Executive functioning and olfactory identification in young adults with attention deficit-hyperactivity disorder

Unique Patterns of Eye Movements Characterizing Inattentive Reading in ADHD

OBJECTIVE

We aimed to identify unique patterns of eye-movements measures reflecting inattentive reading among adults with and without ADHD.

METHOD & RESULTS

We recorded eye-movements during uninterrupted text reading of typically developed (TD) and ADHD adults. First, we found significantly longer reading time for the ADHD group than the TD group. Further, we detected cases in which words were reread more than twice and found that such occasions were much more frequent in participants with ADHD than in TD participants. Moreover, we discovered that the first reading pass of these words was less sensitive to the length of the word than the first pass of words read only once, indicating a less meaningful reading.

CONCLUSION

We propose that high rate of words that were reread is a correlate of inattentive reading which is more pronounced among ADHD readers. Implications of the findings in the context of reading comprehension are discussed.

Deficits in olfactory system neurogenesis in neurodevelopmental disorders

The role of neurogenesis in neurodevelopmental disorders (NDDs) merits much attention. The complex process by which stem cells produce daughter cells that in turn differentiate into neurons, migrate various distances, and form synaptic connections that are then refined by neuronal activity or experience is integral to the development of the nervous system. Given the continued postnatal neurogenesis that occurs in the mammalian olfactory system, it provides an ideal model for understanding how disruptions in distinct stages of neurogenesis contribute to the pathophysiology of various NDDs. This review summarizes and discusses what is currently known about the disruption of neurogenesis within the olfactory system as it pertains to attention-deficit/hyperactivity disorder, autism spectrum disorder, Down syndrome, Fragile X syndrome, and Rett syndrome. Studies included in this review used either human subjects, mouse models, or Drosophila models, and lay a compelling foundation for continued investigation of NDDs by utilizing the olfactory system.

Young Adult ADHD Symptoms in the General Population and Neurocognitive Impairment

OBJECTIVE

Neurocognitive impairments are associated with child and adult ADHD in clinical settings. However, it is unknown whether adult ADHD symptoms in the general population are associated with the same pattern of cognitive impairment. We examined this using a prospective, population-based cohort spanning birth to age 25 years.

METHODS

We examined associations between self-reported adult ADHD symptoms and cognitive task performance (attention and response inhibition) in adulthood and childhood.

RESULTS

Self-rated ADHD symptoms at age 25 were associated with poorer performance in age 25 cognitive tasks capturing ADHD-related functioning (attention B = -0.03, 95% CI [0.05, -0.01], p = .005; response inhibition B = -0.03, 95% CI [-0.05, -0.01], p = .002).

CONCLUSIONS

Neurocognitive impairments linked to adult ADHD symptoms in the general population, are similar to those found in people with childhood ADHD symptoms and are consistent with findings in adult ADHD clinical samples.

The Effect of Methylphenidate Treatment on Olfactory Function in Children and Adolescents With ADHD

OBJECTIVE

This study aimed to research whether there is an olfactory disorder in ADHD, and if so, what is the effect of methylphenidate on this condition.

METHOD

This is a cross-sectional study aiming to evaluate olfactory threshold, identification, discrimination and threshold, discrimination, and identification (TDI) scores in 109 children and adolescents, 33 of whom have ADHD without medication, 29 with ADHD with medication and 47 control groups.

RESULT

In the post hoc tests, the mean odor discrimination test, the mean odor identification test, and the mean TDI scores of the unmedicated ADHD group were significantly lower than those of the other two groups, and that the mean odor threshold test scores of the medicated ADHD group were significantly lower than those of the control and unmedicated groups.

CONCLUSION

Olfactory function could be a useful tool to monitor treatment effects and may be a promising candidate as a biomarker in ADHD.

Does comorbid depression impact executive functioning (EF) in adults diagnosed with ADHD?: a comparison of EF across diagnoses in clinically-referred individuals

INTRODUCTION

Executive functioning (EF) is a salient factor in both ADHD as well as depressive disorders. However, sparse literature has examined whether depression severity impacts EF concurrently among adults with ADHD. The goal of this study was to examine differences in EF between adult patients diagnosed with ADHD and those diagnosed with a non-ADHD primary psychopathological condition, as a function of both ADHD presentation and depression severity in a diverse clinical sample.

METHOD

This crosssectional study included 404 adult patients clinically referred for neuropsychological evaluation to assist with differential diagnosis and/or treatment planning related to known or suspected ADHD. Various EF tasks and a measure of depression severity were administered. One-way MANOVA analyses were conducted to compare EF performance between individuals diagnosed with ADHD or a non-ADHD primary psychopathological condition, with additional analyses examining group differences based on ADHD presentation and depression severity. Regression analyses also examined the potential contribution of depression severity to each EF measure within each group.

RESULTS

No significant EF performance differences were found when comparing individuals diagnosed with ADHD and those with a non-ADHD primary psychopathological condition, nor based on ADHD presentation. When comparing across groups using cut-offs for high or low depression, only one EF measure showed significant differences between groups. Further, depression severity generally did not predict reduced EF performances with the exception of verbal fluency and working memory performances in select groups.

CONCLUSIONS

This study demonstrated that individuals with ADHD generally perform comparably on EF measures regardless of the presence or absence of comorbid depression. These results suggest further examination of EF deficits when they emerge for adults with ADHD, especially beyond comorbid depression severity.

Attentive-executive functioning and compensatory strategies in adult ADHD: A retrospective case series study

Background

Adults with ADHD exhibit a neuropsychological profile that may present deficits in many cognitive domains, particularly attention and executive functions (EFs). However, some authors do not consider executive disfunction as an important part of the clinical profile of the syndrome; this could be related to the use of inappropriate neuropsychological tests, probably not adapted and not sufficiently ecological. Moreover, new data are required on specific correlation of attentive-executive symptoms with socio-demographic factors. Therefore, the aim of this study is to analyze the neuropsychological performance of a group of adults with ADHD, also evaluating the influence of gender, age and education level.

Methods

We retrospectively collected health-related personal data of 40 adult ADHD patients, clinically diagnosed and evaluated via a battery of 4 neuropsychological tests and 1 self-administered questionnaire. Gender, age and years of education differences were assessed.

