Neuropsychological testing in adult attention deficit hyperactivity disorder: a pilot study

Conner's Continuous Performance Test and Adult ADHD: A Systematic Literature Review

OBJECTIVE

ADHD is a neurodevelopmental disorder affecting millions of adults worldwide. Continuous performance tests (CPTs) are widely used as assessment and diagnostic tools; however, their use in diagnosing undiagnosed ADHD in adults has been questioned due to their lack of specificity and sensitivity. This review sought to outline relevant findings concerning the diagnostic utility of the Conner's Continuous Performance Test (CCPT) in adults.

METHOD

This systematic review followed the a priori guide outlined by the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. Articles were gathered from PsycINFO, PsycArticles, Cochrane, Scopus, Google Scholar, and PubMed.

RESULTS

Thirty-five articles were reviewed and analyzed. Most articles reviewed used outpatient and university populations. Moderate reliability, subpar discriminant and ecological validity, and mixed sensitivity and specificity were noted.

CONCLUSION

The results of this review lend support to previous critiques of the CCPT's diagnostic and utility as a treatment measure.

Complexity analysis of fNIRS signals in ADHD children during working memory task

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder in children. Neuroimaging studies have revealed abnormalities of neural activities in some brain regions, including the frontal cortex, striatum, cerebellum, and occipital cortex. Recently, some investigators have demonstrated that nonlinear complexity analysis of neural activity may provide a new index to indicate ADHD. In the present study, we used the permutation entropy (PE) to measure the complexity of functional near-infrared spectroscopy (fNIRS) signals in children with and without ADHD during a working memory task, it was aimed to investigate the relationship between the PE values and the cortical activations, and the different PE values between the children with and without ADHD. We found that PE values exhibited significantly negative correlation with the cortical activations (r = -0.515, p = 0.003), and the PE values of right dorsolateral prefrontal cortex in ADHD children were significantly larger than those in normal controls (p = 0.027). In addition, the PE values of right dorsolateral prefrontal cortex were positively correlated to the ADHD index (r = 0.448, p = 0.012). These results suggest that complexity analysis of fNIRS signals could be a promising tool in diagnosing children with ADHD.

Neuropsychological Functioning in Adults With ADHD and Adults With Other Psychiatric Disorders

OBJECTIVE

The aim was to investigate how well neuropsychological measures can discriminate between adults with ADHD and those with other psychiatric disorders.

METHOD

Adults with ADHD and a clinical control group ( n = 110) were included. Neuropsychological functioning was investigated using measures of inhibition, working memory, set shifting, planning, fluency, reaction-time variability, and delay aversion.

RESULTS

Adults with ADHD performed more poorly compared with clinical controls with regard to all constructs. The effects of verbal memory, inhibition, set shifting, fluency, and delay aversion remained significant when controlling for IQ. However, when controlling for basic cognitive functions, only the effects of inhibition, fluency, and delay aversion were significant. Sensitivity ranged between 64% and 75%, and specificity between 66% and 81%.

CONCLUSION

Neuropsychological tests have a relatively poor ability to discriminate between adults with ADHD and clinical controls, but they may be used to identify individuals at particularly high risk for poor daily functioning.

Postsecondary ADHD Documentation Requirements: Common Practices in the Context of Clinical Issues, Legal Standards, and Empirical Findings

OBJECTIVE

To evaluate the information postsecondary institutions require when determining disability service eligibility for students with reported ADHD.

METHOD

ADHD documentation requirements of 200 U.S. institutions were surveyed by reviewing guidelines posted on disability services websites.

RESULTS

Whereas virtually all institutions required documentation, findings revealed significant variability in requirements across institutions. Required variables most often included a qualified evaluator (80%), diagnostic statement (75%), and identification of substantial limitations (73%), but only 5 of 46 evaluated variables were required by at least 50% of institutions. Supportive data such as diagnostic criteria, standardized assessment results, and rationale for accommodations were rarely required.

CONCLUSION

The majority of institutions required little to verify ADHD as a disability. Furthermore, there was little agreement on what components are essential for verification. When integrated with research, a large portion of guidelines failed to address identified weaknesses in ADHD diagnosis and disability determination.

