The diagnosis and neuropsychological assessment of adult attention deficit/hyperactivity disorder. Scientific study and practical guidelines

Empirically derived symptom profiles in adults with attention-Deficit/hyperactivity disorder: An unsupervised machine learning approach

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is associated with various cognitive, behavioral, and mood symptoms that complicate diagnosis and treatment. The heterogeneity of these symptoms may also vary depending on certain sociodemographic factors. It is therefore important to establish more homogenous symptom profiles in patients with ADHD and determine their association with the patient's sociodemographic makeup. The current study used unsupervised machine learning to identify symptom profiles across various cognitive, behavioral, and mood symptoms in adults with ADHD. It was then examined whether symptom profiles differed based on relevant sociodemographic factors.

METHODS

Participants were 382 adult outpatients (62% female; 51% non-Hispanic White) referred for neuropsychological evaluation for ADHD.

RESULTS

Employing Gaussian Mixture Modeling, we identified two distinct symptom profiles in adults with ADHD: "ADHD-Plus Symptom Profile" and "ADHD-Predominate Symptom Profile." These profiles were primarily differentiated by internalizing psychopathology (Cohen's d = 1.94-2.05), rather than by subjective behavioral and cognitive symptoms of ADHD or neurocognitive test performance. In a subset of 126 adults without ADHD who were referred for the same evaluation, the unsupervised machine learning algorithm only identified one symptom profile. Group comparison analyses indicated that female patients were most likely to present with an ADHD-Plus Symptom Profile (χ2 = 5.43, p < .001).

CONCLUSION

The machine learning technique used in this study appears to be an effective way to elucidate symptom profiles emerging from comprehensive ADHD evaluations. These findings further underscore the importance of considering internalizing symptoms and patients' sex when contextualizing adult ADHD diagnosis and treatment.

Determining cutoff scores on the Conners' adult ADHD rating scales that can definitively rule out the presence of ADHD in a clinical sample

In recent years, the prevalence of Attention Deficit/Hyperactivity Disorder (ADHD) and the number of individuals seeking ADHD assessments has risen significantly, leading to an increased demand for accurate diagnostic tools. This study aimed to identify cutoff scores on the Conners' Adult ADHD Rating Scales (CAARS-S:L) that can definitively rule out the presence of ADHD. Among 102 clinically diagnosed adult ADHD participants and 448 non-ADHD participants who completed the CAARS-S:L, a receiver operating characteristic curve analysis established a perfectly discriminant cutoff T-score of <44 on the ADHD Symptoms Total subscale when looking at any ADHD diagnosis and <54 on the Inattentive Symptoms subscale when looking at individuals diagnosed with the inattentive subtype of ADHD. Alternative cutoffs of <54 (ADHD Symptoms Total subscale) and <63 (Inattentive Symptoms subscale) were also identified, both with a sensitivity of 0.95 or higher. Furthermore, the analysis found the ADHD Index to be a poor predictor of a negative ADHD diagnosis, suggesting against the use of this scale for cutoff determination. Despite this limitation, these findings indicate that with specific cutoffs, the CAARS-S:L may have the potential to conclusively rule out ADHD, effectively streamlining the diagnostic process and reducing unnecessary comprehensive assessments in clear negative cases.

Do we over-diagnose ADHD in North America? A critical review and clinical recommendations

There has been a marked increase in the prevalence of attention-deficit/hyperactivity disorder (ADHD) in the last 25 years in North America. Some see this trend as positive and believe that it reflects a better identification of ADHD and even think that the disorder is still under-diagnosed. Others, however, contend that ADHD is over-diagnosed. To help mental health clinicians to maintain an informed and nuanced perspective on this debate, this critical review aims to (1) summarize empirical results on factors that might contribute to increase the number of ADHD diagnoses and (2) propose clinical recommendations coherent with these findings to improve clinical practices for ADHD assessment and treatment. We conclude that artifactual factors such as current formulation of diagnostic criteria, clinical practices, and inordinate focus on performance, which is rampant in North America, likely contribute to inflated prevalence rates.

Non-credible symptom report in the clinical evaluation of adult ADHD: development and initial validation of a new validity index embedded in the Conners' adult ADHD rating scales

As attention-deficit/hyperactivity disorder (ADHD) is a feasible target for individuals aiming to procure stimulant medication or accommodations, there is a high clinical need for accurate assessment of adult ADHD. Proven falsifiability of commonly used diagnostic instruments is therefore of concern. The present study aimed to develop a new, ADHD-specific infrequency index to aid the detection of non-credible self-report. Disorder-specific adaptations of four detection strategies were embedded into the Conners’ Adult ADHD Rating Scales (CAARS) and tested for infrequency among credible neurotypical controls (n = 1001) and credible adults with ADHD (n = 100). The new index’ ability to detect instructed simulators (n = 242) and non-credible adults with ADHD (n = 22) was subsequently examined using ROC analyses. Applying a conservative cut-off score, the new index identified 30% of participants instructed to simulate ADHD while retaining a specificity of 98%. Items assessing supposed symptoms of ADHD proved most useful in distinguishing genuine patients with ADHD from simulators, whereas inquiries into unusual symptom combinations produced a small effect. The CAARS Infrequency Index (CII) outperformed the new infrequency index in terms of sensitivity (46%), but not overall classification accuracy as determined in ROC analyses. Neither the new infrequency index nor the CII detected non-credible adults diagnosed with ADHD with adequate accuracy. In contrast, both infrequency indices showed high classification accuracy when used to detect symptom over-report. Findings support the new indices’ utility as an adjunct measure in uncovering feigned ADHD, while underscoring the need to differentiate general over-reporting from specific forms of feigning.

Neurocognitive Functions in Bipolar Disorder in Relation to Comorbid ADHD

Introduction

Bipolar disorder (BD) and attention deficit hyperactivity disorder (ADHD) often co-occur in adult population. Both conditions present various neurocognitive and behavioral problems. We aimed to examine neurocognitive functions in adult patients with comorbid BD and ADHD (BD+ADHD) in comparison to patients with only BD, only ADHD and healthy controls (HCs).

Method

An extensive cognitive battery which evaluates verbal learning and memory, visual memory, processing speed, attention, executive functions, working memory and verbal fluency, was used to assess neurocognitive functions respectively in adult (age 18-65 years) patients with BD (n=37), ADHD (n=43), BD+ADHD (n=20) in comparison to HCs (n=51). The Multivariate Analysis of Covariance models, where age, level of education and total BIS-11 scores were included as covariates, were used for comparing neurocognitive scores among groups.