Results

Attention and EFs deficits have been highlighted mainly on the d2-R and 5-point neuropsychological tests, which therefore seem to be more sensitive in measuring the attention-executive dysfunction in an adult ADHD population, than TAP Go/No-go and ROCFT. ADHD patients also manifested subjective behavioral impulsivity disorders on BIS-11. There were no statistically significant gender differences in cognitive performance. On the contrary, younger patients performed worse on subscales TAP Go/No-go errors and 5-points number of drawings, while participants with a higher education level performed better on subscales d2-R speed of execution and d2-R errors. This supports a reduction in the number of errors and the execution time as a function of older age and a higher level of education. Finally, patients with higher education also self-reported greater impulsivity in planning.

Conclusion

Our preliminary findings suggest that adult ADHD is not a lifelong stable disorder, but it may change over time. Moreover, attention-executive deficits may be influenced and partially counterbalanced by experience (i.e., advancing age) and a higher level of education. This could underlie the development of specific psycho-behavioral and cognitive compensatory strategies. The use of self-administered questionnaires is therefore recommended to highlight attentional and executive difficulties that may not result in neuropsychological tests.

Cognitive mechanisms underlying depressive disorders in ADHD: A systematic review

The risk for major depressive disorder (MDD) is considerably increased in young adults with attention-deficit/hyperactivity disorder (ADHD) but underlying mechanisms are poorly understood. This review explores ADHD-specific neurocognitive impairments as possible underlying mechanisms for ADHD-depression comorbidity. Two systematic literature searches were conducted in EBSCOhost, PubMED, and Cochrane Reviews databases according to PRISMA guidelines. The first search identified 18 meta-analyses of cross-sectional and longitudinal studies on cognitive dysfunctions in MDD across the lifespan. The second search identified six original studies on reaction time variability in MDD. During acute depression, children and adults showed cognitive deficits that overlapped with some of the ADHD-related impairments. Findings from remitted patients, high-risk individuals, and few prospective studies suggest that a subset of these shared impairments, specifically executive dysfunctions (selective attention, verbal fluency, working memory) and long-term memory problems, are candidate pre-existing risk markers of depression. We discuss if and how these specific neurocognitive mechanisms may mediate developmental pathways from ADHD to depression. If replicated by longitudinal studies, these findings may guide future prevention strategies.

Creativity in ADHD: Goal-Directed Motivation and Domain Specificity

Objective: This research aimed to provide explanations for the inconsistent findings regarding creativity in ADHD. Method: In Study 1, we assessed real-world creative achievements and intrinsic motivation during idea generation in adults with ADHD and compared these with controls. In Study 2, we manipulated competition during idea generation to investigate effects on idea originality in adults with ADHD versus controls, and assessed creativity in specific domains. Results: Adults with ADHD reported more real-world creative achievements. We did not observe differences in intrinsic motivation during idea generation between groups, but adults with ADHD generated more original ideas when competing for a bonus. Moreover, adults with ADHD rated themselves as more creative in specific creative domains. Conclusion: Our findings suggest that goal-directed motivation may drive the enhanced real-world creative achievements of people with ADHD. Moreover, people with ADHD may selectively engage and excel in creative domains that fit their skills and preferences.

Deconstructing Cognitive Heterogeneity in Puerto Rican Spanish-Speaking Children With ADHD

OBJECTIVE

There is limited understanding of the cognitive profiles of Spanish-speaking children with Attention-Deficit/Hyperactivity Disorder (ADHD). The current study investigated the cognitive cluster profiles of Puerto Rican Spanish-speaking children with ADHD using the Wechsler Intelligence Scales for Children-Fourth Edition Spanish (WISC-IV Spanish) Index scores and examined the association between cognitive cluster profiles with other potentially relevant factors.

METHOD

Hierarchical cluster analysis was used to identify WISC-IV clusters in a sample of 165 Puerto Rican children who had a primary diagnosis of ADHD. To examine the validity of the ADHD clusters, analysis of variances and chi-square analyses were conducted to compare the clusters across sociodemographics (e.g., age and education), type of ADHD diagnosis (ADHD subtype, Learning Disorder comorbidity), and academic achievement.

RESULTS

Clusters were differentiated by level and pattern of performance. A five-cluster solution was identified as optimal that included (C1) multiple cognitive deficits, (C2) processing speed deficits, (C3) generally average performance, (C4) perceptual reasoning strengths, and (C5) working memory deficits. Among the five clusters, the profile with multiple cognitive deficits was characterized by poorer performance on the four WISC-IV Spanish Indexes and was associated with adverse sociodemographic characteristics.

CONCLUSIONS

Results illustrate that there is substantial heterogeneity in cognitive abilities of Puerto Rican Spanish-speaking children with ADHD, and this heterogeneity is associated with a number of relevant outcomes.

The Utility of the CPT in the Diagnosis of ADHD in Individuals with Substance Abuse: A Systematic Review

BACKGROUND

Early identification of attention-deficit/hyperactivity disorder (ADHD) in individuals with substance use disorders (SUD) is important because ADHD has an adverse effect on the development and course of SUD. Given the limited validity of self-report measures of ADHD in individuals with SUD, it is important to investigate the utility of the continuous performance test (CPT) in classifying ADHD in adults with SUD.

OBJECTIVE

This review aims to examine the quantitative similarities and differences in CPT performance of adults with ADHD, SUD, and their comorbidity to determine if a distinct neurocognitive profile exists for each.

METHOD

A systematic review of CPT studies that included patients with the comorbidity of ADHD and SUD and a comparison group of one of the disorders alone was conducted. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used.

RESULTS

Eight studies were identified with sample sizes ranging from n = 17 to n = 386. The comorbidity of ADHD and SUD was, mostly, not associated with higher rates of commission and omission errors than either disorder alone. However, the comorbidity of ADHD and SUD was more likely to be associated with increased deficits in response time variability compared with individuals with ADHD alone.

CONCLUSIONS

This review highlights the shortage of large-scale CPT research involving patients with ADHD and SUD. The CPT might be sensitive to attentional deficits, but it lacks specificity for the classification of adult ADHD, SUD, or their comorbidity, and the CPT is thus not useful in discriminating comorbid ADHD and SUD from either disorder alone. Future CPT research should explore whether specific attentional deficits account for the development and persistence of SUD. Such research should also reach beyond traditional CPT measures and include other cognitive and behavioral deficits that were associated with ADHD, such as distractibility and hyperactivity.

