Personality and Attentional Deficits
According to the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; American Psychiatric Association, APA 2013), attention-deficit/hyperactivity disorder (ADHD) is one of the most common childhood disorders. It is generally accepted that establishing links between psychological disorders and personality dimensions are valuable in improving our understanding of their diatheses, cause, progression, prognosis, and treatment. Specific to ADHD, Miller et al. (2008) have argued that it is possible that ADHD and personality are the same constructs viewed through different theoretical lenses. The two major personality models that have featured extensively in ADHD research are variants of the Big Five Model, in particular the five-factor model (FFM; Costa and McCrae 1985; Goldberg 1993), and Cloninger et al.’s (1993) biopsychosocial model. Gomez and Corr (2014) have recently published a meta-analysis of the relationships for the personality dimensions in the FFM with ADHD and its core symptoms of inattention (IA) and hyperactivity/impulsivity (HI). In a subsequent meta-analysis study, Gomez et al. (2017) examined the relationships of the personality dimensions in Cloninger’s model with ADHD. In this article, we provide summaries and implications of the findings for ADHD from both these meta-analysis studies. To facilitate better understanding of the findings, I present first relevant literature on description and theories of ADHD, the FFM, and Cloninger’s model of personality.
Brief Description and Theories of Attention-Deficit/Hyperactivity Disorder (ADHD)
The symptoms, subtypes, and diagnosis proposed for ADHD in DSM-5 (APA 2013) are highly comparable to those in DSM-IV TR (APA 2000) and DSM-IV (APA 1994). All 3 systems list 18 ADHD symptoms under 2 separate groups, namely, IA and HI, with 9 symptoms for each group. The IA symptom group includes behaviors such as distractibility and difficulty focusing on tasks for a sustained period; and the HI symptom group includes behaviors such as fidgeting, excessive talking, and restlessness. DSM-5 indicates that there are three presentations of ADHD: ADHD inattentive presentation (presence of at least six IA symptoms), ADHD hyperactive/impulsivity presentation (presence of at least six HI symptoms), and ADHD combined presentation (presence of at least six IA and six HI symptoms). These presentations were referred to as types in DSM-IV and DSM-IV TR.
ADHD is fairly stable from childhood to adulthood (Biederman et al. 1993; Kessler et al. 2005) and is highly comorbid with both externalizing and internalizing disorders, such as oppositional defiant disorder (ODD), conduct disorder (CD), and mood and anxiety disorders (Spencer et al. 1999). Also, although ADHD is viewed in categorical terms in the major clinical classification systems, there is growing support for it to be viewed dimensionally or as continuous, with the polar ends of this spectrum representing very high and very low amounts of the symptoms (Gomez et al. 2016; Marcus and Barry 2011). Consistent with the dimensional perspective, confirmatory factor analysis (CFA) of the ADHD symptoms in both children and adults has generally provided support for a two-factor model, with separate factors for the IA and HI symptoms (e.g., Gomez et al. 1999, 2003). However, many recent CFA studies have shown more support for a bifactor model (e.g., Gomez et al. in press; Martel et al. 2010). The bifactor model has an ADHD general factor on which all the IA and HI symptoms load and separate orthogonally related specific factors for only the IA and only the HI groups of symptoms. Findings for this model show that much of the variances for the ADHD symptoms are captured by the general factor (Wagner et al. 2016).
Theories of ADHD can be grouped as either single pathway theories, which attempt to explain ADHD without differentiating the IA and HI symptom groups, or dual pathway theories, which differentiate and implicate different processes for the two symptom domains. Dominant among single pathway theories is the response inhibition deficit theory proposed by Barkley (1997) that suggests that a central deficit in response inhibition leads to problems in higher order cognitive processes, which then contribute to responses that manifest as ADHD symptoms. Dual pathways theories suggest that “top-down” control processes, such as deficits in executive functioning and problems with cognitive (effortful) control processes, underlie the IA symptoms, while “bottom-up” control processes, such as deficits in reward responses and problems with motivational (reactive) control processes, underlie the HI symptoms (Martel and Nigg 2006; Nigg et al. 2004; Sonuga-Barke 2003). When the dual pathways theories and the bifactor ADHD models are considered together, it can be speculated that ADHD, in general, is associated with defects in both top-down (regulatory) and bottom-up (reactive) inhibitory control processes.
