A large body of work has investigated the association between birth weight and ADHD and has resulted in mixed findings with regard to the direction and magnitude of this association. Despite the vast amount of research on this topic, a comprehensive and systematic quantification of the association between birth weight and ADHD has yet to be undertaken. A meta-analysis of 88 unique studies (N = 4,645,482) was conducted to quantify the overall effect size of birth weight on ADHD symptoms. Several variables were examined as moderators that may contribute to systematic variation in effect sizes. Overall, birth weight was found to have a small, but significant, association with ADHD symptoms such that individuals born at lower birth weights manifested greater symptoms of ADHD (r = -0.15). Sample type, mean birth weight of the sample, geographic region, the informant of ADHD symptoms, ADHD symptom measurement method, and race were all found to contribute significantly to heterogeneity in effect sizes. Notably, several early life risk factors previously found to be associated with both ADHD and birth weight, gestational age and prenatal smoking exposure, were not found to contribute to heterogeneity in effect sizes. The findings of the current analyses align with the growing recognition that early life adversity contributes to neurodevelopmental difficulties, and the findings highlight the importance of a better understanding of the mechanisms underlying the association between early life risk factors and adverse neurodevelopmental sequela, such as that observed in ADHD.

Adults with attention-deficit/hyperactivity disorder (ADHD) exhibit variable impairments on executive function (EF) tasks. Due to this variability, ratings of EF (rather than tasks) have been proposed as an alternative method that better captures symptom severity and impairment among adults with ADHD. However, few studies have jointly examined performance across multiple neuropsychological domains and EF ratings as predictors of severity and impairment among adults with ADHD. Adults (N = 273) ages 18-38 years (M = 22.6 years, 55.3% male, 62.2% with ADHD) completed a comprehensive diagnostic and neurocognitive assessment, which included self and informant ratings of ADHD symptom severity and EF and tasks of arousal/activation, response inhibition, set shifting, interference control, and working memory. Hierarchical linear regression models indicated that tasks of arousal/activation and response inhibition uniquely predicted ADHD symptom dimensions and related impairments. Over and above EF task performance, EF ratings of time management significantly predicted increased inattention (β = .209, p < .001, ΔR² = 3.9%), whereas ratings of restraint predicted increased hyperactivity/impulsivity (β = .259, p < .001, ΔR² = 6.4%). Furthermore, EF ratings of time management, restraint, and emotion regulation incrementally accounted for variance in relationship, professional, and daily living impairments over and above EF task performance (ΔR² range = 1.7-7.7%). Results may help refine neurobiological theories and assessment of adult ADHD.

Attention-deficit hyperactivity disorder (ADHD) persists into adulthood in over 50% of cases, although its associated symptom profiles, comorbid problems, and neuropsychological deficits change substantially across development. Sluggish cognitive tempo (SCT) symptoms may contribute to associations between ADHD and comorbid problems and may partially explain the substantial heterogeneity observed in its correlates. 349 adults aged 18–38 years (M = 23.2, SD = 4.5, 54.7% male, 61.03% with ADHD) completed a multi-informant diagnostic procedure and a comprehensive neuropsychological battery. Adults with ADHD (n = 213) were retained for analyses. Latent class analyses (LCA) revealed three profiles of SCT symptoms among those with ADHD, which we classified as minimal, moderate, or severe SCT. Multiple analysis of covariance (MANCOVA) revealed significant differences among these profiles, which remained when controlling for persistence of ADHD symptoms and sex. In general, adults with ADHD combined with SCT symptoms (moderate and severe) had significantly more symptoms of anxiety, depression, and persistent inattention, and had more severe professional and relational impairment compared to ADHD adults without SCT. Compared to those with moderate or minimal SCT symptoms, the severe SCT group had the most symptoms of depression and internalizing disorders, and the most impairment in the domain of daily responsibility. No significant differences based on externalizing symptoms emerged when controlling for sex and persistence of inattention symptoms, suggesting the moderate and severe SCT groups do not simply reflect more symptoms. Moreover, follow-up mediation analyses revealed that SCT might at least partially explain the heterogeneity in ADHD. Findings have implications for refinement of etiological conceptualization, assessment methods, and intervention strategies.

Low birth weight (LBW) has consistently been associated with childhood attention- deficit hyperactivity disorder (ADHD), and a similar association has been found for childhood externalizing disorders, such as oppositional defiant disorder (ODD) and conduct disorder (CD), albeit to a lesser degree. Although the association between LBW and these disorders has been robustly replicated, few studies have adequately controlled for confounding variables, such as parental age at birth and prenatal tobacco use, examined the specificity of the risk of LBW for ADHD symptoms, or investigated potential nonlinear (i.e., quadratic) effects of birth weight. Additionally, the extent to which LBW confers risk for these disorders depending on childhood sex has rarely been examined. The current study examined associations between birth weight and ADHD, ODD, and CD symptom dimensions as well as the extent to which such associations are moderated by child sex, while also controlling for confounding variables. Significant interactions between sex and birth weight emerged across all analyses predicting ADHD and externalizing psychopathology, such that associations were stronger in males relative to females. Results remained when controlling for a number of confounds, including parental age, prenatal tobacco use, comorbid psychopathology, as well as other indicators of maternal and child health during the pre- and perinatal period. Both linear and quadratic associations emerged between birth weight and both hyperactivity and CD symptoms, whereas birth weight predicted inattention and ODD symptoms in a linear fashion. Future research should continue to investigate the impact of birth weight on ADHD and externalizing psychopathology, in particular the biological mechanisms underlying this association.

Despite the importance of daily life executive functioning (EF) for college students’ success, few measures exist that have been validated in college students specifically. This study examined the factor structure of the Barkley Deficits in Executive Functioning Scale (BDEFS) in college students. Participants were 1,311 students (ages 18-28 years, 65% female) from five universities in the United States. Additionally, the study examined invariance across sex, age, and attention-deficit/hyperactivity disorder symptoms. Exploratory structural equation modeling provided strong support for the BDEFS five-factor structure though some items had high cross-loadings on multiple factors. Findings generally supported invariance across sex and age; however, loadings, thresholds, and factor means differed based on attention-deficit/hyperactivity disorder symptoms. Stronger support for invariance across sex emerged for a reduced item version that eliminated cross-loading items. Overall, findings provide support for the validity and utility of the BDEFS in college students.