RESEARCH: Data‐driven identification of subtypes of executive function across typical development, ADHD, and ASD (2020)

POST SUMMARY
This study looks at the executive function (EF) and brain scans of ADHD, autistic, or neurotypical children between the ages of 8-17 to find EF subgroups. They have found three: those that struggled most with (1) flexibility & emotional regulation; (2) inhibitory control and impulsivity; and (3) working memory, organizing, and planning. All three groups of children were spread out over all three subtypes, and in the brain scans there were more differences within same diagnoses than there were within these cross-diagnostic EF subtypes. This is important because treatments such as stimulants, cognitive training, or cognitive behavioral therapy each differently target the three subtypes.

Data‐driven identification of subtypes of executive function across typical development, attention deficit hyperactivity disorder, and autism spectrum disorders (2020)

  • Vaidya, C.J., You, X., Mostofsky, S., Pereira, F., Berl, M.M. and Kenworthy, L., Journal of Child Psychology and Psychiatry
ABSTRACT

Article Highlights:

  • Impairment of executive function (EF), the goal-directed regulation of thoughts, actions, and emotions, drives negative outcomes and is common across neurodevelopmental disorders…”
    • One of the main difficulties in figuring out how to help executive dysfunction (EDf) is that EDf varies so much, both within and across conditions
  • “We observed three trans-diagnostic EF subtypes characterized by behavioral profiles that were defined by relative weakness in:”
    • “(a) behavioral flexibility and emotion regulation (FLEX- EMOT);
    • (b) hyperactivity/impulsivity and inhibition (INHIBIT); and
    • (c) working memory, organizing, and planning (METACOG).”
  • Even the TD [typically developing/neurotypical] children fell into these three categories, suggesting that the link between these certain EFs are normal in children and that “disordered EF is nested within normal variability.”

ADHD & Autism

  • “A large proportion of autistic children meet criteria for ADHD (41%–78%…).”
    • “Furthermore, 1 in 5 children diagnosed with ASD have a pre-existing ADHD diagnosis”
  • Comorbid ADHD exacerbates ASD social symptoms… and relates to worse:
    • adaptive function…
    • quality of life…
    • and intervention outcomes…”
  • “Furthermore, impairment is progressive, increasing from childhood to adolescence…
    • persistent, continuing despite amelioration of core ASD symptoms…
    • and drives negative outcomes…”

Participants:

  • Participants were two cohorts of mostly males (62.5% and 67.9%, respectively) between 8-17 years old with IQs > 70 and no medical diagnoses. Between the two groups there were 240 autistic, 307 ADHD, and 465 TD participants.

EF Subtypes across ADHD & ASD

  • The results showed that there are more similarities in the frontal-parietal recruitment of the brains of people in the same EF subtype, regardless of whether the brains belonged to someone who was TD, ASD, or ADHD, than there were between scans of people with the same diagnosis.
  • EF profiles spanned the normal to impaired spectrum,” “manifested as dispositional traits at the normative end and psychopathology at the maladaptive end.”
    • The TD children were fairly evenly distributed among all three subgroups, however:
    • the FLEX-EMOT subgroup had more ASD participants
    • the INHIBIT subgroup had more ADHD participants.
  • These findings are important for getting people the appropriate treatment as “[m]any evidence- based treatments for EF in children with developmental disabilities target specific ‘subtypes’ of EF deficit, for example:
    • central stimulants are evidence- based for inhibition, working memory and attention deficits,
    • while the computer-based treatment Cogmed improves working memory specifically…
    • and the cognitive-behavioral treatment Unstuck and On Target improves flexibility…”

EF Subtypes & rethinking diagnostic criteria

  • The results showed the insufficiency of the current diagnostic criteria for ADHD in the DSM.
    • Because, while “INHIBIT maps to Hyperactivity/Impulsivity”
    • Different groups of children being tested had differing levels of inattention between the INHIBIT and METACOG groups,
      • suggesting that focusing on a patient’s level of inattention has “limited utility as a distinguishing feature.”
    • In addition, 19% of ADHD children were in the FLEX-EMOT group, which is not explained by the current DSM diagnostic criteria or subtypes,
      • “…community detection applied to temperamental traits in ADHD revealed segregation by positive and negative emotion regulation problems…which suggests that FLEX- EMOT profile may be further segregated upon deeper phenotyping.”
  • Importantly, among ASD children “only half of the samples in each cohort showed the FLEX-EMOT profile, which challenges the often held notion of cognitive inflexibility as the hallmark EF comorbidity in ASD”

Future Research:

  • “Further, deeper phenotyping would be helpful to parse the type of difficulties in regulating externalizing behaviors (e.g., rule-breaking vs. aggression) that are associated with disinhibition or inflexibility.”
  • “Future neuroimaging studies can identify the ‘signatures’ of activation and connectivity patterns that signify EF subtype, with AUC values [severity] serving as a continuous dimension to probe the EF profile spectrum.”
  • “Additionally, whether the observed tripartite structure is stable developmentally and generalizes beyond ADHD and ASD diagnoses and in a broader age range needs to be tested in future work,” as does establishing “the clinical importance of the observed tripartite structure by testing predictive validity for outcomes (e.g., treatment efficacy)”

CITATION

Vaidya, C.J., You, X., Mostofsky, S., Pereira, F., Berl, M.M. and Kenworthy, L. (2020), Data‐driven identification of subtypes of executive function across typical development, attention deficit hyperactivity disorder, and autism spectrum disorders. J Child Psychol Psychiatr, 61: 51-61. doi:10.1111/jcpp.13114

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