
4.3. Post-study Interviews
- Interviews found that ND and SR participants reported similar attention difficulties, especially during COWAT, while NT participants maintained focus.Eighty percent of ND participants viewed the word association test as more objective than questionnaires; SR and NT participants expressed reservations or mixed views.Source: §4.3 · p. 4
5. DISCUSSION
Established EEG biomarkers did not significantly differentiate groups, while semantic distance was higher for the SR group than the ND group. The discussion also notes limits on group-level inference and on how well corpus-based semantic measures represent individual networks.
5.1. EEG Biomarkers
- No established EEG biomarker significantly differentiated groups, despite effect sizes of η2 = 0.162 for N400 and η2 = 0.240 for TBR.The authors relate the nonsignificant findings to high inter-subject variability, particularly in ND, and the current sample size.Source: §5.1 · p. 4, Table 1 · p. 5
5.2. Semantic Distance
- Semantic distance was significantly higher for SR than ND (p = 0.003), while possible explanations include divergent thinking, treatment-related compensation, or group differences that remain unresolved.The authors also suggest aggregated semantic measures may be more stable than EEG at this sample size, but note that alternative explanations cannot be ruled out.Source: §5.2 · p. 4
5.3. Limitations
- N = 5 per group limits between-group power and generalisability; unrecorded medications and comorbidities and corpus-based GloVe distances further constrain interpretation.The authors recommend larger, more diverse samples, consistent methods, and tighter clinical controls.Source: §5.3 · pp. 4–5
6. CONCLUSION
The pilot found that word association tasks revealed cognitive differences not detected by traditional EEG biomarkers, but does not support a simple EEG biomarker-based screening tool. Its findings are preliminary and underscore complexity and heterogeneity in ADHD assessment.
6. CONCLUSION
- The results do not support developing a simple EEG biomarker-based ADHD screening tool.The study presents the findings as preliminary insights into ADHD characteristics and objective assessment approaches.Source: §6 · pp. 5–6
- Word association tasks, particularly free association, revealed group cognitive differences not detected by traditional EEG biomarkers.The authors suggest computational semantic measures may provide a more detectable signal at this sample size, while noting that any advantage remains to be confirmed in larger samples.Source: §6 · p. 6
- The authors emphasize substantial heterogeneity within ADHD populations and the need for assessment approaches that account for individual differences.Whether semantic measures' apparent advantage reflects greater robustness or scalability remains to be confirmed with larger samples.Source: §6 · p. 6