The FFM of personality comprises the personality dimensions of extraversion, neuroticism (sometimes referred to in terms of its polar opposite end called emotional stability), agreeableness, conscientiousness, and openness to experience (Costa and McCrae 1985). Extraversion refers to being sociable, outgoing, optimistic, and sensation seeking versus being quiet, passive, and careful. Neuroticism refers to the tendency for proneness to unpleasant experiences and maladjustment. Agreeableness refers to the tendency to be agreeable, trustworthy, friendly, and cooperative with others. Conscientiousness refers to the tendency to be well organized, responsible, and task-focused in pursuing goals. Openness to experience refers to the tendency for being imaginative, creative, and interested in cultural and educational experiences. At present there is considerable empirical support for the construct validity, temporal stability, and also cross-cultural relevance for the FFM in children, adolescents, and adults (Costa and McCrae 1985; McCrae et al. 2005).
Cloninger’s Biopsychosocial Model and ADHD
The original formulation by Cloninger (1987) was a tridimensional structure, comprising the temperament dimensions of novelty seeking, harm avoidance, and reward dependence. As the facet of persistence did not closely correlate with its designated reward dependence factor, it was suggested as a fourth temperament dimension. Novelty seeking is the tendency to approach novel situations for rewards and to experience relief from non-punishment. High novelty seeking includes impulsivity, quick-temper, and proneness to breaking rules. Harm avoidance is the tendency to inhibit or avoid responses to aversive cues, such as punishment and non-reward. High harm avoidance is associated with high anticipatory anxiety and fear. Reward dependence is the tendency to maintain responses that have been previously conditioned through rewards. High reward dependence is associated with being sociable and sensitive to social cues. Persistence is the tendency to maintain responses, despite frustration and fatigue. High persistence is associated with persevering and being ambitious.
Cloninger’s current biopsychosocial model of personality also includes three character dimensions (Cloninger et al. 1993). These are self-directedness, cooperation, and self-transcendence. Self-directedness reflects the ability to control, regulate, and adapt one’s behavior to concur with existing situations to achieve one’s goals and values. Cooperation reflects identification with and acceptance of others. Self-transcendence reflects imaginativeness and spirituality.
In Cloninger’s current model, the temperament components relate to innate dispositions based on major brain-behavioral systems of emotion, motivation, and reinforcement, whereas the character components relate largely to environmental factors. The interplay between biological and environmental factors has been implicated in the phenotypic expression, continuity, and changes in the clinical presentation of ADHD (Thapar et al. 2007). This means that Cloninger’s current model of personality may be of special interest for understanding ADHD as it will enable us to acquire a comprehensive understanding of how personality factors, linked to biological and environmental processes, are associated with ADHD.
Summary of the Meta-analysis Study Examining the Relationships of FFM Personality Dimensions with ADHD, IA, and HI
The meta-analysis study by Gomez and Corr (2014) that focused on the FFM was based on 17 data sets, involving 5348 participants. The findings showed that for ADHD, IA, and HI, the effect sizes for the relationships with neuroticism, conscientiousness, and agreeableness were all significant. The effect size for the association of extraversion with HI was significant. All other associations were not significant. All significant associations for ADHD, IA, and HI with neuroticism were positive, whereas all associations with conscientiousness and agreeableness were negative. The extraversion-HI association was positive. For ADHD, the effect sizes for neuroticism and conscientiousness were large, and the effect size for agreeableness was medium, based on cut-off effect size scores proposed by Cohen (1988): <0.20 = negligible, ≥0.20 and <0.50 = small, ≥0.50 and <0.80 = medium, and ≥0.80 = large. For IA, the effect sizes for neuroticism, conscientiousness inhibition, and agreeableness were medium, large, and small, respectively. For HI, the effect sizes for neuroticism, conscientiousness, and agreeableness were small, large, and medium, respectively. The effect size for the association of extraversion with HI was small.
The findings of the meta-analysis also showed that the significant relation for neuroticism with ADHD was moderated by source from where study participants were recruited (clinic vs. community). The effect size was significant, positive, and large for clinic samples, whereas it was significant, positive, and medium for community samples. All significant relations for conscientiousness and agreeableness with ADHD, IA, and HI were not moderated by either source or age group (children/adolescents vs. adults). Also, the significant relation between extraversion and HI was moderated by source and age group. For the moderation involving age group, the effect size was significant, positive, and medium for children/adolescents, whereas it was not significant, and negligible for adults. For the moderation involving source, the effect size was significant, positive, and small for clinic samples, whereas it was not significant, positive, and negligible for community samples.