Reduced hemispheric asymmetry of brain anatomical networks in attention deficit hyperactivity disorder

Despite many studies reporting a variety of alterations in brain networks in patients with attention deficit hyperactivity disorder (ADHD), alterations in hemispheric anatomical networks are still unclear. In this study, we investigated topology alterations in hemispheric white matter in patients with ADHD and the relationship between these alterations and clinical features of the illness. Weighted hemispheric brain anatomical networks were first constructed for each of 40 right-handed patients with ADHD and 53 matched normal controls. Then, graph theoretical approaches were utilized to compute hemispheric topological properties. The small-world property was preserved in the hemispheric network. Furthermore, a significant group-by-hemisphere interaction was revealed in global efficiency, local efficiency and characteristic path length, attributed to the significantly reduced hemispheric asymmetry of global and local integration in patients with ADHD compared with normal controls. Specifically, reduced asymmetric regional efficiency was found in three regions. Finally, we found that the abnormal asymmetry of hemispheric brain anatomical network topology and regional efficiency were both associated with clinical features (the Adult ADHD Self-Report Scale and Wechsler Adult Intelligence Scale) in patients. Our findings provide new insights into the lateralized nature of hemispheric dysconnectivity and highlight the potential for using brain network measures of hemispheric asymmetry as neural biomarkers for ADHD and its clinical features.

DSM-5 and Other Symptom Thresholds for ADHD: Which Is the Best Predictor of Impairment in College Students?

OBJECTIVE

Approximately 5% of adults have ADHD. Despite recommendations regarding the diagnosis of emerging adults, there is not a strong consensus regarding the ideal method for diagnosing ADHD in both emerging and mature adults. We were interested in determining whether a threshold of four, five, or six ADHD symptoms would be associated with significantly different levels of functional impairment and be more or less indicative of a potential ADHD diagnosis.

METHOD

We examined the relation between functional impairment and these ADHD symptom thresholds in 2,577 college students.

RESULTS

Our findings suggest that none of these symptom thresholds are differentially better at predicting functional impairment.

CONCLUSION

The Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5) threshold of five symptoms for ages 17 years and older is not necessarily predictive of ADHD-related impairment in college students and may not be preferable to other thresholds. Options for resolving this diagnostic dilemma are discussed.

Neuropsychological Performance Patterns of Adult ADHD Subtypes

Objective: Neuropsychological performance patterns associated with adult ADHD subtypes are unknown. The aim of the current systematic review was to identify and synthesize available literature regarding neuropsychological performance associated with adult ADHD subtypes. Method: Searches were completed using the databases PsycINFO and PubMed for studies published before March 2017 addressing adult ADHD subtypes and neuropsychological performance. Data characterizing the neuropsychological tests utilized in each study were obtained and sorted into eight domains. To summarize the results of all comparisons (ADHD subtype compared with control, or to each other), we counted the proportion of tests within each domain with significant group differences. Results/Conclusion: We deemed four domains informative in differentiating ADHD subtypes from controls. Of these, memory was the only domain that held promise in distinguishing ADHD-Inattentive and ADHD-Combined. Limitations of the available literature are highlighted and recommendations for future research are provided.

Hyperactive Child Syndrome and Estimated Life Expectancy at Young Adult Follow-Up: The Role of ADHD Persistence and Other Potential Predictors

OBJECTIVE

We examined if ADHD Combined Type or Presentation (ADHD-C) reduced estimated life expectancy (ELE) at young adulthood and if the persistence of ADHD to adulthood further adversely affected ELE.

METHOD

A young adult follow-up of 131 hyperactive and 71 control cases was used to derive 14 variables that were entered into a life expectancy calculator to generate ELE scores. Both ratings of executive function (EF) in everyday life and tests of EF and IQ were measured along with comorbid psychopathologies.

RESULTS

Childhood ADHD-C was associated with a 9.5-year reduction in healthy ELE, and a 8.4-year reduction in total ELE relative to control children by adulthood. The persistence of ADHD to adulthood was linked to a 12.7-year reduction in ELE. Several background traits accounted for more than 39% of variation in ELE.

CONCLUSION

Childhood ADHD-C predicts a significantly reduced ELE by adulthood, which is further reduced by the persistence of ADHD to adult follow-up.

Behavioral and Cognitive Impacts of Mindfulness-Based Interventions on Adults with Attention-Deficit Hyperactivity Disorder: A Systematic Review

Mindfulness-based interventions (MBIs) are becoming increasingly popular as treatments for physical and psychological problems. Recently, several studies have suggested that MBIs may also be effective in reducing symptoms of attention-deficit hyperactivity disorder (ADHD). Most studies have examined the effectiveness in children, but there are now a sufficient number of individual treatment trials to consider a systematic review in adults. Majority of existing systematic reviews and meta-analyses only consider ADHD symptoms as an outcome, and most of them do not fully report potential biases of included studies, thus limiting considerably their conclusions. This is an important facet because some studies could be found ineligible to be included in future analysis due to their low quality. In this systematic review, we followed the PRISMA/PICO criteria and we thoroughly assessed the risks of bias for each of the selected studies according to Cochrane guidelines. We searched the available literature concerning MBIs in adult participants with ADHD using PsycINFO, PubMed, Scopus, and ERIC databases. In total, 13 studies conducted with 753 adults (mean age of 35.1 years) were identified as eligible. Potential moderators such as participants' age, ADHD subtypes, medication status, comorbidity, intervention length, mindfulness techniques, homework amount, and training of therapists were carefully described. Aside from measuring the symptoms of ADHD, outcome measures were categorized into executive/cognitive functioning, emotional disturbances, quality of life, mindfulness, and grade point average at school. According to presented descriptive results, all the studies (100%) showed improvement of ADHD symptoms. In addition, mindfulness meditation training improves some aspects of executive function and emotion dysregulation. Although these are promising findings to support treatment efficacy of MBIs for ADHD, various biases such as absence of randomization and lack of a control group may affect the actual clinical value and implications of the studies. Moreover, the relatively low quality of selection and performance criteria in several studies, as well as relatively high attrition bias across studies, call for caution before considering conducting further analysis.