Results

Both BD and BD+ADHD groups showed significantly poorer performance than HCs in processing speed, attention, executive functions, and verbal fluency domains. The BD group had additional significant deficits in executive functions, verbal learning and memory domains. There were no significant differences between BD and BD+ADHD groups with regards to verbal learning and memory, visual memory, processing speed, attention, executive functions, working memory and verbal fluency domains. Patients with only ADHD showed significantly poorer performance than HCs in verbal fluency domain.

Conclusions

Our results show similarities in the neurocognitive functions of adults with BD and BD+ADHD across a wide range of cognitive domains. The findings point to the need for further exploration of diverging and converging neurodevelopmental trajectories of BD and ADHD.

Diagnostic Accuracy of the Conners' Adult ADHD Rating Scale in a Postsecondary Population

Objective: Clinicians frequently rely upon the results of self-report rating scales when making the diagnosis of ADHD; however, little research exists regarding the ability of self-report measures to accurately differentiate ADHD from other disorders. Method: This present study investigated the ability of the Conners' Adult ADHD Rating Scale (CAARS) to discriminate between 249 postsecondary students with carefully diagnosed ADHD and 507 clinical controls. Results: The overall discriminant validity of the CAARS was 69%, and it had an unacceptably high false positive and false negative rate. At lower prevalence rates, a high score on the CAARS has only a 22% chance of accurately identifying individuals with ADHD. Conclusion: Although the CAARS is an adequate screening measure, it should not be the main method by which a diagnosis is made, as it frequently misidentifies individuals with other psychological complaints as having ADHD. Implications for clinical practice are discussed.

Verbal Memory Function in Intellectually Well-Functioning Adults With ADHD: Relations to Working Memory and Response Inhibition

Objective: To investigate verbal memory function with relation to working memory (WM) and response inhibition (RI) in adults with ADHD. Method: Verbal memory function was assessed by the California Verbal Learning Test-Second Edition (CVLT-II), WM by the Paced Serial Addition Test, and RI by the Color-Word Interference Test from Delis-Kaplan Executive Function System in a sample of adults with normal to high intellectual function (IQ). Results: The ADHD group (n = 74) obtained lower scores than controls on measures of learning, recall, and immediate memory (CVLT-II). WM and RI explained a substantial part of verbal memory performance in both groups. A group to executive function (EF) interaction effect was identified for the total number of intrusions and false positive responses on the CVLT-II recognition trial. Conclusion: Verbal memory performance only partially overlaps with EF in intellectually well-functioning adults with ADHD. Both EF and verbal memory function should be assessed as part of a neuropsychological evaluation of adults with ADHD. (J. of Att. Dis. XXXX; XX(X) XX-XX).

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.

Rapid screening for cognitive deficits in attention deficit and hyperactivity disorders with the screen for cognitive impairment in psychiatry

Cognitive impairments constitute a core feature of attention deficit and hyperactivity disorders (ADHD), but are infrequently assessed in the clinical setting. We have previously demonstrated the ability of an objective cognitive battery, the Screen for Cognitive Impairment in Psychiatry (SCIP), to differentiate adult ADHD patients from healthy controls in five cognitive domains. Here, we further characterize these subtle cognitive deficits by conducting additional univariate analyses on our ADHD dataset to assess the contributions of various demographic characteristics on SCIP performance and to determine correlations between SCIP scores and scores on other measures evaluating illness severity, perceived cognitive deficits, and overall functioning. Age and years of education were moderately associated with performance on the SCIP and/or its subscales in our ADHD cohort. The SCIP global index score was moderately correlated with clinician-rated measures of illness severity and weakly associated with clinician-rated overall functional status. Intriguingly, overall SCIP performance was only weakly associated with patient self-reported measures of cognitive functioning. Of practical importance, small-to-moderate associations were consistently observed between performances on two subscales of the SCIP and the other measures evaluating illness severity, overall functioning, and patient self-reported cognitive functioning (the working memory and visuomotor tracking subscales). Thus, these data demonstrate that the SCIP, particularly the working memory and visuomotor tracking subscales, is sensitive enough to detect cognitive deficits in adult patients with ADHD, and that these deficits are correlated with functional impairments. Furthermore, these data highlight the importance of integrating both objective and subjective evaluations of cognition in adult ADHD.

Analysis of cognitive and attentional profiles in children with and without ADHD using an innovative virtual reality tool

In previous studies, children with Attention-Deficit Hyperactivity Disorder (ADHD) have been found to have more difficulties with processing speed, working memory, and attentional tasks. The present study aimed to compare the cognitive variables (working memory and processing speed) and the attentional profiles of a sample of students with and without ADHD, using scales from the WISC-IV, and the virtual reality-based attentional test known as 'Aula Nesplora'; and determine the extent to which the aforementioned variables may predict student group membership. A total of 88 students took part in this study (66 males and 22 females), aged from 6 to 16 years (M = 10.20; SD = 2.79). The sample was divided into two groups: an ADHD group (n = 50) and a Control group (n = 38). Students in the ADHD group obtained lower scores in working memory and in processing speed, as well as demonstrating poorer performance in Aula Nesplora than did their peers. Working memory, and the number of omissions, were both shown to be reliable predictors of group membership. This study revealed the importance of obtaining data from attentional variables differentiated by modality when considering cognitive variables, in order to better characterize the difficulties experienced by individuals diagnosed with ADHD.

Association Between Continuous Performance and Response Inhibition Tests in Adults With ADHD

OBJECTIVE

The study of ADHD uses various computerized tests to assess cognitive functions. Uncertainty exists regarding the association between deficits found by different tools testing similar or different cognitive functions (e.g., continuous performance tests [CPT] and response inhibition [RI] tests).We hypothesized that different tools that measure continuous performance will be better correlated between themselves than with a tool that examines RI.

METHOD

Thirty-six adults with ADHD performed two different CPTs and a RI task. We analyzed correlations between different measures examined by the tasks.

RESULTS

There were strong correlations between corresponding measures in the CPTs. Correlations between the results in CPT and the RI task were only minimal.

CONCLUSION

These findings support the specificity of impairments in different cognitive domains (continuous attention vs. RI) beyond the specific test used in the study of ADHD. Also, these findings strengthen the importance of specific discriminative cognitive domains in ADHD.