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.

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.

A context for normalizing impulsiveness at work for adults with attention deficit/hyperactivity disorder (combined type)

Impaired executive function and impulsiveness or intolerance to boredom in adult attention deficit/hyperactivity disorder (ADHD) are thought to compromise performance at work. Several task parameters help people with ADHD to perform better on computerized cognitive tasks, namely reduced response-to-stimulus interval, discriminative feedback, or a format resembling a videogame. However, still very little is known about how these contexts might be helpful in a real work environment. We developed a computerized task resembling a fast-paced videogame with no response-to-stimulus interval and constant and diverse discriminative error feedback. The task included several measurements of high-order executive function (planning, working memory, and prospective memory) formatted as a single multitask simulating occupational activities (SOA). We also administered the Continuous Performance Test-II (CPT-II), a very simple vigilance task without discriminative feedback and with long response-to-stimulus intervals. We tested 30 adults answering to DSM-IV criteria of ADHD (combined type) and 30 IQ-matched adults without ADHD. As has been reported many times, the ADHD participants made significantly more errors of commission than the control participants on the CPT-II, whereas the two groups made the same number of errors of commission on the SOA. The ADHD group also sought discriminative feedback significantly more actively on the SOA than the control group and performed at par with the control group in all respects. There was no speed/accuracy trade-off, nor was there any evidence of other costs of normalization on the SOA. Impulsiveness in adult ADHD is compensable on a task simulating the work environment.

Differential effects of methylphenidate on problem solving in adults with ADHD

OBJECTIVE

Two studies were performed to assess both divergent and convergent thinking in adults with ADHD.

METHOD

The first study compared the problem-solving abilities of healthy participants (N = 144) and unmedicated adults with ADHD (N = 144). In the second study, problem-solving abilities of adults with diagnosed ADHD (N = 22) were examined twice, that is, on and off methylphenidate (MPH), and compared with the performance of a healthy control group (N = 22). Convergent thinking was measured using a Tower of London task, whereas divergent thinking was assessed using verbal fluency tasks.

RESULTS

Adults with ADHD off MPH displayed marked deficits of both divergent and convergent thinking. MPH treatment resulted in a marked improvement of convergent thinking, while no effect of medication was found regarding divergent thinking.

CONCLUSION

Pharmacological treatment of adults with ADHD revealed a differential effect of MPH on problem solving abilities.

A verbal planning impairment in adult ADHD indexed by script generation tasks

OBJECTIVE

Though juvenile and adult ADHD cases are well known to have a nonverbal planning impairment, a verbal-planning impairment has been demonstrated only in juvenile ADHD. The purpose of this investigation is to determine whether a verbal planning impairment also characterizes adult ADHD.

METHODS

A cohort of 30 adult ADHD clients of a university psychological clinic are compared to 30 age-, education-, gender-, and IQ-matched persons recruited from the general population who did not have ADHD. The dependent measure is a set of 6 paper/pencil 10-item script generation tasks.

RESULTS

The findings reveal that the ADHD cohort was significantly impaired on the script task and the script task correlated significantly with severity of ADHD (CAARS index + WURS), whereas several neuropsychological measures of executive function (Stroop, COWA, Rey's Complex Figure, D2, CVLT, CPT-II) did not. Findings further showed that the script measure was weakly correlated with the other established neuropsychological measures of executive function (r < .46, shared variance of less than 21%).

CONCLUSIONS

On the basis of the study findings, it is concluded that verbal planning measured with script generation tasks is distinctly impaired in clinically referred adult 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.

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.