Acute Effects of Aerobic Exercise on Executive Function and Attention in Adult Patients With ADHD

Aerobic exercise can improve cognitive functions in healthy individuals and in various clinical groups, which might be particularly relevant for patients with ADHD. This study investigated the effects of a single bout of aerobic exercise on attention and executive functions in adult patients with ADHD, including functional MRI to examine the underlying neural mechanisms. On two different days, 23 adult patients with ADHD and 23 matched healthy controls performed in a flanker task, while functional MR images were collected, following 30 min of continuous stationary cycling with moderate intensity as well as after a control condition (watching a movie). Behavioral performance and brain activation were tested for differences between groups and conditions and for interactions to investigate whether exercise improves executive function to a greater extent in patients compared to healthy controls. Exercise significantly improved reaction times in congruent and incongruent trials of the flanker task in patients with ADHD but not in healthy controls. We found no changes in brain activation between the two conditions for either group. However, a subgroup analysis of ADHD patients with a higher degree of cardiorespiratory fitness revealed decreased activation in premotor areas during congruent trials and in premotor and medial frontal cortex during incongruent trials in the exercise compared to the control condition. Our results indicate exercise-induced improvements in attention and processing speed in patients with ADHD, demonstrating that adult patients with ADHD may benefit from an acute bout of exercise. These findings could be of high relevance for developing alternative treatment approaches for ADHD. In addition, results of the current study contribute to elucidate the neurophysiological mechanisms underlying the beneficial effects of exercise on cognition and to better understand the role of cardiorespiratory fitness on these effects.

Specificity of executive functioning and processing speed problems in common psychopathology

OBJECTIVE

Interest continues in neuropsychological measures as cross-disorder intermediate phenotypes in understanding psychopathology. A central question concerns their specificity versus generalizability to particular forms of psychopathology, particularly for executive functioning (EF) and response speed. Three conceptual models examining these relationships were tested to clarify this picture at different levels in the diagnostic hierarchy.

METHOD

Participants (total n = 641, age 18-60) yielded complete structured diagnostic interviews and a neuropsychological test battery comprising measures of executive function, processing speed, and IQ. Repeated measures multivariate analysis of variance, linear regression, and structural equation modeling (SEM) were used to test (a) a specificity model, which proposes that individual disorders are associated with component EF processes and speed; (b) a severity model, which proposes that the total number of comorbid disorders explain poor EF and/or slow speed; and (c) a higher-order dimensional model, which proposes that internalizing versus externalizing disorders are differentially related to EF or speed.

RESULTS

EF effects were best explained by a specificity model, with distinct aspects of EF related to attention deficit hyperactivity disorder versus antisocial substance use disorders. Speed, on the other hand, emerged as a general indicator of externalizing psychopathology in the dimensional model, as well as overall severity of psychopathology in the severity model.

CONCLUSIONS

Granular approaches are likely to be most productive for linking EF to psychopathology, whereas response speed has underused potential as an endophenotype for psychopathology liability. Results are discussed in terms of an integrated conceptualization of neuropsychological processes and putative neural systems involved in general and specific aspects of psychopathology. (PsycINFO Database Record

Perception in attention deficit hyperactivity disorder

A large body of research demonstrated that individuals with attention deficit hyperactivity disorder (ADHD) suffer from various neuropsychological deficits. In contrast, less is known and only divergent evidence exists on perceptual functions of individuals with ADHD. This is problematic as neuropsychological and perceptual functions are closely interrelated and are often difficult to disentangle in behavioral assessments. This study presents the conduct and results of a systematic literature review on perceptual functions in children and adults with ADHD. This review considers studies using psychophysical methods (objective measurements) and self- and informant reports (subjective measurements). Results indicate that individuals with ADHD have altered perceptual functions in various domains as compared to typically developing individuals. Increased perceptual functions in individuals with ADHD were found with regard to olfactory detection thresholds, whereas reduced perceptual functions were evident for aspects of visual and speech perception. Moreover, individuals with ADHD were found to experience discomfort to sensory stimuli at a lower level than typically developing individuals. Alterations of perceptual functions in individuals with ADHD were shown to be moderated by various factors, such as pharmacological treatment, cognitive functions, and symptom severity. We conclude by giving implications for daily life functioning and clinical practice.

Cognitive profiles of adults with high-functioning autism spectrum disorder and those with attention-deficit/hyperactivity disorder based on the WAIS-III

The cognitive profile differences between adult patients with autism spectrum disorder (ASD) and those with attention-deficit/hyperactivity disorder (ADHD) are not well characterized. We examined the cognitive profiles of adults having either ASD (n=120) or ADHD (n=76) with no intellectual disabilities (IQ≥70) using the Wechsler Intelligence Scale III (WAIS-III). Verbal Intelligence (VIQ) - Performance Intelligence (PIQ) difference discrepancies were detected between the two groups. Information subtest scores of the Verbal Comprehension index and Arithmetic and Digit Span subtests of the Freedom from Distractibility index were significantly higher in ASD than in ADHD, while the Picture Completion subtest was significantly lower in ASD. To our knowledge, this is the first study to evaluate the difference in the cognitive profiles of adults with ASD and those with ADHD based on the WAIS III with a large number of participants.

Linear and non-linear analyses of Conner's Continuous Performance Test-II discriminate adult patients with attention deficit hyperactivity disorder from patients with mood and anxiety disorders

BACKGROUND

Attention Deficit Hyperactivity Disorder (ADHD) is a heterogeneous disorder. Therefore it is important to look for factors that can contribute to better diagnosis and classification of these patients. The aims of the study were to characterize adult psychiatric out-patients with a mixture of mood, anxiety and attentional problems using an objective neuropsychological test of attention combined with an assessment of mood instability.

METHOD

Newly referred patients (n = 99; aged 18-65 years) requiring diagnostic evaluation of ADHD, mood or anxiety disorders were recruited, and were given a comprehensive diagnostic evaluation including the self-report form of the cyclothymic temperament scale and Conner's Continuous Performance Test II (CPT-II). In addition to the traditional measures from this test we have extracted raw data and analysed time series using linear and non-linear mathematical methods.