The Altered Brain Activation of Phonological Working Memory, Dual Tasking, and Distraction Among Participants With Adult ADHD and the Effect of the MAOA Polymorphism

OBJECTIVE

The present study aimed to reveal the brain correlates of phonological working memory (WM), dual tasking, and distraction in adult ADHD combined with the effect of polymorphisms of monoamine oxidase A ( MAOA rs1137070 Asp470Asp).

METHOD

A total of 29 participants with adult ADHD and 21 controls were recruited. They completed 0-back and 2-back tasks, as wells as 2-back tasks with a dual-task effect or a distracting effect, during functional magnetic resonance imaging scanning.

RESULTS

The brain activation of WM in the bilateral inferior frontal lobe, pars opercularis, was higher among the adult ADHD group. The genotype of MAOA significantly interacted with the ADHD effect in the left inferior frontal lobe, pars opercularis. Adults with ADHD had higher activation in the left lingual area in response to the dual-tasking effect.

CONCLUSION

The MAOA polymorphism moderated the altered activation in pars opercularis for WM among adults with ADHD. The higher lingual gyrus activation might indicate that higher attention resources are demanded to sustain the dual-task function of adults with ADHD.

A Genome-Wide Association Study of Attention Function in a Population-Based Sample of Children

Background

Attention function filters and selects behaviorally relevant information. This capacity is impaired in some psychiatric disorders and has been proposed as an endophenotype for Attention-Deficit/Hyperactivity Disorder; however, its genetic basis remains largely unknown. This study aimed to identify single nucleotide polymorphism (SNPs) associated with attention function.

Materials and Methods

The discovery sample included 1655 children (7–12 years) and the replication sample included 546 children (5–8 years). Five attention outcomes were assessed using the computerized Attentional Network Test (ANT): alerting, orienting, executive attention, Hit Reaction time (HRT) and the standard error of HRT (HRTSE). A Genome-wide Association Study was conducted for each outcome. Gene set enrichment analyses were performed to detect biological pathways associated with attention outcomes. Additional neuroimaging analyses were conducted to test neural effects of detected SNPs of interest.

Results

Thirteen loci showed suggestive evidence of association with attention function (P<10⁻⁵) in the discovery sample. One of them, the rs4321351 located in the PID1 gene, was nominally significant in the replication sample although it did not survive multiple testing correction. Neuroimaging analysis revealed a significant association between this SNP and brain structure and function involving the frontal-basal ganglia circuits. The mTOR signaling and Alzheimer disease-amyloid secretase pathways were significantly enriched for alerting, orienting and HRT respectively (FDR<5%).

Conclusion

These results suggest for the first time the involvement of the PID1 gene, mTOR signaling and Alzheimer disease-amyloid secretase pathways, in attention function during childhood. These genes and pathways have been proposed to play a role in neuronal plasticity, memory and neurodegenerative disease.

Is excessive electroencephalography beta activity associated with delinquent behavior in men with attention-deficit hyperactivity disorder symptomatology?

BACKGROUND/AIMS

The attention-deficit/hyperactivity disorder (ADHD) shows an increased prevalence in delinquents compared to the normal population. In recent studies, a subgroup of subjects with ADHD as well as a subgroup of delinquents displayed excessive electroencephalography (EEG) beta activity, which has been associated with antisocial behavior in ADHD children. We investigated whether delinquent behavior in adults with ADHD symptomatology is related to excessive beta activity.

METHODS

We compared the resting state EEGs (eyes open/closed) of delinquent and nondelinquent subjects with ADHD symptoms and those of a control group regarding EEG power spectra and topography.

RESULTS

Delinquents with ADHD symptomatology showed more beta power at frontal, central and parietal brain regions than nondelinquents with ADHD symptoms.

CONCLUSION

Excessive beta power may thus represent a risk factor for delinquent behavior in adults with ADHD symptomatology. The awareness of such a risk factor may be helpful in the assessment of the risk for delinquent behavior in a psychiatric context and may provide a neurobiological background for therapeutic interventions.

The Speed of Visual Attention and Motor-Response Decisions in Adult Attention-Deficit/Hyperactivity Disorder

BACKGROUND

Adults with attention-deficit/hyperactivity disorder (ADHD) exhibit slowed reaction times (RTs) in various attention tasks. The exact origins of this slowing, however, have not been established. Potential candidates are early sensory processes mediating the deployment of focal attention, stimulus response translation processes deciding upon the appropriate motor response, and motor processes generating the response.

METHODS

We combined mental chronometry (RT) measures of adult ADHD (n = 15) and healthy control (n = 15) participants with their lateralized event-related potentials during the performance of a visual search task to differentiate potential sources of slowing at separable levels of processing: the posterior contralateral negativity (PCN) was used to index focal-attentional selection times, while the lateralized readiness potentials synchronized to stimulus and response events were used to index the times taken for response selection and production, respectively. To assess the clinical relevance of event-related potentials, a correlation analysis between neural measures and subjective current and retrospective ADHD symptom ratings was performed.

RESULTS

ADHD patients exhibited slower RTs than control participants, which were accompanied by prolonged PCN and lateralized readiness potentials synchronized to stimulus, but not lateralized readiness potentials synchronized to response events, latencies. Moreover, the PCN timing was positively correlated with ADHD symptom ratings.

CONCLUSIONS

The behavioral RT slowing of adult ADHD patients was based on a summation of internal processing delays arising at perceptual and response selection stages; motor response production, by contrast, was not impaired. The correlation between PCN times and ADHD symptom ratings suggests that this brain signal may serve as a potential candidate for a neurocognitive endophenotype of ADHD.

How Informative Is the CANTAB to Assess Executive Functioning in Children With ADHD? A Controlled Study

OBJECTIVE

The authors examined the utility of the computerized Cambridge Neuropsychological Test Automated Battery (CANTAB) to evaluate executive functioning deficits in children with ADHD.

METHOD

Participants were unmedicated children and adolescents with (n = 107) and without (n = 45) Diagnostic and Statistical Manual of Mental Disorders (4th ed.) ADHD. The authors administered the CANTAB Eclipse battery, which comprises specific tasks shown to be deficient in individuals with ADHD.

RESULTS

With the exception of the affective go/no-go total omissions, ADHD participants were significantly more impaired on all other subtests of the CANTAB in comparison with controls. Effect sizes for individual CANTAB tests were largely in the medium range with the largest effect sizes seen in spatial working memory total and between errors.

