Verbal working memory involves temporarily storing and manipulating verbal information to guide behavior.
Processing speed refers to the rate at which individuals can take in visual information, process it, and respond.
Deficits in these key executive functions are commonly associated with ADHD. The disorders’ hallmark symptoms like inattention and distractibility may stem from inadequate working memory and slow processing – together these could reduce one’s capacity to maintain focus on tasks and regulate behavior effectively.
Anker, E., Ogrim, G., & Heir, T. (2022). Verbal working memory and processing speed: Correlations with the severity of attention deficit and emotional dysregulation in adult ADHD. Journal of Neuropsychology, 16(1), 211-235. https://doi.org/10.1111/jnp.12260
Key Points
- The study aimed to examine if verbal working memory and processing speed, as measured by psychometric tests, can indicate the severity of attention deficits and emotional dysregulation in adults with ADHD.
- 418 adults diagnosed with ADHD as per DSM-5 criteria participated. Attention deficit severity was measured using the ASRS inattentive subscale. Emotional dysregulation was measured using the Deficient Emotional Self-Regulation (DESR) scale.
- Verbal working memory and processing speed were assessed using the Working Memory Index (WMI) and Processing Speed Index (PSI) from the WAIS-III intelligence test.
- Participants had normal full-scale IQ. As expected, they showed reduced WMI and PSI compared to normative scores.
- Only processing speed was weakly associated with attention deficits. No significant associations were found between verbal working memory/processing speed and emotional dysregulation severity.
- The findings indicate the limited utility of using WMI and PSI scores to determine the severity of core ADHD symptoms like attention deficits and emotional dysregulation.
Rationale
ADHD diagnosis relies heavily on subjective clinical assessments (Barkley et al., 2002). Prior research shows neuropsychological tests (a standardized assessment method used to objectively measure cognitive abilities like memory, attention, processing speed, and executive functions) can objectively measure cognitive deficits seen in ADHD (Willcutt et al., 2015).
However, it is unclear if test performance correlates with and can indicate the severity of core ADHD symptoms like attention deficits and emotional dysregulation (Fabio & Caprì, 2017).
This knowledge gap is addressed by examining if verbal working memory and processing speed relate to severity of attention and emotional regulation issues in adults with ADHD.
Method
The study utilized an observational cross-sectional design. The sample comprised 418 adults (ages 18-60 years) diagnosed with ADHD based on DSM-5 criteria (APA, 2013). Symptom severity in two core deficit areas was examined: attention deficits and emotional dysregulation.
Attention deficit severity was measured using scores on the inattentive dimension of the Adult ADHD Self-Report Scale (ASRS) (Kessler et al., 2005).
The inattentive portion includes 9 items assessing the severity of attention difficulties like failure to pay close attention to details, difficulty sustaining focus, problems with organization, forgetfulness, etc.
Emotional dysregulation severity was assessed using the Deficient Emotional Self-Regulation (DESR) questionnaire (Biederman et al., 2012), which consists of 8 items examining tendencies like extreme emotional reactivity, angry outbursts, and difficulty calming down when upset.
Two key cognitive functions often impaired in ADHD were also evaluated – verbal working memory and processing speed.
The Working Memory Index (WMI) and Processing Speed Index (PSI) from the Wechsler Adult Intelligence Scale III (WAIS-III) were used to provide standardized scores reflecting deficits in these domains (Wechsler, 1997).
Both subscales include multiple subtests that tax different aspects of working memory and processing efficiency.
Sample
The sample comprised 418 adults between ages 18-60 years who met DSM-5 diagnostic criteria for ADHD based on clinical assessments. 67% were males (n=280) and 33% females (n=138).
Participants were recruited from two psychiatric outpatient clinics. Those with intellectual disability, brain damage, or lacking fluency in native language were excluded.
Statistical Analysis
Associations between the cognitive test indices (WMI, PSI) and symptom severity measures (ASRS-inattention, DESR) were analyzed using multiple linear regression models and Pearson’s correlation coefficients.
Effects of age and gender were controlled for. Alpha level was set at .05 to determine statistical significance.
Results
Despite having an overall IQ in the average range, adults with ADHD exhibited reduced WMI and PSI scores compared to age-matched general population norms. This aligns with prior research showing verbal working memory and processing speed deficits are commonly associated with ADHD.
Linear regression analysis found processing speed (PSI scores) had a small but significant correlation with inattentive symptom severity on the ASRS scale (beta=-0.056, p=0.003).
No significant associations were observed between working memory or processing speed and emotional dysregulation severity per the DESR questionnaire.
The coefficients of determination (R-squared values) for these models were quite small, indicating the cognitive indices accounted for under 10% of variance in attention and emotional regulation difficulties.
This suggests verbal working memory and processing efficiency have limited utility in predicting core symptom severity in adult ADHD samples.
Insight
The findings indicate that despite adults with ADHD showing impaired verbal working memory and processing speed on intelligence tests, the severity of deficits in these cognitive abilities shows little association with core ADHD symptoms like attention deficits and emotional dysregulation.
This implies that performance on verbal working tests cannot be reliably used to determine the severity of attention and emotional regulation issues in those with ADHD.
One potential reason is that tests examine these cognitive functions in a structured environment, unlike real-world situations where ADHD patients struggle with them.