RESULTS

Fifty patients fulfilled criteria for ADHD, while 49 did not, and were given other psychiatric diagnoses (clinical controls). When compared to the clinical controls the ADHD patients had more omission and commission errors, and higher reaction time variability. Analyses of response times showed higher values for skewness in the ADHD patients, and lower values for sample entropy and symbolic dynamics. Among the ADHD patients 59 % fulfilled criteria for a cyclothymic temperament, and this group had higher reaction time variability and lower scores on complexity than the group without this temperament.

CONCLUSION

The CPT-II is a useful instrument in the assessment of ADHD in adult patients. Additional information from this test was obtained by analyzing response times using linear and non-linear methods, and this showed that ADHD patients with a cyclothymic temperament were different from those without this temperament.

Deficits in Verbal Working Memory among College Students with Attention-Deficit/Hyperactivity Disorder Traits: An Event-related Potential Study

Objective

This study investigated verbal working memory in college students with traits of attention-deficit/hyperactivity disorder (ADHD) using event-related potentials and the 2-back task.

Methods

Based on scores on the Adult ADHD Self-Report Scale and Conners’ Adult ADHD Rating Scale, participants were assigned to the normal control (n=28) or ADHD-trait (n=29) group. The 2-back task, which was administered to evaluate working memory, consists of a congruent condition, under which the current stimulus is the same as the one presented two trials earlier, and an incongruent condition, under which the current stimulus is not the same as the one presented two trials earlier. The numbers 1, 2, 3, and 4 were used as stimuli.

Results

On the 2-back task, the ADHD-trait group committed significantly more errors in response to congruent stimuli and showed a smaller P300 amplitude than did the control group.

Conclusion

These results indicate that college students with ADHD traits have deficits in verbal working memory, possibly due to difficulties in memory updating or attentional allocation.

Cognitive heterogeneity in adult attention deficit/hyperactivity disorder: A systematic analysis of neuropsychological measurements

Attention Deficit/Hyperactivity Disorder (ADHD) in childhood is associated with impaired functioning in multiple cognitive domains: executive functioning (EF), reward and timing. Similar impairments have been described for adults with persistent ADHD, but an extensive investigation of neuropsychological functioning in a large sample of adult patients is currently lacking. We systematically examined neuropsychological performance on tasks measuring EF, delay discounting, time estimation and response variability using univariate ANCOVA's comparing patients with persistent ADHD (N=133, 42% male, mean age 36) and healthy adults (N=132, 40% male, mean age 36). In addition, we tested which combination of variables provided the highest accuracy in predicting ADHD diagnosis. We also estimated for each individual the severity of neuropsychological dysfunctioning. Lastly, we investigated potential effects of stimulant medication and a history of comorbid major depressive disorder (MDD) on performance. Compared to healthy adults, patients with ADHD showed impaired EF, were more impulsive, and more variable in responding. However, effect sizes were small to moderate (range: 0.05-0.70) and 11% of patients did not show neuropsychological dysfunctioning. The best fitting model predicting ADHD included measures from distinct cognitive domains (82.1% specificity, 64.9% sensitivity). Furthermore, patients receiving stimulant medication or with a history of MDD were not distinctively impaired. To conclude, while adults with ADHD as a group are impaired on several cognitive domains, the results confirm that adult ADHD is neuropsychologically heterogeneous. This provides a starting point to investigate individual differences in terms of impaired cognitive pathways.

Gender differences in adults with attention-deficit/hyperactivity disorder: A narrative review

Certain characteristics of attention-deficit/hyperactivity disorder (ADHD) in children have long been known to differ by gender. What has not been as widely studied is whether gender is similarly associated with ADHD differences in adults. In this review, the relation between gender and adult ADHD prevalence, persistence, impairment, comorbidity, cognitive functioning, and treatment response was examined across 73 studies. Although gender was related to several characteristics and correlates of adult ADHD, it appeared that many of these gender differences may be at least be partially attributed to methodological artifacts or social and cultural influences, rather than fundamental differences in the expression of ADHD in men and women. We highlight how understanding the nature of the relation between gender and ADHD across the lifespan is complicated by a number of methodological difficulties, and offer recommendations for how emerging research and clinical practice can better incorporate gender into the conceptualization of ADHD in adulthood.

A meta-analysis of decision-making and attention in adults with ADHD

OBJECTIVE

Deficient reward processing has gained attention as an important aspect of ADHD, but little is known about reward-based decision-making (DM) in adults with ADHD. This article summarizes research on DM in adult ADHD and contextualizes DM deficits by comparing them to attention deficits.

METHOD

Meta-analytic methods were used to calculate average effect sizes for different DM domains and continuous performance task (CPT) measures.

RESULTS

None of the 59 included studies (DM: 12 studies; CPT: 43; both: 4) had indications of publication bias. DM and CPT measures showed robust, small to medium effects. Large effect sizes were found for a drift diffusion model analysis of the CPT.

CONCLUSION

The results support the existence of DM deficits in adults with ADHD, which are of similar magnitude as attention deficits. These findings warrant further examination of DM in adults with ADHD to improve the understanding of underlying neurocognitive mechanisms.

Working memory functioning in children with attention-deficit/hyperactivity disorder (ADHD): A comparison between subtypes and normal controls

OBJECTIVE

Children with attention-deficit/hyperactivity disorder (ADHD) often experience working memory difficulties. However, research findings are inconsistent, making it difficult to compare results across studies. There are several reasons for this inconsistency. Firstly, most studies make no distinction between ADHD subtypes, despite evidence that predominantly inattentive ADHD (ADHD/I) represents a different neurocognitive profile to the hyperactive-impulsive subtype (ADHD/HI). Secondly, documented studies use different tests of working memory which may be measuring different skills. Some assess only the verbal components of working memory and others the visuo-spatial; few of the tests assess both. Further, some tests employ a recognition methodology and others use recall, which require different brain regions and cognitive processes. To clarify these inconsistencies, the verbal and visuo-spatial working memory of children with ADHD/I, ADHD/HI and a control group with no ADHD symptoms were compared.