CONCLUSION

These CANTAB results are highly congruent with those reported in studies using traditional neuropsychological testing batteries, supporting the utility of the CANTAB to assess neuropsychological deficits in children with ADHD in clinical and research settings.

Attention deficit hyperactivity disorder symptoms in adults with autism spectrum disorders

Features of attention deficit hyperactivity disorder (ADHD) and impairments on neuropsychological, tests of attention have been documented in children with autism spectrum disorders (ASDs). To date, there has been a lack of research comparing attention in adults with ASD and adults with ADHD. In study 1, 31 adults with ASD and average intellectual function completed self-report measures of ADHD symptoms. These were compared with self-report measures of ADHD symptoms in 38 adults with ADHD and 29 general population controls. In study 2, 28 adults with a diagnosis of ASD were compared with an age- and intelligence quotient-matched sample of 28 adults with ADHD across a range of measures of attention. Study 1 showed that 36.7% of adults with ASD met Diagnostic and Statistical Manual-IV criteria for current ADHD "caseness" (Barkley Current self-report scores questionnaire). Those with a diagnosis of pervasive developmental disorder-not otherwise specified were most likely to describe ADHD symptoms. The ASD group differed significantly from both the ADHD and control groups on total and individual symptom self-report scores. On neuropsychological testing, adults with ASD and ADHD showed comparable performance on tests of selective attention. Significant group differences were seen on measures of attentional switching; adults with ADHD were significantly faster and more inaccurate, and individuals with Asperger's syndrome showed a significantly slower and more accurate response style. Self-reported rates of ADHD among adults with ASD are significantly higher than in the general adult population and may be underdiagnosed. Adults with ASD have attentional difficulties on some neuropsychological measures.

Higher Reported Levels of Depression, Stress, and Anxiety Are Associated With Increased Endorsement of ADHD Symptoms by Postsecondary Students

This study examined the extent to which postsecondary students endorse symptoms of Attention Deficit/Hyperactivity Disorder (ADHD) and whether experienced level of stress, depression, or anxiety are associated with higher reporting of ADHD symptoms. Students attending a combined health and counseling service completed the Conners Adult ADHD Rating Scale (CAARS), the Depression Anxiety and Stress Scale (DASS), and the Life Experiences Survey (LES). A subset also completed the Brown Attention Deficit Disorder Scale (BADDS). Findings demonstrate that the BADDS had weak specificity; 35% of never-diagnosed postsecondary students were classified as probably or very probably having ADHD based on their BAADS score. Lower false positive rates were found on the CAARS. Misdiagnosis of ADHD seems especially likely in students experiencing high levels of stress, depression, or anxiety, as these psychological conditions were associated with elevated reporting of ADHD symptoms; such conditions must therefore be considered when assessing for possible ADHD in young adults.

Sensory and sensorimotor gating in adult attention-deficit/hyperactivity disorder (ADHD)

Even though there is an impaired perceptual capacity in attention-deficit/hyperactivity disorder (ADHD) patients, psychophysiological alterations, such as impaired gating as indexed by prepulse inhibition (PPI) or suppression of P50 auditory event-related potentials, have not been found in patients with ADHD. Hence, potential relationships of psychophysiological measures of gating to psychopathology and cognitive performance remain unclear. The present study investigates two distinct operational measures of gating as well as cognitive performance within adult ADHD patients in order to assess the relationship of these measures to psychopathology. PPI, P50 suppression, cognitive performance, and psychopathologic symptoms were assessed in 26 ADHD patients and 26 healthy control subjects. ADHD patients compared to healthy control subjects exhibited impaired P50 suppression, performed worse in cognitive tasks, and reported more psychopathological symptoms, but were normal in the test of PPI. Thus, P50 gating deficits are not specific to schizophrenia-spectrum disorders. These findings highlight the differences between P50 gating and PPI as measures of the gating construct. In keeping with the lack of correlations between these two putative operational measures of gating seen in both humans and animals, adult ADHD patients exhibit deficient P50 suppression and poor cognitive performance, despite exhibiting normal levels of PPI.

Cognitive responses to stress, depression, and anxiety and their relationship to ADHD symptoms in first year psychology students

OBJECTIVE

To explore the relationship between levels of reported depression, anxiety, and stress with scores on the Conners's Adult ADHD Rating Scale (CAARS).

METHOD

Information was obtained from 84 1st-year psychology students using the CAARS, the Depression Anxiety and Stress Scale (DASS), and the Life Experiences Survey (LES).

RESULTS

Approximately 23%, 18%, and 12% of students scored above critical values on the Diagnostic and Statistical Manual of Mental Disorders (4th ed., DSM-IV) Inattention Symptoms, the DSM-IV ADHD Symptoms Total, and the Inattention/Restlessness subscales, respectively. CAARS scores were positively related to reported levels of depression, anxiety, and stress, which accounted for significant variance among the three subscales. Only 5% of participants scored above recommended critical values on the ADHD index; however, a significant amount of the variance on this measure was also attributable to the DASS.

CONCLUSION

Mood symptoms such as depression, anxiety, and stress may obscure correct attribution of cause in those being evaluated for ADHD.

Attention-deficit/hyperactivity disorder and adverse health outcomes

Attention-deficit/hyperactivity disorder (ADHD) is defined by extreme levels of inattention-disorganization and/or hyperactivity-impulsivity. In DSM-IV, the diagnostic criteria required impairment in social, academic, or occupational functioning. With DSM-5 publication imminent in 2013, further evaluation of impairment in ADHD is timely. This article reviews the current state of knowledge on health-related impairments of ADHD, including smoking, drug abuse, accidental injury, sleep, obesity, hypertension, diabetes, and suicidal behavior. It concludes by suggesting the need for new avenues of research on mechanisms of association and the potential for ADHD to be an early warning sign for secondary prevention of some poor health outcomes.

