Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental condition that, although traditionally associated with childhood, remains clinically relevant in adulthood. The most recent version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) maintained the same 18 diagnostic symptoms as previous editions, organizing them into two major domains: inattention (IA) and hyperactivity/impulsivity (HY/IM). However, there remains a substantial gap in the literature regarding the structural validity and measurement invariance of this two-dimensional model, especially when considering the different stages of adulthood—most notably, the so-called “emerging adulthood” (18–25 years), a transitional phase marked by specific cognitive, affective, and social challenges.
In this context, the study conducted by Gomez, Watson, and Houghton (2025) offers an important empirical contribution by evaluating the applicability and psychometric robustness of the two-dimensional model of ADHD symptoms in emerging and older adults (26–65 years). Using the Current Symptom Scale (CSS) and confirmatory factor analyses (CFA), the authors tested both the unifactorial and bifactorial structures of the symptoms, as well as the measurement invariance between the two age groups. The results showed that, although both structures presented marginally acceptable fit, the two-factor model (IA and HY/IM) demonstrated better fit in both groups.
Measurement invariance analysis revealed strong evidence for complete invariance—including configural, metric, scalar, and residual variance levels. This indicates that emerging adults and older adults understand and respond to scale items equivalently, which allows direct comparisons of scores observed between groups. This finding is particularly relevant because it reinforces the validity of using the same diagnostic instrument across different phases of adult life (Gomez et al., 2025).
However, it was found that the mean latent scores were significantly higher in the emerging adult group, both for symptoms of inattention and hyperactivity/impulsivity. This finding suggests that, although the structure of symptoms is invariable, the intensity with which they manifest differs between the groups, possibly due to the more intense demands for self-regulation during emerging adulthood – a phase in which the prefrontal cortex is still in the process of maturation, which can exacerbate executive deficits, such as inhibitory control and behavioral organization.
This mismatch between environmental demands and neurocognitive maturity may lead not only to an actual increase in symptoms but also to a subjective perception of greater severity, reflected in self-reported scores. Thus, the higher prevalence of impulsive behaviors and externalizing symptoms in this age group, widely reported in the literature, finds empirical support in this study. A particularly interesting aspect is that, unlike previous studies that suggested a unifactorial structure of symptoms in college students (Flory et al., 2021), this study provides more robust support for the two-dimensional structure of DSM-5 even in this age subgroup, strengthening its clinical applicability.
Factor reliability was considered satisfactory (ω > 0.70), and discriminant validity was considered adequate, despite the relatively high correlation between IA and HY/IM factors. This correlation, although expected given the comorbid nature of ADHD domains, does not compromise the conceptual distinction between them.
From a clinical and theoretical perspective, the study’s findings are extremely relevant. They suggest that the DSM-5 two-factor model is not only applicable but also offers consistent diagnostic validity for the assessment of ADHD in emerging adults—a group often neglected in population and clinical studies. Furthermore, the demonstration of measurement invariance reinforces the model’s usefulness in comparative and longitudinal contexts, such as cohort studies or pre- and post-intervention assessments.
In summary, this study fills a critical gap in the literature by psychometrically validating the DSM-5 symptom model for ADHD across different stages of adulthood, with a focus on the emerging population. Although methodological limitations should be considered—such as the use of a community sample without a confirmed clinical diagnosis—the results provide a solid foundation for future research and for the improvement of diagnostic protocols that are more sensitive to the nuances of adult development.
Reference:
GOMEZ, R.; WATSON, S.; HOUGHTON, S. Psychometric properties of the DSM-5 ADHD two-factor model in emerging and older adults. Academia Mental Health and Well-Being, v. 2, 2025. DOI: https://doi.org/10.20935/MHealthWellB7481.