METHOD

The Automated Working Memory Assessment and Ravens Coloured Progressive Matrices were administered to 72 children (ADHD/I n = 27; ADHD/HI n = 25; control n = 20).

RESULTS

The ADHD groups performed similarly, but were significantly poorer than the control group in all aspects of working memory. Storage abilities were stronger than processing abilities, while verbal and visuo-spatial abilities were equally developed for all groups.

CONCLUSION

ADHD-related deficits were apparent across working memory components, even when IQ was controlled for, suggesting a generalised impairment.

Pilot randomized controlled trial of dialectical behavior therapy group skills training for ADHD among college students

OBJECTIVE

ADHD affects between 2% and 8% of college students and is associated with broad functional impairment. No prior randomized controlled trials with this population have been published. The present study is a pilot randomized controlled trial evaluating dialectical behavior therapy (DBT) group skills training adapted for college students with ADHD.

METHOD

Thirty-three undergraduates with ADHD between ages 18 and 24 were randomized to receive either DBT group skills training or skills handouts during an 8-week intervention phase. ADHD symptoms, executive functioning (EF), and related outcomes were assessed at baseline, post-treatment, and 3-month follow-up.

RESULTS

Participants receiving DBT group skills training showed greater treatment response rates (59-65% vs. 19-25%) and clinical recovery rates (53-59% vs. 6-13%) on ADHD symptoms and EF, and greater improvements in quality of life.

CONCLUSION

DBT group skills training may be efficacious, acceptable, and feasible for treating ADHD among college students. A larger randomized trial is needed for further evaluation.

Comparing the executive attention of adult females with ADHD to that of females with sensory modulation disorder (SMD) under aversive and non-aversive auditory conditions

Certain behavioral expressions of sensory modulation disorder (SMD) such as distractibility, hyperactivity, and impulsivity are often similar to those of attention deficit/hyperactivity disorder (ADHD) in pediatric and adult populations. There is also a high comorbidity rate between these two diagnoses and absence of research regarding the objective neuropsychological differentiation between them. In the present study we employed a factorial design which enabled us to: (a) systematically examine the effects of SMD and ADHD on executive attention in a sample of adult females using a Stroop-like task, and (b) measure the effect of aversive conditions (sounds) on executive attention. The experimental measures used were the Stroop-like Location-Direction Task (SLDT) to assess executive attention and the battery of aversiveness to sounds (BAS), a standardized measure of aversive sounds that was developed for this study and enabled individual customization of aversive auditory sounds. Results revealed, as expected, a specific core deficit in executive attention for the ADHD factor. In addition to that, the present study provides an important, pioneering finding of SMD impairment in a unique combination of a cognitively demanding task with aversive sounds, providing preliminary objective evidence differentiating SMD from ADHD.

ADHD predominantly inattentive subtype with high sluggish cognitive tempo: a new clinical entity?

OBJECTIVE

The authors investigate differences in the neuropsychological and behavioral profiles of two groups of children with ADHD, one with predominantly inattentive subtype of ADHD (PI) and high sluggish cognitive tempo (SCT; n = 19) and another formed by the rest of the sample (children with ADHD combined subtype and children with PI and low SCT scores; n = 68).

METHOD

Instruments included Wechsler Intelligence Scale for Children and subtests from Developmental Neuropsychological Assessment, Conners' Continuous Performance Test, Behavior Rating Inventory of Executive Function, and Achenbach's Child Behavior Checklist for ages 6 to 18.

RESULTS

PI with high SCT had fewer problems with sustained attention, and more internalizing problems, anxiety/depression, and withdrawn/depressed behavior, and more executive problems with self-monitoring than the rest of the ADHD sample.

CONCLUSION

This study supports revising subtype's criteria and further studying the hypothesis that ADHD with high SCT constitutes a separate clinical entity.

Acute neuropharmacological effects of atomoxetine on inhibitory control in ADHD children: a fNIRS study

The object of the current study is to explore the neural substrate for effects of atomoxetine (ATX) on inhibitory control in school-aged children with attention deficit hyperactivity disorder (ADHD) using functional near-infrared spectroscopy (fNIRS). We monitored the oxy-hemoglobin signal changes of sixteen ADHD children (6–14 years old) performing a go/no-go task before and 1.5 h after ATX or placebo administration, in a randomized, double-blind, placebo-controlled, crossover design. Sixteen age- and gender-matched normal controls without ATX administration were also monitored. In the control subjects, the go/no-go task recruited the right inferior and middle prefrontal gyri (IFG/MFG), and this activation was absent in pre-medicated ADHD children. The reduction of right IFG/MFG activation was acutely normalized after ATX administration but not placebo administration in ADHD children. These results are reminiscent of the neuropharmacological effects of methylphenidate to up-regulate reduced right IFG/MFG function in ADHD children during inhibitory tasks. As with methylphenidate, activation in the IFG/MFG could serve as an objective neuro-functional biomarker to indicate the effects of ATX on inhibitory control in ADHD children. This promising technique will enhance early clinical diagnosis and treatment of ADHD in children, especially in those with a hyperactivity/impulsivity phenotype.

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We assessed the effects of atomoxetine administration to ADHD children using fNIRS.

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Normal healthy control subjects recruited the right IFG/MFG during go/no-go tasks.

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Pre-medicated ADHD children exhibited reduced right IFG/MFG activation.

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The activation was acutely normalized by atomoxetine, but not by placebo.

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The right IFG/MFG activation may serve as an objective neuro-functional biomarker.

A double-edged sword: volatile anesthetic effects on the neonatal brain

The use of volatile anesthetics, a group of general anesthetics, is an exceedingly common practice. These anesthetics may have neuroprotective effects. Over the last decade, anesthetic induced neurotoxicity in pediatric populations has gained a certain notoriety based on pre-clinical cell and animal studies demonstrating that general anesthetics may induce neurotoxicity, including neuroapoptosis, neurodegeneration, and long-term neurocognitive and behavioral deficits. With hundreds of millions of people having surgery under general anesthesia worldwide, and roughly six million children annually in the U.S. alone, the importance of clearly defining toxic or protective effects of general anesthetics cannot be overstated. Yet, with our expanding body of knowledge, we have come to learn that perhaps not all volatile anesthetics have the same pharmacological profiles; certain ones may have a more favorable neurotoxic profile and may actually exhibit neuroprotection in specific populations and situations. Thus far, very few clinical studies exist, and have not yet been convincing enough to alter our practice. This review will provide an update on current data regarding volatile anesthetic induced neurotoxicity and neuroprotection in neonatal and infant populations. In addition, this paper will discuss ongoing studies and the trajectory of further research over the coming years.