Preparatory neural networks are impaired in adults with attention-deficit/hyperactivity disorder during the antisaccade task

Adults with attention-deficit/hyperactivity disorder (ADHD) often display executive function impairments, particularly in inhibitory control. The antisaccade task, which measures inhibitory control, requires one to suppress an automatic prosaccade toward a salient visual stimulus and voluntarily make an antisaccade in the opposite direction. ADHD patients not only have longer saccadic reaction times, but also make more direction errors (i.e., a prosaccade was executed toward the stimulus) during antisaccade trials. These deficits may stem from pathology in several brain areas that are important for executive control. Using functional MRI with a rapid event-related design, adults with combined subtype of ADHD (coexistence of attention and hyperactivity problems), who abstained from taking stimulant medication 20 h prior to experiment onset, and age-match controls performed pro- and antisaccade trials that were interleaved with pro- and anti-catch trials (i.e., instruction was presented but no target appeared, requiring no response). This method allowed us to examine brain activation patterns when participants either prepared (during instruction) or executed (after target appearance) correct pro or antisaccades. Behaviorally, ADHD adults displayed several antisaccade deficits, including longer and more variable reaction times and more direction errors, but saccade metrics (i.e., duration, velocity, and amplitude) were normal. When preparing to execute an antisaccade, ADHD adults showed less activation in frontal, supplementary, and parietal eye fields, compared to controls. However, activation in these areas was normal in the ADHD group during the execution of a correct antisaccade. Interestingly, unlike controls, adults with ADHD produced greater activation than controls in dorsolateral prefrontal cortex during antisaccade execution, perhaps as part of compensatory mechanisms to optimize antisaccade production. Overall, these data suggest that the saccade deficits observed in adults with ADHD do not result from an inability to execute a correct antisaccade but rather the failure to properly prepare (i.e., form the appropriate task set) for the antisaccade trial. The data support the view that the executive impairments, including inhibitory control, in ADHD adults are related to poor response preparation.

Does age of onset of impairment impact on neuropsychological and personality features of adult ADHD?

The consideration of age of onset of impairment as part of the ADHD diagnosis is controversial and has been a revisited issue with the emergence of the new classifications in Psychiatry. The aim of this study is to compare patients with early and late onset of ADHD impairment in terms of neuropsychological and personality characteristics. Adult patients with ADHD (n = 415) were evaluated in the ADHD outpatient program at Hospital de Clínicas de Porto Alegre, Brazil. The diagnostic process for ADHD and comorbidities was based on DSM-IV criteria. The comparison between the two ages of onset groups (before 7; n = 209 or from 7 to 12 years; n = 206) was performed with ANOVA, followed by Stepwise forward regression analyses to restrict the number of comparisons and access the possible effect of multiple confounders. Patients with early onset ADHD present higher scores in novelty seeking in both analyses (respectively P = 0.016 and P = 0.002), but similar cognitive and attention features as compared with the late onset group. These data add to previous evidence that despite a more externalizing profile of early onset ADHD, the overall performance is similar reinforcing the need for awareness and inclusion of the late onset group in DSM-V diagnostic criteria.

The genetics of attention deficit/hyperactivity disorder in adults, a review

The adult form of attention deficit/hyperactivity disorder (aADHD) has a prevalence of up to 5% and is the most severe long-term outcome of this common neurodevelopmental disorder. Family studies in clinical samples suggest an increased familial liability for aADHD compared with childhood ADHD (cADHD), whereas twin studies based on self-rated symptoms in adult population samples show moderate heritability estimates of 30-40%. However, using multiple sources of information, the heritability of clinically diagnosed aADHD and cADHD is very similar. Results of candidate gene as well as genome-wide molecular genetic studies in aADHD samples implicate some of the same genes involved in ADHD in children, although in some cases different alleles and different genes may be responsible for adult versus childhood ADHD. Linkage studies have been successful in identifying loci for aADHD and led to the identification of LPHN3 and CDH13 as novel genes associated with ADHD across the lifespan. In addition, studies of rare genetic variants have identified probable causative mutations for aADHD. Use of endophenotypes based on neuropsychology and neuroimaging, as well as next-generation genome analysis and improved statistical and bioinformatic analysis methods hold the promise of identifying additional genetic variants involved in disease etiology. Large, international collaborations have paved the way for well-powered studies. Progress in identifying aADHD risk genes may provide us with tools for the prediction of disease progression in the clinic and better treatment, and ultimately may help to prevent persistence of ADHD into adulthood.

Set-shifting in adults with ADHD

Difficulties related to inhibition and set-shifting have been suggested as possible endophenotypes of Attention Deficit Hyperactivity Disorder (ADHD). However, such difficulties have not been consistently found in studies using standard neuropsychological tests. This has been partly explained by the complexity of these tests and the need to include contrast measures which control for more basic functions. The purpose of the present study was to examine whether difficulties related to inhibition and set-shifting in adult ADHD patients could be revealed by the Color Word Interference Test (CWIT) from the Delis Kaplan Executive Function System (D-KEFS). A clinically recruited group of adults with ADHD (n = 60) obtained significantly lower scores than population derived controls (n = 60) on both primary summary (p < .001) and contrast measures (p = .004) of set-shifting. The differences between the groups remained statistically significant after controlling for intellectual function and working memory (p = .003). However, no significant differences between the groups were observed on any measure of inhibition. The study indicates that adults with ADHD have specific difficulties with set-shifting as measured by the CWIT, difficulties that probably also reflect problems related to executive function in their daily life.

Neurophysiological correlates of delinquent behaviour in adult subjects with ADHD

The attention deficit/hyperactivity disorder (ADHD) shows an increased prevalence in arrested offenders compared to the normal population. The aim of the present study was to investigate whether ADHD symptoms are a major risk factor for criminal behaviour, or whether further deficits, mainly abnormalities in emotion-processing, have to be considered as important additional factors that promote delinquency in the presence of ADHD symptomatology. Event related potentials (ERPs) of 13 non-delinquent and 13 delinquent subjects with ADHD and 13 controls were compared using a modified visual Go/Nogo continuous performance task (VCPT) and a newly developed version of the visual CPT that additionally requires emotional evaluation (ECPT). ERPs were analyzed regarding their topographies and Global Field Power (GFP). Offenders with ADHD differed from non-delinquent subjects with ADHD in the ERPs representing higher-order visual processing of objects and faces (N170) and facial affect (P200), and in late monitoring and evaluative functions (LPC) of behavioural response inhibition. Concerning neural activity thought to reflect the allocation of neural resources and cognitive processing capability (P300 Go), response inhibition (P300 Nogo), and attention/expectancy (CNV), deviances were observable in both ADHD groups and may thus be attributed to ADHD rather than to delinquency. In conclusion, ADHD symptomatology may be a risk factor for delinquency, since some neural information processing deficits found in ADHD seemed to be even more pronounced in offenders with ADHD. However, our results suggest additional risk factors consisting of deviant higher-order visual processing, especially of facial affect, as well as abnormalities in monitoring and evaluative functions of response inhibition.