Everyday situations place much higher simultaneous demands on these executive functions. Thus, the study provides useful insight that commonly used neuropsychological tests have limited ecological validity in relation to typical cognitive struggles seen in ADHD and do not capture the severity of patients’ problems.
This highlights the need for more functional assessments that simulate real-world demands to better understand the severity of cognitive-behavioral impairments in adult ADHD.
Strengths
The study had several methodological strengths:
- Use of a large sample size with over 400 adults with confirmed ADHD diagnosis, allowing for robust analysis and results.
- Employment of validated clinical scales like ASRS and DESR to assess core ADHD symptom severity.
- Inclusion of equal gender distribution and a wide adult age range, improving generalizability.
- Reliance on established measures like WMI and PSI from a standardized IQ test to evaluate key cognitive functions impaired in ADHD.
- Use of correlation and regression methods to quantitatively examine associations between variables of interest.
Limitations
However, the study also had certain limitations to note:
- As patients were recruited from just two psychiatric clinics, the sample may not fully represent the diverse ADHD population.
- Lacked a control group of adults without ADHD for comparison on cognitive test performance.
- Cognitive assessments were limited to verbal working memory and processing speed, while other executive functions are also impaired in ADHD.
- Findings cannot infer causality due to the cross-sectional design.
- Did not account for effects of medication or comorbid disorders that can potentially influence test performances.
Implications
The findings highlight issues with ecological validity of neuropsychological tests in assessing real-world cognitive-behavioral impairments seen in ADHD.
The poor correlations indicate that structured pen-and-paper tests, while useful for diagnosis, have limited value in gauging symptom severity.
This knowledge can help shape clinical practice – clinicians should not solely depend on these tests to determine treatment needs or make prognostic predictions.
Instead, they should place greater emphasis on patient functioning through clinical interviews, observations, and subjective reports to understand impairment severity.
The findings also underscore the need for more functional and real-world replicative assessments focusing on attention regulation in daily tasks and emotional regulation in interpersonal situations, to better evaluate the level of impairments.
The development and application of such comprehensive and ecologically valid tools can improve diagnosis and treatment planning for adult ADHD.
References
Primary Reference
Anker, E., Ogrim, G., & Heir, T. (2022). Verbal working memory and processing speed: Correlations with the severity of attention deficit and emotional dysregulation in adult ADHD. Journal of Neuropsychology, 16(1), 211-235. https://doi.org/10.1111/jnp.12260
Other references
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders ( 5th ed.). Arlington, VA: American Psychiatric Publishing. Text Revision. Washington DC.
Barkley, R. A., Fischer, M., Smallish, L., & Fletcher, K. (2002). The persistence of attention-deficit/hyperactivity disorder into young adulthood as a function of reporting source and definition of disorder. Journal of Abnormal Psychology, 111(2), 279. https://doi.org/10.1037/0021-843X.111.2.279
Biederman, J., Spencer, T. J., Petty, C., Hyder, L. L., O’Connor, K. B., Surman, C. B., & Faraone, S. V. (2012). Longitudinal course of deficient emotional self-regulation CBCL profile in youth with ADHD: Prospective controlled study. Neuropsychiatric Disease and Treatment, 8, 267. https://doi.org/10.2147/NDT.S29670
Fabio, R. A., & Caprì, T. (2017). The executive functions in a sample of Italian adults with ADHD: Attention, response inhibition and planning /organization. Mediterranean Journal of Clinical Psychology, 5(3). https://doi.org/10.6092/2282-1619/2017.5.1636
Kessler, R. C., Adler, L., Ames, M., Demler, O., Faraone, S., Hiripi, E. V., … Ustun, T. B. (2005). The World Health Organization Adult ADHD Self-Report Scale (ASRS): A short screening scale for use in the general population. Psychological Medicine, 35(2): 245–256, https://doi.org/10.1017/s0033291704002892
Wechsler, D. (1997). Wechsler adult intelligence scale, technical manual. San Antonio, TX: The Psychological Corporation.
Willcutt, E. G., Doyle, A. E., Nigg, J. T., Faraone, S. V., & Pennington, B. F. (2015). Validity of the executive function theory of attention-deficit/hyperactivity disorder: A meta-analytic review. Biological Psychiatry, 57, 1336–1346. https://doi.org/10.1016/j.biopsych.2005.02.006
Keep Learning
Here are some potential Socratic discussion questions for a college class based on this research:
- Why might performance on cognitive tests like the WMI and PSI not align well with the severity of real-world cognitive-behavioral impairments seen in ADHD? What are the key differences in how executive functions are assessed?
- What additional cognitive and psychosocial factors commonly impaired in ADHD were not examined in this study? Why might including them reveal different results?
- What are some ways in which comorbid conditions might influence results on neuropsychological tests assessing core ADHD deficits? How can this be better controlled for?
- What additional assessments could supplement standardized cognitive tests to better capture real-world impairments faced by adults with ADHD? What might a more ecologically valid evaluation toolkit include?
- How could the study design be improved to establish causal links between cognitive test performances and functional impairments seen in ADHD? What alternative study methods could help advance this research?
- What groups would benefit the most from findings that cognitive test scores have limited validity in determining real-life ADHD impairments? How can this shape best practice recommendations?