Neuropsychological functioning in people with ADHD across the lifespan

ADHD is defined by behavioral characteristics similar to neuropsychological disorders of executive dysfunction. This paper is a literature review of the neurocognitive characteristics of ADHD from early childhood through adulthood. The author addresses the development of the concept of attention and executive function (EF) deficits in ADHD, clinical neuropsychological studies of pre-teenage children, teenagers and adults with ADHD, gender and the role of psychiatric co-morbidity including the relationship of learning disabilities to ADHD, heterogeneity of neuropsychological dysfunctions, experimental neuropsychological studies, the relationship of brain structure to function, psychopharmacology of ADHD, and clinical neuropsychological assessment. The group data clearly supports the hypothesis that executive dysfunctions are correlates of ADHD regardless of gender and age, and these EF deficits are exacerbated by co-morbidity with learning disabilities such as dyslexia. However, there is limited data on children under the age of 5, teenagers from age 13-18, and adults with ADHD over the age of 40. Studies of individual classification of people with ADHD compared to healthy, non-psychiatric controls do not support the use of neuropsychological tests for the clinical diagnosis of ADHD, and indicate that not all persons with ADHD have EF deficits. Some persons with ADHD may have deficits in brain reward systems that are relatively independent of EF impairments. Future research should clarify the multiple sources of ADHD impairments, continue to refine neuropsychological tools optimized for assessment, and incorporate longitudinal, developmental designs to understand ADHD across the lifespan.

Relationship of the Wender Utah Rating Scale to objective measures of attention

The Wender Utah Rating Scale (WURS) is a 25-item self-report questionnaire for the retrospective assessment of childhood attention-deficit hyperactivity disorder (ADHD) symptoms; high scores indicate greater symptoms. The current study used 35 male Veterans Affairs outpatients to determine if WURS scores were associated with objective measures of current attentional functioning, including the Trail Making Test, Gordon Diagnostic System, Wechsler Adult Intelligence Scale-Revised digit span and digit symbol subtests, and Wechsler Memory Scale-Revised mental control subtest. Participants included both adults diagnosed with ADHD (n = 14) and non-ADHD adults (n = 21). After Bonferroni correction, Pearson product moment correlation coefficients revealed that greater symptoms on the WURS were associated with poorer digit symbol performance (r = -0.69, P < .05). To determine which indices best predicted WURS scores, scores on attention tests and demographic variables were entered into a stepwise multiple regression analysis. Digit symbol performance was the only significant predictor of WURS scores (R(2) = 0.59, P < .01). Thus, poor performance on a sensitive, but nonspecific, measure of attention with executive function, response speed, and visuomotor coordination components was related to greater self-report of childhood ADHD symptoms.

Atomoxetine and stroop task performance in adult attention-deficit/hyperactivity disorder

OBJECTIVE

The aim of this study was to assess the efficacy of atomoxetine, a new and highly selective inhibitor of the norepinephrine transporter, for executive functioning in adults with attention-deficit/hyperactivity disorder (ADHD).

METHOD

Two identical studies using a double-blind, placebo-controlled, parallel design were conducted. Patients were adults (Study 1, n = 280; Study 2, n = 256) with Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV)-defined ADHD recruited by referral and advertising. They were randomized to 10 weeks of treatment with atomoxetine or placebo. Executive functions were measured by the Stroop task.

RESULTS

There was no evidence of cognitive deterioration associated with atomoxetine treatment. Atomoxetine treatment was associated with an improvement of the Stroop colorword score.

CONCLUSIONS

Our results provide further support for Spencer et al.'s (1998) report that atomoxetine improves inhibitory capacity, as measured by the Stroop task. The absence of cognitive deterioration from atomoxetine, along with improved performance in a subgroup of patients in this large study, supports the safety of atomoxetine in this regard and its potential for improving a significant source of impairment for adults with ADHD.

Functional neuroanatomy of working memory in adults with attention-deficit/hyperactivity disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) in adults is an increasingly recognized psychiatric disorder, linked with impairments in numerous life domains and with neurocognitive dysfunctions. However, the neural substrate of cognitive functioning in adults with this disorder has been relatively unexamined. The objective of this study was to examine neural functioning in ADHD adults during performance on a verbal working memory task.

METHODS

A sample of unmedicated adults with ADHD (n = 20) and control subjects (n = 20) performed a 2-back task of working memory, and the blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) response was used as a measure of neural activity during working memory performance.

RESULTS

Though working memory performance did not differ significantly between ADHD adults and control subjects, ADHD adults showed significantly decreased activity in cerebellar and occipital regions and a trend toward decreased activation in an a priori predicted region of the prefrontal cortex.