Effect size of lisdexamfetamine dimesylate in adults with attention-deficit/hyperactivity disorder

OBJECTIVE

To examine duration of efficacy of lisdexamfetamine dimesylate (LDX) in adults with attention-deficit/hyperactivity disorder (ADHD) by effect size in performance and symptom improvement in a simulated adult workplace environment (AWE).

METHODS

Adults (aged 18-55 years) with ADHD enrolled in the AWE study of LDX with open-label dose-optimization and randomized, placebo-controlled, double-blind, 2-way crossover phases. Efficacy measures included the Permanent Product Measure of Performance (PERMP)-Attempted (-A) and PERMP-Correct (-C) scores assessed throughout the day and the ADHD Rating Scale IV (ADHD-RS-IV) with adult prompts. Model-based least-squares (LS) mean effect size was assessed for PERMP and post-hoc ADHD-RS-IV with adult prompts. Remission was defined as an ADHD-RS-IV total scores ≤ 18. Safety assessments included treatment-emergent adverse events (TEAEs) and vital signs.

RESULTS

Least-squares mean (standard error [SE]) effect sizes were 0.9 (0.17) for PERMP-A and 0.8 (0.16) for PERMP-C for all postdose sessions. For PERMP-A, postdose LS mean (SE) effect sizes were 0.5 (0.15), 0.8 (0.16), 0.7 (0.16), 0.7 (0.16), 0.7 (0.16), and 0.6 (0.16) at 2, 4, 8, 10, 12, and 14 hours, respectively. Medium-to-large effect sizes (0.5-0.8) were generally maintained from 2 to 14 hours for all PERMP assessments. Overall LS mean (SE) ADHD-RS-IV total and subscale effect sizes were -1.2 (0.19), -1.2 (0.19), and -1.0 (0.17), respectively. Remission was achieved in 67.6% of participants receiving LDX. Treatment-emergent adverse events (≥ 5% with LDX) during the 4-week dose-optimization phase were decreased appetite, dry mouth, headache, insomnia, upper respiratory tract infection, irritability, nausea, anxiety, and feeling jittery. During the crossover week on LDX, there were no TEAEs ≥ 5%.

CONCLUSIONS

In adults studied in the AWE, medium-to-large model-based effect sizes were maintained from 2 to 14 hours postdose, on a performance-based measure of productivity, suggesting participants experienced improvement in sustained attention throughout the day and into the evening hours. Lisdexamfetamine dimesylate demonstrated a safety profile consistent with long-acting stimulants.

Are cognitive deficits in attention deficit/hyperactivity disorder related to the course of the disorder? A prospective controlled follow-up study of grown up boys with persistent and remitting course

To investigate the longitudinal course of cognitive functions in boys with persistent and remittent attention deficit/hyperactivity disorder (ADHD) from childhood into young adult years. Males (n=217) 15-31 years with and without ADHD were assessed at 3 time points over 10 years into young adulthood. Subjects were stratified into Remittent ADHD, and Persistent ADHD based on the course of ADHD. Cognitive domains included: 1) overall IQ (overall IQ, block design IQ, vocabulary IQ); 2) achievement scores in reading and math and measures of executive function (Wechsler arithmetic, digit span, digit symbol, Rey-Osterrieth, Wisconsin Card Sorting Test, and the Stroop Test). Cognitive outcomes were modeled as a function of group (Controls, Remittent ADHD, and Persistent ADHD), age, group by age interaction, and any demographic confounders using linear growth-curve models. There were no significant interaction effects of group by time. Main group effects indicated that persistent and remittent ADHD groups both had significantly lower scores on all cognitive outcomes compared with controls, and these did not differ between the ADHD subgroups Psychometrically defined cognitive deficits are relatively stable into young adult years and appear to be independent of the course of ADHD. More work is needed to help define the implications of these deficits in individuals with a remitting course of ADHD.

Adult Attention Deficit Hyperactivity Disorder Identified by Neuropsychological Testing

The authors used neuropsychological tests to assess and classify adult patients with attention deficit hyperactivity disorder (ADHD) and controls. Four memory tests correctly classified 81% of subjects. The memory tests were: the auditory Consonant trigram test, the Benton Visual Retention test, the Rey Auditory Verbal Learning test, and the modified Diagnosticum für Cerebralschädigung. The patients scored lower than controls also in other tests sensitive to frontal lobe dysfunction. The results underpin the importance of neuropsychological testing in adult ADD, but also support notions of a working-memory deficit linked to a dysfunction in the prefrontal cortex in these patients.

Once-daily medications for the pharmacological management of ADHD in adults

Attention-deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed psychiatric disorder in children and adolescents. Symptoms of ADHD often persist beyond childhood and present significant challenges to adults. Pharmacotherapy is a first-line treatment option for ADHD across all age groups. The current review's goals are (a) to critically examine the current state of knowledge regarding once-daily formulations of pharmacotherapies for treatment of adults with ADHD and (b) to provide clinicians with evidence-based information regarding the safety, efficacy and tolerability of once-daily medications for adult ADHD. The reviewed body of evidence strongly supports the use of pharmacotherapy as a first-line therapeutic option for the treatment of adults with ADHD. The once-daily pharmacological agents are effective therapeutic options for the treatment of adults with ADHD. In the US, based on the available evidence, once-daily medications are currently underutilized in adults with ADHD compared to pediatric population.

Management of attention-deficit hyperactivity disorder in adults: focus on methylphenidate hydrochloride

Attention-deficit hyperactivity disorder (ADHD) is one of the most common psychiatric disorders in young adults and causes significant psychosocial impairment and economic burden to society. Because of the paucity of long-term evidence and lack of national guidelines for diagnosis and management of adult ADHD, most of the data are based on experience derived from management of childhood ADHD. This article reviews the current evidence for the diagnosis and management of adult ADHD with special emphasis on the role of methylphenidate hydrochloride preparations in its treatment. Methylphenidate hydrochloride, a stimulant that acts through the dopaminergic and adrenergic pathways, has shown more than 75% efficacy in controlling the symptoms of adult ADHD. Although concern for diversion of the drug exists, recent data have shown benefits in preventing substance use disorders in patients with adult ADHD.

