A Dimensional Examination of Childhood Adversity and Neurodevelopment in ADHD

• In Event: Poster Session 01
  In Poster Session: PS 01 Topic - Attention, Learning, Memory

Abstract

Introduction: Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by a pattern of inattention, hyperactivity, and impulsivity that affects approximately 5-7% of children worldwide, interferes with functioning, and persists into adulthood in 60% of patients (American Psychiatric Association [APA], 2013). ADHD is characterized by disrupted brain development; thus, the environmental impact of early life adversity (ELA) on neurodevelopment in children with ADHD is implicated (APA, 2013; McLaughlin, Sheridan, & Lambert, 2014). Given the varying presentations of ADHD and accompanying difficulties across domains, large-scale studies have increasingly suggested that a dimensional approach may be most useful in understanding this disorder, with attention paid to symptom presence and morbidity rather than solely to a dichotomous diagnosis (ADHD vs no ADHD) (Vértes & Bullmore, 2015). The current study examines how neural consequences of ELA, also examined dimensionally as threat and deprivation (McLaughlin & Sheridan, 2014), may coincide with or elevate symptoms of ADHD. This study focuses on the hippocampus, as this region has been implicated in research on ELA (Calem et al., 2017) and ADHD (Al-Amin et al., 2018).

Methods: Participants included 79 children ages 4-10 (Mean = 7.05 years). ADHD symptoms were evaluated on the Preschool Age Psychiatric Assessment (PAPA; Egger & Angold, 2004). ELA was evaluated using the PAPA (Egger et al., 2006), CTS-PC (Lee et al., 2012; Straus et al., 1998), and the CTS-2 (Straus et al., 1996) and coded into dimensions of deprivation and threat. Structural data on the hippocampus was obtained through a whole-brain high-resolution T1-weighted multi-echo structural scan (MPRAGE) of children. 25 children were scanned on a 3T GE Signa EXCITE HD system and 75 children were scanned on a 3T GE MR750 system. Thus, scanner was included as a covariate in all analyses. Hippocampal volume was extracted using the 2005 Desikan-Killiany FreeSurfer atlas (Desikan et al., 2006).
Results: Threat exposure, but not deprivation exposure, was linked to higher levels of ADHD symptoms (t= -2.39, p = .02) and lower hippocampus volume (t = 2.14, p = .04). Hippocampus volume also moderated the link between threat and ADHD symptoms in follow-up analyses at a value approaching significance (t = -1.74, p = .08), such that lower hippocampus volume predicted greater levels of ADHD symptoms for individuals with positive threat exposure histories, and higher hippocampus volume predicted ADHD symptoms for children with negative threat exposure histories.
Conclusion: Results from this study suggest that structural differences in the hippocampus may play a unique role in ADHD for children who have experienced ELA in the form of threat, but not deprivation. Identifying neural structural differences in ELA and ADHD represents an important target for continued research to better understand the possible etiologic and exacerbating roles of ELA in the clinical expression of neurodevelopmental problems in children.

Authors

• Meredith Gruhn, University of North Carolina at Chapel Hill
  Presenting Author

• Laura Machlin, Harvard University
  Non-Presenting Author

• Helen Egger, New York University Langone, Child Study Center
  Non-Presenting Author

• Cheryl Stein, Hassenfeld Children’s Hospital at NYU Langone
  Non-Presenting Author

• Kimberly Carpenter, Duke Univeristy
  Non-Presenting Author

• Kinjal Patel, University of North Carolina at Chapel Hill
  Non-Presenting Author

• William Copeland, University of Vermont
  Non-Presenting Author

• Margaret A. Sheridan, University of North Carolina at Chapel Hill
  Non-Presenting Author