Summary of the Meta-analysis Study Examining the Relationships of Cloninger’s Biopsychosocial Model with ADHD, IA, and HI
The meta-analysis study by Gomez et al. (2017) that focused on Cloninger’s model was based on 20 data sets, involving 2984 participants. Findings were reported for only ADHD, and not for IA and HI due to very few studies that explored these symptom dimensions. The findings showed that with the exception of self-transcendence, the effect sizes for all the other dimensions in Cloninger’s model with ADHD were significant. The associations for ADHD with novelty seeking and harm avoidance were positive, whereas the associations with reward dependence, persistence, self-directedness, and cooperation were negative. The effect sizes for novelty seeking and self-directedness were both large, and the effect sizes for persistence and cooperation were medium. Although the effect size for persistence fell within the medium effect size range, it was very close to the lower end of the range for large effect size. The effect sizes for harm avoidance and reward dependence were small. Additionally, with the exception of reward dependence, all other effect sizes showed heterogeneity.
The results for the moderation analyses by age group (children/adolescents vs. adults) and source (clinic vs. community) showed that the effect sizes for novelty seeking, self-directedness, cooperation, reward dependence, and self-transcendence were not moderated by age group. The effect sizes for harm avoidance and persistence were moderated by age group. The effect size for novelty seeking was significant, positive, and medium for the adult sample, while it was not significant for the child/adolescent sample. For persistence, the effect size was significant, negative, and small for adults, while it was significant, negative, and large for children/adolescents. Also, the effect sizes for novelty seeking, harm avoidance, self-directedness, cooperation, reward dependence, and self-transcendence were not moderated by source, whereas the effect size for persistence was moderated by source. The effect size for persistence was significant, negative, and large for clinic samples, while it was significant, negative, and small for the community samples.
Implication for Theories of ADHD
Cloninger’s dimension of novelty seeking reflects the tendency to approach novel situations for rewards and to experience relief from non-punishment, while self-directedness reflects the ability to control, regulate, and adapt one’s behavior to concur with existing situations to achieve one’s goals and values. Persistence reflects the tendency to maintain responses even in the face of frustration and fatigue. Thus, novelty seeking, self-directedness, and persistence are related to control processes, with novelty seeking reflecting a reactive bottom-up control process and persistence and self-directedness reflecting top-down control processes. In the FFM, conscientiousness and agreeableness are the primarily personality markers for top-down cognitive control processes and bottom-up reactive control processes, respectively (Martel and Nigg 2006; Nigg et al. 2004). As will be recalled, Gomez and Corr (2014) found associations for ADHD with personality dimensions of conscientiousness and agreeableness. Taken together, these findings indicate that ADHD is related to impulsivity and response inhibition deficits associated with both poor regulatory (bottom-up) and reactive (top-down) control processes (Martel and Nigg 2006; Nigg et al. 2004; Sonuga-Barke 2003).
As Gomez and Corr (2014) examined the differential associations of the FFM dimensions with IA and HI, their findings allowed for exploring how the regulatory and reactive control processes are differentially associated with IA and HI. Since conscientiousness and agreeableness were associated negatively with both IA and HI, Gomez and Corr suggested that deficits in both top-down and bottom-up control processes are associated with IA and HI. However as their findings showed large associations for conscientiousness with IA and HI, with the associations generally being stronger for IA than HI, small associations for agreeableness with IA, and medium associations with HI, Gomez and Corr argued that while both top-down and bottom-up deficits are associated with IA and HI, compared to HI, IA will be associated with more deficits in top-down control processes, whereas, compared to IA, HI will be associated with more deficits in bottom-up control processes. This view of relative differences is consistent with the well-established findings that IA and HI are highly correlated and also that top-down and bottom-up control processes are also highly correlated (Martel et al. 2009, 2010).
Implications for Understanding the Different ADHD Types or Presentations
The findings reported by Gomez and Corr (2014) have implications for understanding the different ADHD types or presentations. As conscientiousness and agreeableness were associated negatively with both IA and HI, the findings raise the possibility that deficits in both top-down and bottom-up control processes will be associated with ADHD inattentive and ADHD hyperactive/impulsive types or presentations, respectively. However since the findings showed that IA had larger associations with conscientiousness and small associations with agreeableness and HI had medium associations with conscientiousness and agreeableness, it can be speculated that the ADHD inattentive type/presentation will be associated with more deficits in top-down control processes, whereas the ADHD hyperactive/impulsive type/presentation will be associated with more deficits in bottom-up control processes. In addition, as negative emotionality was linked to both IA and HI but stronger with IA than with HI, it can be speculated that while both these types/presentations of ADHD will be associated with hyper-reactivity to environmental demands and stress, the inattentive type/presentation can be expected to be more reactive to environmental demands and stress and therefore more susceptible to interference with attention control than the hyperactive/impulsive type/presentation.