CONCLUSIONS

ADHD adults showed altered patterns of neural activity despite comparable performance on a verbal working memory task. These findings suggest that the cerebellum is involved in the pathophysiology of at least some cognitive deficits associated with ADHD and emphasize the need for additional research aimed at elucidating the role of the cerebellum in ADHD symptomatology.

Effect of methylphenidate on executive functioning in adults with attention-deficit/hyperactivity disorder: normalization of behavior but not related brain activity

BACKGROUND

We examined the effect of prolonged methylphenidate (MPH) treatment on the functional neuroanatomy of executive functioning in adult men with attention-deficit/hyperactivity disorder (ADHD).

METHODS

Positron emission tomography with [(15)O] water measured alterations of regional cerebral blood flow (rCBF) during the Paced Auditory Serial Addition Task and a control task in 10 ADHD and 11 normal control men. Attention-deficit/hyperactivity disorder men were imaged unmedicated and after a clinically optimal dose of MPH for 3 weeks.

RESULTS

Methylphenidate improved ADHD task performance, reduced rCBF in the prefrontal cortex (PFC), and increased rCBF in the right thalamus and precentral gyrus. Comparisons between the ADHD and normal control groups showed that normal control participants exhibited greater anterior cingulate cortex and temporal gyrus rCBF than ADHD participants under both conditions. Executive functioning was associated with greater subcortical (basal ganglia and cerebellar vermis) activation in the ADHD than normal control group under both conditions.

CONCLUSIONS

Methylphenidate does not normalize task-related activity in ADHD. Task-related rCBF decreases in the PFC may be due to improved filtering out of task-irrelevant stimuli by way of MPH-mediated dopamine release in the PFC.

Neuropsychology of adults with attention-deficit/hyperactivity disorder: a meta-analytic review

A comprehensive, empirically based review of the published studies addressing neuropsychological performance in adults diagnosed with attention-deficit/hyperactivity disorder (ADHD) was conducted to identify patterns of performance deficits. Findings from 33 published studies were submitted to a meta-analytic procedure producing sample-size-weighted mean effect sizes across test measures. Results suggest that neuropsychological deficits are expressed in adults with ADHD across multiple domains of functioning, with notable impairments in attention, behavioral inhibition, and memory, whereas normal performance is noted in simple reaction time. Theoretical and developmental considerations are discussed, including the role of behavioral inhibition and working memory impairment. Future directions for research based on these findings are highlighted, including further exploration of specific impairments and an emphasis on particular tests and testing conditions.

The utility of self-report measures and the continuous performance test in the diagnosis of ADHD in adults

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) occurs in as many as 4 percent of adults yet it is often not recognized in clinical settings because the presenting symptoms may resemble those seen in other disorders or because symptoms may be masked by commonly comorbid conditions such as anxiety and depression.

OBJECTIVE

The purpose of this study was to examine the diagnostic utility of instruments commonly used in the assessment of adults presenting with symptoms of ADHD.

METHODS

We reviewed several widely used self-report and laboratory measures and empirically examined the utility of the Brown Attention-Deficit Disorder Scale for Adults (Brown ADD Scale) and the Conners Continuous Performance Test (CPT) in differentially identifying adults with ADHD and those with other Axis I disorders.

RESULTS

Ninety-three adults who self-referred to the ADHD program for adults at a university medical center participated in the study. Of these, 44 had ADHD combined subtype (ADHD-CB), and 26 had ADHD, predominantly inattentive subtype (ADHD-IA). Thirty-three non-ADHD adults diagnosed with Axis I mood or anxiety disorders comprised an "Other Psychiatric" group. Rates of comorbid disorders, including substance abuse, in the ADHD groups were typical of those reported in the adult ADHD literature. Data on the Brown ADD Scale and on the CPT were available for subsets of 61 and 46 participants, respectively. Analyses showed that the ADHD-CB, ADHD-IA, and Other Psychiatric groups all received mean scores in the clinical range on the Brown ADD Scale, with a trend toward even higher elevations in the two ADHD groups. Among 12 CPT variables assessed for the three groups, the mean scores on only two variables for the ADHD-IA group were clinically elevated. Neither the Brown ADD Scale nor CPT scores evinced sufficient sensitivity and specificity to qualify them to assist in differential diagnosis of ADHD vis-a-vis other, predominantly internalizing, psychiatric disorders.