Reduced lateral prefrontal activation in adult patients with attention-deficit/hyperactivity disorder (ADHD) during a working memory task: a functional near-infrared spectroscopy (fNIRS) study

Near-infrared spectroscopy (NIRS) is an optical imaging method, which allows non-invasive in vivo measurements of changes in the concentration of oxygenated (O2Hb) and deoxygenated (HHb) haemoglobin in cortical tissue. For the present study, we examined 13 adult ADHD patients and 13 age- and gender-matched healthy controls by means of multi-channel NIRS (Optical Topography; ETG-100, Hitachi Medical Co., Japan) during performance of a working memory (n-back) paradigm. Compared to the healthy control group, ADHD patients showed reduced task-related increases in the concentration of O2Hb in NIRS channels located over the ventro-lateral prefrontal cortex, indicating reduced activation during performance of the n-back task in this part of the brain. This finding was particularly apparent for the task condition with high working memory load (2-back), and was accompanied by a statistical trend towards an increased number of omission errors in the patient group. The data confirm previous findings of working memory deficits and prefrontal cortex dysfunction in patients suffering from ADHD, and are discussed in the light of imaging findings and theoretical models of working memory function.

Women and attention deficit disorders: a great burden overlooked

PURPOSE

To describe adult attention-deficit/hyperactivity disorder (ADHD) in relation to gender-based differences in symptom expression with particular emphasis on disparities concerning women, psychiatric comorbidities that affect assessment and detection, and evidenced-based treatment approaches for nurse practitioners (NPs).

DATA SOURCES

Health sciences literature was reviewed using the following data-bases: Medline, Cumulative Index to Nursing and Allied Health Literature, PubMed, Proquest, Psych Info, Wiley Interscience, Cambridge Press, Science Direct, and Thomson Gale.

CONCLUSIONS

Recognizing adult ADHD may be challenging; however, with increased understanding regarding the subtle variations in symptoms, use of screening instruments, and careful assessment techniques, NPs will be better able to recognize the characteristics of ADHD that are important to early detection, proper diagnosis, and effective treatment.

IMPLICATIONS FOR PRACTICE

Additional research and improved clinician education may facilitate early detection and treatment of ADHD among adults of all ages and ethnic/racial backgrounds.

Stability of executive function deficits in girls with ADHD: a prospective longitudinal followup study into adolescence

Neuropsychological deficits in the executive system are major sources of morbidity in individuals with attention-deficit/hyperactivity disorder (ADHD). We conducted a 5-year longitudinal study of girls with (N = 140) and without (N = 122) ADHD, aged 6-18 years at baseline. Neuropsychological functioning was assessed using standard neuropsychological testing assessing executive functions (EFs). Girls with ADHD were significantly more impaired than controls in all neuropsychological domains except set shifting. Despite variability in the stability of individual domains of EFs, the majority (79%) of girls with ADHD that met the categorical definition of executive function deficits (EFDs, defined as two or more EF tasks impaired) at baseline continued to have EFDs at the five-year followup. These findings document the stability of EFDs in girls with ADHD from childhood into adolescence.

Effects of diagnostic comorbidity and dimensional symptoms of attention-deficit–hyperactivity disorder in men with antisocial personality disorder

OBJECTIVE

Although children with attention deficit hyperactivity disorder (ADHD) are at increased risk for later onset of antisocial personality disorder (APD) as adults, the utility of ADHD as either a comorbid diagnosis (ADHD(c)) or dimensional symptoms (ADHD(d)) in predicting behaviour and substance use problems in APD subjects has not been examined.

METHOD

A total of 105 adult male offenders with Structured Clinical Interview for Axis II Disorders (SCID-II)-based DSM-III-R APD were studied in terms of: (i) psychopathy scores on the Hare Psychopathy Checklist-Revised (PCL-R); (ii) ADHD(c) diagnostic comorbidity on clinically administered DSM-IV questionnaire; and (iii) ADHD(d) dimensional symptoms by means of Wender Utah Rating Scale (WURS) and Conners Adult ADHD Rating Scale (CAARS) during a 12 month study period (May 2005-May 2006).

RESULTS

Sixty five per cent of APD subjects met criteria for ADHD(c) diagnostic comorbidity with significantly increased rates of childhood neglect, parental divorce and suicide attempt, but not of psychopathy. APD subjects with ADHD(d) symptoms were noted to have earlier onset and increased rate of self-injurious behaviour (SIB), suicide attempt, and psychopathy. The psychopathy scores, in turn, were predictive of earlier onset of SIB and behavioural problems.

CONCLUSION

Both ADHD(c) diagnostic comorbidity and ADHD(d) symptoms need to be assessed in APD subjects and the dimensional measures may be better in detecting earlier onset SIB, suicide attempt and other behavioural problems.

Attention Deficit/Hyperactivity Disorder in Adults

Attention deficit/hyperactivity disorder (ADHD), characterized by inattention, hyperactivity/impulsivity, or a combination of these, is being increasingly recognized in adults. Adult ADHD prevalence rates range from 1% to 4%. The pathophysiology of adult ADHD is likely multifactorial, including genetic, environmental, and neurobiological influences. Though ADHD diagnostic criteria per the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) were developed based on child samples, the symptoms are believed to be similar in adults, with some developmental differences in symptom presentation. This article identifies common presenting complaints of adults who have ADHD and provides information useful for differential diagnosis of these patients. Specific strategies for pharmacological and nonpharmacological intervention are also presented.

Attention-deficit/hyperactivity disorder: a neuropsychological perspective towards DSM-V

Neuropsychological methods and techniques have much to offer in the evaluation of the individual suspected as having Attention-Deficit/Hyperactivity Disorder (ADHD). After a review of the historical evolution of the ADHD concept, incidence and prevalence, and DSM-IV criteria for diagnosis, especially as regards omission related to gender differences, and other associated cultural, familial, socioenvironmental, and subject influences, this paper describes a number of dilemmas and obstacles encountered in clinical practice. Included are the confounds associated with the wide range of possible comorbidities, the insufficiency of current DSM-IV criteria, the emergence of subtype differentiation and its impact on diagnosis and treatment. The complex relationship between neuropsychological constructs and ADHD, and obstacles to valid assessment are also addressed. The complexities associated with a thorough ADHD evaluation are viewed within an impressive and expansive existing scientific framework and recommendations are made for future directions.

Stability of executive function deficits into young adult years: a prospective longitudinal follow-up study of grown up males with ADHD

OBJECTIVE

Although individuals with attention deficit-hyperactivity disorder (ADHD) commonly exhibit deficits in executive functions that greatly increase the morbidity of the disorder, all available information on the subject is cross sectional.

