mowinckel-et-al-2014-a-meta-analysis-of-decision-making-and-attention-in-adults-with-adhd.

Introduction

• Cognitive dysfunction is a primary deficiency in ADHD, highlighting issues in attention, impulsivity, and control.

• Many studies confirm functional deficits in ADHD, particularly in pediatric and adolescent populations.

Deficient Reward Processing

• Deficient reward processing has emerged as a critical aspect of ADHD; it can cause cognitive deficits or result from poor executive processes.

• Sagvolden et al. (2005) suggest that sub-optimal dopamine levels lead to difficulties in learning executive function behaviors due to a steeper delay of reinforcement gradient.

• Sonuga-Barke (2003) and Barkley (1997) argue that poor executive processing capabilities lead to lower performance and avoidance of delayed rewards.

• Studies demonstrate decision-making (DM) deficits in ADHD concerning temporal discounting (TD), risky DM, and reinforcement learning (RL).

Persistence of ADHD into Adulthood

• ADHD is not just a childhood disorder; it persists into adulthood with a prevalence of about 4.4%.

• Adult symptoms often manifest as inattention rather than hyperactivity, which is more prominent in children.

• The understanding of DM deficits in adults with ADHD needs further investigation due to motivational and cognitive differences between children and adults.

Domains of Decision-Making

• DM in this context refers to processes leading to action where one of several decision alternatives is selected.

• Key aspects of DM related to ADHD:

  • Reinforcement Learning (RL)

    • Dependent on the dopamine neurotransmitter system, crucial to ADHD theories.

    • Involves significant tasks like the Iowa Gambling Task (IGT), where individuals learn to make advantageous choices.

  • Risky Decision-Making (DM)

    • Refers to situations with uncertain outcomes, e.g., gambling or driving.

    • ADHD adults exhibit risky behavior documented in studies (higher rates of driving errors, substance abuse, and gambling).

  • Temporal Discounting (TD)

    • Children with ADHD often prefer immediate small rewards over larger delayed ones.

    • Various tasks assess this tendency, including Delay Discounting Tasks (DDT).

Continuous Performance Task (CPT)

• The CPT tests attention and vigilance, noting measures like errors of omission and commission.

• Variations between CPT versions complicate comparisons between studies due to differing target and non-target stimuli ratios.

Drift Diffusion Modeling (DDM)

• DDM combines reaction time and accuracy to understand decision-making mechanisms.

• Main parameters:

  • Drift Rate: Speed of evidence accumulation.

  • Boundary Separation: Decision thresholds that need to be surpassed to trigger a response.

• ADHD participants have demonstrated slower processing speed and higher boundary separation in DDM analysis.

Methodology

• The literature search drew from databases, filtering for studies with adult ADHD samples that matched relevant criteria for effect size calculations.

• A total of 59 studies met the inclusion criteria, with a focus on both DM and CPT measures, including aspects like reaction times and error rates.

Results

• The meta-analysis highlights:

  • Small to medium effect sizes exist for both DM and CPT.

  • Strongest effects found for commission errors in CPT and RL in DM.

  • Risky DM shows smaller effect sizes in adults compared to children.

General Discussion

• DM deficits observed in adults with ADHD are comparable to attention deficits.

• The absence of TD deficits in adults was unexpected; there may be insufficient studies available to draw reliable conclusions on this subdomain.

• Findings indicate ADHD adults might adapt strategies to manage reward processing, even if they still display cognitive deficits.

Conclusion

• Adults with ADHD face significant deficits in attention and DM, comparable to those seen in traditional ADHD assessments.

• There's a need for more studies focusing on computerized DM tasks and refining their design to assess adult-specific ADHD characteristics.