CONCLUSION

The results indicate a need for closer examination of executive and adaptive functioning in adults with ADHD compared with those with internalizing disorders in order to identify features that could assist in differential diagnosis.

Self-report and objective measures of ADHD-related behaviors in parents of preschool children at risk for ADHD

OBJECTIVE

Few studies have used a combination of objective and self-report measures to examine neuropsychological and behavioral functioning in parents of children with attention-deficit/hyperactivity disorder (ADHD). This study examined attention and inhibitory control in the parents of preschool children who were rated as "at risk" for developing ADHD as compared with parents of controls.

METHODS

Preschool children (N=53) were divided into at risk for ADHD and control groups based on parent and teacher ratings of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition ADHD symptoms. One parent of each child was administered an identical pairs Continuous Performance Test (CPT-IP), a Go/No-Go task, and the Brown Attention-Deficit Disorder Scale for Adults.

RESULTS

Parents of preschoolers at risk for ADHD showed a pattern of responding on measures of vigilance characterized by slower reaction times and increased commission errors as compared with parents of controls. There were no significant group differences on self-report measures on the Brown Attention-Deficit Disorder Scale for Adults.

CONCLUSION

Parents of preschoolers at risk for ADHD appear to exhibit cognitive processing deficits that may not be evident using self-report measures. Further research is needed to more clearly identify the specific nature of these neuropsychological deficits and to determine whether they have a negative impact on their children.

Neuropsychological function in adults with attention-deficit/hyperactivity disorder

This article reviews the current state of the literature pertaining to the neuropsychological dysfunctions that are found in children and adults with attention-deficit/hyperactivity disorder (ADHD). Be-cause considerable controversy has existed about the nature and validity of adult ADHD, this article will aid clinicians in develop-ing a better understanding of the empirical literature on neuropsychological function in ADHD throughout the lifespan.

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

The recognition of attention deficit/hyperactivity disorder (ADHD) in adults is a well documented, but relatively new development. Investigations of the disorder have indicated that disturbances in behavior and adjustment are common. These disturbances may be linked to poorly developed executive functions. This paper reviews the neuropsychological studies that have compared persons with ADHD to normal controls and to psychiatric controls. The review indicates that persons with ADHD share many neuropsychological characteristics with other persons with serious psychiatric conditions, although those with ADHD may have a particular profile of slowed performance in tasks of sustained attention and set shifting, and their use of working memory may be particularly impaired. The implications of research for clinical assessment are discussed. We contend that a neuropsychological orientation is necessary for making the diagnosis and gaining a full understanding of adult ADHD. A model for clinical assessment is proposed which utilizes a neuropsychological orientation and the targeted administration of neuropsychological instruments. The careful use of neuropsychological measures is warranted in providing an elaborate picture of a person's functioning, although the use of neuropsychological tests is not necessary to make the diagnosis.

Continuous performance tests are sensitive to ADHD in adults but lack specificity. A review and critique for differential diagnosis

Historically, the focus for Attention Deficit Hyperactivity Disorder (ADHD) has been on children, with considerable research and many opinions available in this area. More recently, the focus has been expanded to include ADHD in adults. Assessment of ADHD in adults is complicated by the high rate of co-occurring disorders as well as symptom overlap with a number of disorders. One popular family of measures for the assessment of attention and executive control is the continuous performance test (CPT). A review of the available research on CPTs reveals that they are quite sensitive to CNS dysfunction. This is both a strength and a limitation of CPTs in that multiple disorders can result in impaired performance on a CPT. The high sensitivity of CPTs is further complicated by the multiple variations of CPTs available, some of which may be more sensitive or demonstrate better specificity to ADHD in adults than others. If CPTs are to be used clinically, further research will be needed to answer the questions raised by this review.