METHOD

Males (n = 85) 9-22 years with ADHD followed over 7 years into young adulthood were assessed on measures of sustained attention/vigilance, planning and organization, response inhibition, set shifting and categorization, selective attention and visual scanning, verbal and visual learning, and memory. A binary definition of executive function deficits (EFDs) was defined based on a subject manifesting at least two abnormal tests 1.5 standard deviations from controls.

RESULTS

The majority of subjects maintained EFDs over time (kappa: 0.41, P < 0.001; sensitivity: 55%, specificity: 85%, positive predictive value: 69%, and negative predictive value: 75%).

CONCLUSION

Considering the morbidity of EFDs, these findings stress the importance of their early recognition for prevention and early intervention strategies. EFDs are stable over time.

Association between response inhibition and working memory in adult ADHD: a link to right frontal cortex pathology?

BACKGROUND

We sought to assess the relationship between response inhibition and working memory in adult patients with attention-deficit/hyperactivity disorder (ADHD) and neurosurgical patients with frontal lobe damage.

METHODS

The stop-signal reaction time (SSRT) test and a spatial working memory (SWM) task were administered to 20 adult patients with ADHD and a group of matched controls. The same tasks were administered to 21 patients with lesions to right frontal cortex and 19 patients with left frontal lesions.

RESULTS

The SSRT test, but not choice reaction time, was significantly associated with search errors on the SWM task in both the adult ADHD and right frontal patients. In the right frontal patients, impaired performance on both variables was correlated with the volume of damage to the inferior frontal gyrus.

CONCLUSIONS

Response inhibition and working memory impairments in ADHD may stem from a common pathologic process rather than being distinct deficits. Such pathology could relate to right frontal-cortex abnormalities in ADHD, consistent with prior reports, as well as with the demonstration here of a significant association between SSRT and SWM in right frontal patients.

A clinical construct validity study of a novel computerized battery for the diagnosis of ADHD in young adults

The cognitive profile of adult attention deficit hyperactivity disorder (ADHD) remains understudied despite difficulty in diagnosis. Further, no battery of neuropsychological tests has been shown valid in adult ADHD. Continuous performance tests are widely used for ADHD but provide limited information on cognitive functioning in general. The present study evaluated the construct and discriminant validity of Mindstreams (NeuroTrax Corp., NY), a computerized battery assessing multiple cognitive domains. Twenty-nine young male adults with ADHD diagnosis completed a Mindstreams battery, including a multi-stage continuous performance ('Expanded Go-NoGo') test, and the Conners' CPT-II (Multi-Health Systems Inc., NY). Discriminant validity was assessed by comparisons with cognitively healthy controls of comparable age and education. Expanded Go-NoGo and corresponding CPT-II outcomes were significantly correlated in ADHD participants, and the Expanded Go-NoGo test exhibited excellent discriminant validity, with ADHD participants performing more poorly than controls. ADHD participants also performed more poorly on Stroop and Staged Information Processing Speed tests.

Can self-reported behavioral scales assess executive function deficits? A controlled study of adults with ADHD

One of the suspected sources of negative outcomes associated with attention-deficit/hyperactivity disorder (ADHD) has been a deficit in executive functions (EFD). Although self-report questionnaires purport to assess behavioral concomitants of EFDs, little is known about their informativeness. The aim was to examine the association between self-reported behavioral concomitants of EFDs and functional outcomes among adults with ADHD. Subjects were adults with (N = 200) and without (N = 138) DSM-IV criteria for ADHD. The Current Behavior Scale (CBS) was used as a proxy for EFDs. The 50th percentile of the ADHD subjects' total CBS scores explained the most variance in the functional outcomes compared with other cutoffs, and it identified subjects with more impaired global functioning, more comorbidities, and lower socioeconomic status. Scores on the CBS above the 50th percentile identify adults with ADHD at significantly higher risk for functional morbidity beyond that conferred by the diagnosis of ADHD alone.

Evidence-based guidelines for management of attention-deficit/hyperactivity disorder in adolescents in transition to adult services and in adults: recommendations from the British Association for Psychopharmacology

Attention-deficit/hyperactivity disorder (ADHD) is an established diagnosis in children, associated with a large body of evidence on the benefits of treatment. Adolescents with ADHD are now leaving children's services often with no readily identifiable adult service to support them, which presents problems as local pharmacy regulations often preclude the prescription of stimulant drugs by general practitioners (GPs). In addition, adults with ADHD symptoms are now starting to present to primary care and psychiatry services requesting assessment and treatment. For these reasons, the British Association for Psychopharmacology (BAP) thought it timely to hold a consensus conference to review the body of evidence on childhood ADHD and the growing literature on ADHD in older age groups. Much of this initial guidance on managing ADHD in adolescents in transition and in adults is based on expert opinion derived from childhood evidence. We hope that, by the time these guidelines are updated, much evidence will be available to address the many directions for future research that are detailed here.

Working memory deficits in adults with ADHD: is there evidence for subtype differences?

BACKGROUND

Working memory performance is important for maintaining functioning in cognitive, academic and social activities. Previous research suggests there are prevalent working memory deficits in children with attention deficit hyperactivity disorder (ADHD). There is now a growing body of literature characterizing working memory functioning according to ADHD subtypes in children. The expression of working memory deficits in adults with ADHD and how they vary according to subtype, however, remains to be more fully documented.

METHODS

This study assessed differences in working memory functioning between Normal Control (NC) adults (N = 18); patients with ADHD, Combined (ADHD-CT) Type ADHD (N = 17); and ADHD, Inattentive (ADHD-IA) Type (N = 16) using subtests from the Wechsler Adult Intelligence Scale-III and Wechsler Memory Scale-III and the Paced Auditory Serial Addition Task (PASAT).

RESULTS

The ADHD groups displayed significant weaknesses in contrast to the NC group on working memory tests requiring rapid processing and active stimulus manipulation. This included the Letter-Number-Sequencing test of the Wechsler scales, PASAT omission errors and the longest sequence of consecutive correct answers on the PASAT. No overall ADHD group subtype differences emerged; however differences between the ADHD groups and the NC group varied depending on the measure and the gender of the participants. Gender differences in performance were evident on some measures of working memory, regardless of group, with males performing better than females.

CONCLUSION

In general, the data support a dimensional interpretation of working memory deficits experienced by the ADHD-CT and ADHD-IA subtypes, rather than an absolute difference between subtypes. Future studies should test the effects of processing speed and load on subtype performance and how those variables interact with gender in adults with ADHD.