Do cognitive measures of response inhibition differentiate between attention deficit/hyperactivity disorder and borderline personality disorder?

This study examined whether cognitive measures of response inhibition derived from the AX-CPT are able to differentiate between adult attention deficit/hyperactivity disorder (ADHD), borderline personality disorder (BPD), and healthy controls (HC). Current DSM-IV-TR symptoms of ADHD and BPD were assessed by structured diagnostic interviews, and parent developmental interviews were used to assess childhood ADHD symptoms. Patients (14 ADHD, 12 BPD, 7 ADHD and BPD, and 37 HC) performed the AX-CPT. Seventy percent of AX-CPT trials were target (AX) trials, creating a bias to respond with a target response to X probes in the nontarget (AY, BX, BY) trials. On BX trials, context, i.e. the non-'A' letter, must be used to inhibit this prepotent response tendency. On AY trials context actually causes individuals to false alarm. The effects of ADHD and BPD on AX-CPT outcome were tested using two-way ANOVA. BPD was associated with higher percentage of errors across the task and more errors and slower responses on BX trials, whereas ADHD was associated with slower responses on AY trials. The findings suggest response inhibition problems to be present in both ADHD and BPD, and patients with BPD to be particularly impaired due to poor context processing.

Neurocognitive disorders in sentenced male offenders: implications for rehabilitation

BACKGROUND

Neurocognitive deficits are frequent among male offenders and tend to be associated with a more serious risk of anti-social activity, but they are not systematically allowed for in rehabilitation programmes.

AIM

The aim of this study was to evaluate neurocognitive performance in a sample of sentenced Finnish male prisoners and consider the implications for prison programme entry.

METHODS

Seventy-five sentenced male prisoners were examined using a neurocognitive test battery.

RESULTS

Depending on the neurocognitive domain, from 5% to 49% of the men demonstrated marked neurocognitive deficits in tests of motor dexterity, visuospatial/construction skills, verbal comprehension, verbal and visual memory and attention shift. Verbal IQ was more impaired than performance IQ. There was no association between most serious offence type and neurocognitive performance, but correlations between attention deficit indices and number of previous convictions suggested that recidivists may have an attention disorder profile. Cluster analysis identified two subgroups of offenders, separated by very poor or merely poor cognitive performance. Motor dexterity, visuo-construction and verbal memory deficits were not wholly explained by lower IQ measures.

CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

Our sample was small, but the nature and extent of the neurocognitive deficits found suggest that wider use of neurocognitive assessments, which the men generally tolerated well, could help select those most likely to need offender programmes and that the effectiveness of these may be enhanced by some specific cognitive remediation before progressing to more complex social tasks.

Cool and hot executive function in conduct-disordered adolescents with and without co-morbid attention deficit hyperactivity disorder: relationships with externalizing behaviours

BACKGROUND

An understanding of the exact nature of executive function (EF) deficits in conduct disorder (CD) remains elusive because of issues of co-morbidity with attention deficit hyperactivity disorder (ADHD).

METHOD

Seventy-two adolescents with CD, 35 with CD + ADHD and 20 healthy controls (HCs) were assessed on a computerized battery of putative 'cool' and 'hot' EFs. Participants also completed the Child Behaviour Checklist (CBCL).

RESULTS

In the cool EF tasks such as planning, the CD + ADHD group in particular showed most notable impairments compared to HCs. This pattern was less evident for set shifting and behavioural inhibition but there were significant correlations between errors scores on these tasks and indices of externalizing behaviours on the CBCL across the sample. For hot EF tasks, all clinical groups performed worse than HCs on delay of gratification and poor performance was correlated with externalizing scores. Although there were no notable group differences on the punishment-based card-playing task, there were significant correlations between ultimate payout and externalizing behaviour across groups.

CONCLUSIONS

Overall, our findings highlight the fact that there may be more common than distinguishing neuropsychological underpinnings to these co-morbid disorders and that a dimensional symptom-based approach may be the way forward.

Cognitive deficits in adults with ADHD go beyond comorbidity effects

OBJECTIVE

This study addresses if deficits in cognitive, attention, and inhibitory control performance in adults with ADHD are better explained by the disorder itself or by comorbid conditions.

METHOD

Adult patients with ADHD (n = 352) and controls (n = 94) were evaluated in the ADHD program of a tertiary hospital. The diagnostic process for ADHD and comorbidities was based on Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) criteria. Stepwise regression analyses evaluated the effect of ADHD, demographics, and comorbidities on the scores from Wechsler Adult Intelligence Scale-Revised, Continuous Performance Test, and Stroop Color and Word Test.

RESULTS

Patients with ADHD of both genders had worse performance on neuropsychological domains, even after adjustment for comorbidities. The presence of comorbid bipolar disorder and specific phobia are associated with more Stroop errors, whereas patients with generalized anxiety disorder present a longer execution time in Stroop.

CONCLUSION

Neuropsychological deficits in adults with ADHD go beyond comorbidity. Specific comorbid disorders may influence the neuropsychological functioning in adults with ADHD.

Constraints on information processing capacity in adults with ADHD

OBJECTIVE

Researchers in the cognitive sciences have demonstrated the existence of processing capacity bottlenecks in the human brain. These capacity bottlenecks restrict our ability to process and act on environmental information. The purpose of the current study was to examine whether adults with attention-deficit hyperactivity disorder (ADHD) show reduced capacity of working memory and response selection mechanisms.

METHOD

Thirty-eight young adults with ADHD and 33 comparison adults were assessed using two measures of processing capacity. A dual choice-response task (psychological refractory period [PRP] task) measured response selection capacity, and an n-back task measured working memory capacity. These tasks measured capacity by assessing the degree to which increasing processing load disrupted performance.