Adult attention-deficit/hyperactivity disorder: neuropsychological correlates and clinical presentation

We compared the neuropsychological test performance of adult ADHD patients to the neurocognitive profiles of control subjects recruited from the general population. We administered a neuropsychological test battery consisting of measures considered sensitive to either orbitofrontal or dorsolateral-prefrontal (DLPF) dysfunction. Orbitofrontal hypoarousal is associated with behavioral disinhibition and a relative indifference to punishment. The DLPF region may function as a central executive system. Indeed, DLPF dysfunction may underlie many of the cardinal symptoms associated with ADHD. We tested the following hypotheses: (1) adult subjects meeting DSM-IV criteria for ADHD, predominantly hyperactive-impulsive type, would display neuropsychological deficits on tasks sensitive to orbitofrontal dysfunction; (2) adult subjects meeting DSM-IV criteria for ADHD, predominantly inattentive type, would perform poorly on measures sensitive to DLPF dysfunction; and (3) adult subjects meeting DSM-IV criteria for ADHD, combined type, would exhibit performance deficits on orbitofrontal measures and on DLPF tasks. Results partially confirmed our hypotheses. Subtyping ADHD patients revealed important group differences. Distinct neurocognitive and clinical profiles were observed.

Comparing guanfacine and dextroamphetamine for the treatment of adult attention-deficit/hyperactivity disorder

The objective of this study was to compare the efficacy of the alpha-2a agonist guanfacine with that of dextroamphetamine for the treatment of adult attention-deficit/hyperactivity disorder (ADHD). Seventeen adult outpatients who met DSM-IV criteria for ADHD participated in a double-blind, placebo-controlled, crossover study comparing drug effects on ADHD symptoms. Measures of change included the DSM-IV ADHD Behavior Checklist for Adults and the Copeland Symptom Checklist for Adult Attention Deficit Disorders. Cognitive measures of attention included the Stroop and Controlled Oral Word Association Test using the letters "C," "F," and "L" (COWAT, CFL version). For each trial, the drug was administered daily and titered up to optimal doses of maximum efficacy but with a minimum of side effects, and then data were collected. Both drugs significantly reduced ADHD symptoms on the DSM-IV Adult Behavior Checklist for Adults over placebo (p < 0.05). The Stroop Color subscale showed significant improvement for both drugs (p < 0.05), but the Color-Word measures showed significant improvement for guanfacine only (p < 0.01). The average dose of guanfacine was 1.10 (SD = 0.60), and the most common side effect of guanfacine was fatigue. No subjects discontinued drug trials. This preliminary study indicates that guanfacine may be a well-tolerated treatment option for adult ADHD.

Attention-deficit/hyperactivity disorder in adults: an overview

To assess the validity of adult attention-deficit/hyperactivity disorder (ADHD), we reviewed clinical, family, psychopharmacologic, neurobiological, and outcome studies. We found multiple reports describing adults with clinical features highly reminiscent of the childhood ADHD. These adults, who are impulsive, inattentive, and restless, have the clinical "look and feel" of ADHD children. As with their childhood counterparts, many adults with ADHD suffer from antisocial, depressive, and anxiety disorders. They also show clinically significant impairments--histories of school failure, occupational problems, and traffic accidents. Studies of biological features show correspondences between child and adult cases of ADHD. Both show familial aggregation and a characteristic profile of neuropsychologic deficits; an emerging neuroimaging literature suggests that abnormalities in the same brain regions underlie both the child and adult forms of the disorder. Although these converging lines of evidence support the validity of ADHD in adults, follow-up studies of ADHD children have yielded ambiguous results. This ambiguity is in part due to differences in how researchers define the persistence of ADHD, a problem that suggests future research focus on how best to diagnose ADHD in adulthood.

Neurocognitive functioning in adults with attention-deficit/hyperactivity disorder

The performance of nine adults with attention-deficit/hyperactivity disorder (ADHD) was compared with the performance of 23 normal controls on computerized measures of target orientation, sustained attention, encoding speed, and motor output/response organization to determine the nature of the neurocognitive deficits of adults with ADHD. While the groups' performances on measures of sustained attention and encoding speed did not differ, significant group differences were seen on a task that targeted motor output/response organization. These data suggest that the neurocognitive difficulties of ADHD adults are not related to a primary deficit in sustained attentional functioning. Rather, the deficient information processing in ADHD adults is related to difficulties with motor output/response organization.