Lecture 13 - Attention and impulsivity

The Social Brain: Critical Perspectives on Science, Society and Neurodiversity

Richard Ramsey

Today


Part 1

  • Attention and impulsivity


Part 2

  • Read articles and discuss



Overview


  • Background & ADHD
  • Performance on executive function tasks
    • Behavioural evidence
    • Neurobiological evidence

Background & ADHD

Living with ADHD

ADHD

  • Attention Deficit/Hyperactivity Disorder (ADHD) is defined by a combination of symptoms of
    • Inattention
    • Hyperactivity/impulsivity
  • 3 types:

Diagnosis

  • Six (or more) of the following symptoms of inattention or hyperactivity-impulsivity have persisted for at least 6 months to a degree that is maladaptive and inconsistent with developmental level. Some examples as follows:

  • Inattention

    • Often does not give close attention to details or makes careless mistakes in schoolwork.
    • Often has trouble keeping attention on tasks or play activities.
    • Often does not seem to listen when spoken to directly.

  • Hyperactivity-impulsivity

    • Often fidgets with hands or feet or squirms in seat.
    • Often gets up from seat when remaining in seat is expected.
    • Often runs about or climbs when and where it is not appropriate.

Features

  • Peak onset between the age of 3 and 4
  • Affects 3%-5% children, prevalence higher in areas of socio-economic disadvantage
  • Male/Female ratio
    • 4:1 for the hyperactivity/impulsivity type
    • 2:1 for the inattention type
  • Co-morbidity: 50% of the children also show another psychiatric disorder:
    • Learning difficulties, Oppositional Defiant Disorder and Conduct Disorder, Anxiety and mood disorders, Substance abuse, Tic disorders
  • Medical/Physical characteristics:
    • More accident prone, Sleep problems
    • Persists in adolescence for around 50-80% of individuals and in adulthood for around 30-50% of individuals

Genetics

  • Disorder clusters in families
    • Increased risk for 1st and 2nd order degree relatives (Faraone et al. 1995)
    • Siblings are 3 to 5 times more at risk (Biederman et al., 1992, Faraone et al., 1993)
    • Concordance is higher in monozygotic twins (50%-80%) than dizygotic twins (33%) (Bradley & Golden, 2001)

Several candidate genes (Durston & Konrad, 2007), some linked to dopaminergic system and others to the serotonergic system. Likely to have a complex genetic origin

Cold vs hot executive tasks


  • “Cold” executive functions tasks are associated with working memory, inhibition and planning.

  • “Hot” executive function tasks are associated with reward and reinforcement mechanisms

Stroop task


Stroop task processes


Delay aversion


  • Greater preference for smaller-immediate over larger-delayed rewards (choice impulsivity)

  • 1CHF now or 100 CHF in a year?

    • At which point do you shift your choice?

  • Marshmallow test for kids. One now or two later?

Marshmallow test

Performance on executive function tasks

  • Behavioural evidence
  • fMRI evidence

Behavioural evidence


  • Review of 8 meta-analyses:

    • Large effect: >0.50
    • Medium effect: 0.50-0.30
    • Small effect: <0.30

(Nigg, 2005)

Nigg 2005 results

Nigg 2005 results

Neurobiological evidence

  • Functional MRI studies reveal atypical activity in
    • Prefrontal cortex (esp. right inferior frontal)
    • Basal ganglia (esp. putamen)
    • Cerebellum
    • Parietal areas

(Casey & Durston, 2006; Rubia, 2018)

Response suppression task

(Rubia et al., 2005; Rubia, 2018)

Response suppression results

(Rubia et al., 2005; Rubia, 2018)

“Cold” task summary


Individuals with ADHD show:

  • Atypical performance in EF tasks

  • Atypical neural responses compared to controls in “cold” EF tasks

  • What about “hot” tasks?

Reward task

(Ströhle et al., 2008)

Reward results

(Ströhle et al., 2008)

Reward results

(Ströhle et al., 2008)

Summary


Individuals with ADHD show:

  • Atypical performance in EF tasks

  • Atypical neural responses compared to controls in “cold” and “hot” EF tasks

However…

Individual differences - Nigg 2005

Individual differences

When ADHD children tested on both inhibition and delay aversion and looking at individual performances rather than group performance:

  • 23% deficit on both
  • 23% inhibition deficit only
  • 15% delay aversion deficit only
  • 39% no apparent deficit on any of the two

So what does this mean?

(Nigg, 2005)

Single cognitive mechanism?



Inhibition

Reward

Future research

  • Is there good evidence for a single cognitive deficit hypothesis?

  • How well does a deficit in inhibition or motivation/reward processing explain the clinical symptoms associated with ADHD?

  • Is it plausible to assume a single core deficit? What are the alternative options? And what are the implications for designing effective interventions?

(Castellanos et al., 2006; Rubia, 2018; Sonuga-Barke, 2005)

Take a break

Part 2 - Read and discuss

Discussion material


  • break into small groups (~ 5 per group)

  • discuss aspects of the lecture

  • discuss aspects of the journal article: Rubia, 2018

  • There is no need to read all of the paper. Pick a section of the paper that interests you and focus on that for the discussion.

References

Casey, B. j., & Durston, Ph. d., Sarah. (2006). From Behavior to Cognition to the Brain and Back: What Have We Learned From Functional Imaging Studies of Attention Deficit Hyperactivity Disorder? American Journal of Psychiatry, 163(6), 957–960. https://doi.org/10.1176/ajp.2006.163.6.957
Castellanos, F. X., Sonuga-Barke, E. J. S., Milham, M. P., & Tannock, R. (2006). Characterizing cognition in ADHD: Beyond executive dysfunction. Trends in Cognitive Sciences, 10(3), 117–123. https://doi.org/10.1016/j.tics.2006.01.011
Nigg, J. T. (2005). Neuropsychologic Theory and Findings in Attention-Deficit/Hyperactivity Disorder: The State of the Field and Salient Challenges for the Coming Decade. Biological Psychiatry, 57(11), 1424–1435. https://doi.org/10.1016/j.biopsych.2004.11.011
Rubia, K. (2018). Cognitive Neuroscience of Attention Deficit Hyperactivity Disorder (ADHD) and Its Clinical Translation. Frontiers in Human Neuroscience, 12. https://doi.org/10.3389/fnhum.2018.00100
Rubia, K., Smith, A. B., Brammer, M. J., Toone, B., & Taylor, E. (2005). Abnormal Brain Activation During Inhibition and Error Detection in Medication-Naive Adolescents With ADHD. American Journal of Psychiatry. https://doi.org/10.1176/appi.ajp.162.6.1067
Sonuga-Barke, E. J. S. (2005). Causal Models of Attention-Deficit/Hyperactivity Disorder: From Common Simple Deficits to Multiple Developmental Pathways. Biological Psychiatry, 57(11), 1231–1238. https://doi.org/10.1016/j.biopsych.2004.09.008
Ströhle, A., Stoy, M., Wrase, J., Schwarzer, S., Schlagenhauf, F., Huss, M., Hein, J., Nedderhut, A., Neumann, B., Gregor, A., Juckel, G., Knutson, B., Lehmkuhl, U., Bauer, M., & Heinz, A. (2008). Reward anticipation and outcomes in adult males with attention-deficit/hyperactivity disorder. NeuroImage, 39(3), 966–972. https://doi.org/10.1016/j.neuroimage.2007.09.044

Acknowledgements