RESULTS

Results confirmed that performance declined as cognitive load was increased, and this was true for both groups on each task. On the PRP task, the performance decline resulting from increased cognitive load was more pronounced in the ADHD group than in the control group, indicative of reduced response selection capacity in the ADHD group. On the n-back task, however, there was no group difference in the degree to which increasing processing load disrupted performance.

CONCLUSIONS

Results indicate that adults with ADHD show a specific capacity reduction of response selection. This evidence suggests a dissociation between working memory and response selection capacities, and it may have implications for understanding cognitive dysfunction in adults with ADHD.

Complex prospective memory in adults with attention deficit hyperactivity disorder

Objectives

Attention deficit hyperactivity disorder (ADHD) in adults has been associated with disturbances of attention and executive functions. Furthermore, impairments of verbal and figural retrospective memory were reported. However, little is known about the effects of ADHD on prospective memory, the execution of delayed intentions in the future.

Methods

The present study compared the performance of 45 adult patients with ADHD not treated with stimulant medication with the performance of 45 matched healthy individuals on a paradigm of complex prospective memory which measured task planning, plan recall, self-initiation and execution. Furthermore, the contribution of other cognitive functions to prospective memory functioning was assessed, including measures of attention, executive functions and memory.

Results

A large-scale impairment could be observed in task planning abilities in patients with ADHD. Only negligible to small effects were found for plan recall, self-initiation and execution. Inhibition was identified to contribute significantly to performance on task planning.

Conclusions

The present findings suggest that four cognitive components contribute to the performance of prospective memory. Impairments of prospective memory mainly emerged from deficient planning abilities in adults with ADHD. Implications on behavioral based intervention strategies are discussed.

Are language production problems apparent in adults who no longer meet diagnostic criteria for attention-deficit/hyperactivity disorder?

In this study, we examined sentence production in a sample of adults (N = 21) who had had attention-deficit/hyperactivity disorder (ADHD) as children, but as adults no longer met DSM-IV diagnostic criteria (APA, 2000). This "remitted" group was assessed on a sentence production task. On each trial, participants saw two objects and a verb. Their task was to construct a sentence using the objects as arguments of the verb. Results showed more ungrammatical and disfluent utterances with one particular type of verb (i.e., participle). In a second set of analyses, we compared the remitted group to both control participants and a "persistent" group, who had ADHD as children and as adults. Results showed that remitters were more likely to produce ungrammatical utterances and to make repair disfluencies compared to controls, and they patterned more similarly to ADHD participants. Conclusions focus on language output in remitted ADHD, and the role of executive functions in language production.

Biomarkers for attention-deficit/hyperactivity disorder (ADHD). A consensus report of the WFSBP task force on biological markers and the World Federation of ADHD

OBJECTIVE

Psychiatric "nosology" is largely based on clinical phenomenology using convention-based diagnostic systems not necessarily reflecting neurobiological pathomechanisms. While progress has been made regarding its molecular biology and neuropathology, the phenotypic characterization of ADHD has not improved. Thus, validated biomarkers, more directly linked to the underlying pathology, could constitute an objective measure for the condition.

METHOD

The task force on biological markers of the World Federation of Societies of Biological Psychiatry (WFSBP) and the World Federation of ADHD commissioned this paper to develop a consensus report on potential biomarkers of ADHD. The criteria for biomarker-candidate evaluation were: (1) sensitivity >80%, (2) specificity >80%, (3) the candidate is reliable, reproducible, inexpensive, non-invasive, easy to use, and (4) confirmed by at least two independent studies in peer-reviewed journals conducted by qualified investigators.

RESULTS

No reliable ADHD biomarker has been described to date, but some promising candidates (e.g., olfactory sensitivity, substantial echogenicity) exist. A problem in the development of ADHD markers is sample heterogeneity due to aetiological and phenotypic complexity and age-dependent co-morbidities.

CONCLUSIONS

Most likely, no single ADHD biomarker can be identified. However, the use of a combination of markers may help to reduce heterogeneity and to identify homogeneous subtypes of ADHD.

Smell identification function in children with attention deficit hyperactivity disorder

OBJECTIVE

Deficits in olfactory function are common features in neurodegenerative and neuropsychiatric disorders. Olfactory processing is related to dopamine metabolism and orbitofrontal cortex functioning, both known to be involved in the neurobiology of ADHD. Some investigations suggested alterations in olfactory processing (identification and detection threshold) in patients with ADHD. Despite increasing knowledge, controversy about this topic still exists regarding children with ADHD. This study was conducted to help elucidate some of this controversy.

METHODS

50 participants (8-15 years, mean=10.70±1.77) with ADHD were compared to 50 controls. The two groups were well matched for age, gender and Mean School Scores (MSS). We assessed odor identification and threshold through a smell test composed of two tests of identification and detection threshold. Odor detection threshold was assessed with the odorant phenyl ethyl alcohol solved in propylene glycol using a single staircase method. Odor identification was assessed with chemical essences of five common odorants.

RESULTS

The mean Sensory Identification Score for children with ADHD and the control groups were 3.76 (1.06) and 4.46 (0.76), respectively (p<0.001). The mean for Sensory Threshold Score for ADHD and control group was 6.4 (3.35) and 9.75 (2.16), respectively (p<0.001).

CONCLUSION

This study replicated altered olfactory performance in ADHD. Substantial olfactory deficits across the two domains of identification and detection threshold are observed in children with ADHD. These deficits do not seem to be a result of olfactory task difficulty and are not influenced by age, gender and MSS. Further studies are required to investigate whether olfactory function can be used as a biological marker for early diagnosis, treatment and prognosis of ADHD.

Sex differences in the manifestation of ADHD in emerging adults

OBJECTIVE

Given the mixed literature in the area, the aim of the current study was to determine whether sex differences exist in inattention, hyperactivity, and impairment in college adults with ADHD.

METHOD

Individuals from three universities were recruited for the study. Participants with (n = 164) and without ADHD (n = 710) completed on-line measures of symptoms and impairment.

RESULTS

College women with ADHD were shown to have higher rates of inattention, hyperactivity, and impairment than college women without ADHD and college men with ADHD. Analyses revealed that women in college who have ADHD experience higher levels of impairment in the following domains: home life, social life, education, money management, and daily life activities.

CONCLUSION

Overall, clear differences emerged between men and women with ADHD. Implications and future directions are discussed.