As the ADHD combined type/presentation has high levels of both IA and HI symptoms, it can be speculated that this ADHD type would have the characteristics of both the ADHD inattention and hyperactive/impulsivity types/presentations. This means that the combined type/presentation can be speculated to have deficits in top-down and bottom-up control processes that are comparable to the ADHD inattentive type/presentation and ADHD hyperactive/impulsive type/presentation, respectively. In addition, it would be associated with hyper-reactivity to environmental demands and stress that are comparable to the inattentive type/presentation.
Possible Underlying Processes for the Personality-ADHD Link
The findings in the meta-analysis reported by Gomez et al. (2017) have implications for understanding the biological and non-biological factors involved in ADHD. The ADHD literature has started to examine the roles played by biological and non-biological factors in its course and expression (Psychogiou et al. 2008; Thapar et al. 2007). Thapar et al. (2007) have emphasized that there is no single cause for ADHD, and the phenotypic expression, continuity, and changes in clinical presentation of ADHD are influenced directly and interactively by biological, psychosocial, environmental, and genetic factors. Although personality is often associated with biological factors, it is also conceptualized to be influenced by social learning (Buss and Plomin 1975; Halverson et al. 1994). In Cloninger’s model (1993), the temperament dimensions of novelty seeking, harm avoidance, reward dependence, and persistence are assumed to be strongly heritable, while the character dimensions of self-directedness, cooperation, and self-transcendence (fantasy and spirituality in children) are assumed to be influenced by social learning. Thus, the findings in the Gomez et al. (2017) study can be taken to support the contribution and interplay of biological and non-biological factors, at least in the phenotypic expression of ADHD.
Underlying Process for the Relationships Between Personality and ADHD
The findings in the Gomez and Corr (2014) study suggest that the underlying processes for the relationships between personality and ADHD are as described for the spectrum model proposed by Tackett (2006). This model suggests that personality traits and psychological disorder lie on a continuum and that they are different manifestations of the same system. This model would predict that as the severity of a disorder increases there will be proportional increase in the link between personality and the disorder. Thus, findings of stronger associations for ADHD with the personality dimensions in clinic samples, compared to community samples, can be taken as being consistent with the predictions from the spectrum model. Support for this view has also come more directly in a recent study (Martel et al. 2014) that reported that although personality variables were associated with ADHD symptoms at 3 years (consistent with the spectrum model), the personality variables at age 3 years did not predict ADHD symptoms at 5 years of age (inconsistent with the vulnerability model).
The agreeableness dimension is linked to poor organization, efficiency, diligence, attention to task, responsibility, compliance, and self-control; and conscientiousness is linked to motivational control processes. Also, the dimensions of novelty seeking, self-directedness, and persistence together can be linked to poor organization, efficiency, diligence, attention to task, responsibility, compliance, self-control, and motivation. Thus, based on the findings in the Gomez and Corr (2014) and Gomez et al. (2017) meta-analysis studies, it could be argued that individuals suffering from ADHD might demonstrate relatively more severe ADHD behaviors when they are exposed to environments that place additional demands on such processes. The management implications are that the training of individuals with ADHD needs to follow a successive approximation approach, which allows the gradual development of these processes. Also as self-directedness, being a character dimensions, will influence the temperament dimensions, it can be speculated that interventions targeting the development of attention, cognitive, and self-control skills through social learning would be a useful treatment option. To date there has been little research on either the role of social learning in the development and progression of ADHD or the impact of social self-control training in the management of ADHD. These are clearly important areas for future research.
Conclusions and a Personality Model of ADHD
Major findings in the Gomez and Corr (2014) study were that there were significant but different levels of associations for ADHD, IA, and HI with neuroticism, conscientiousness, and agreeableness and that some of the associations were moderated by age (children/adolescents vs. adults) and source (whether participants were recruited from clinics or from communities). The findings in the Gomez et al. (2017) showed large or close to large effect sizes for novelty seeking, self-directedness, and persistence. The effect size for cooperation was medium. The effect sizes for both harm avoidance and reward dependence were small. The results for the moderation analyses showed that harm avoidance and persistence were moderated by age group. Further, the source of the sample, also, moderated the effect size for persistence. The confluence of findings for the associations made for the various personality dimensions with IA and HI leads to the strong inference that some personality variables are closely intertwined with ADHD. When these findings are considered collectively, they suggest that although top-down cognitive control processes are more problematic than bottom-up control processes in both the IA and HI symptom groups, the distinction between IA and HI may be related to the relative degree of deficits in top-down cognitive control processes and bottom-up control processes. The findings suggest that compared to HI, IA has relatively more deficits for top-down control processes and relative less deficits for bottom-up control processes. Furthermore, compared to IA, HI has relatively more deficits for bottom-up control processes and relative fewer deficits for top-down control processes.
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