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

Cognitive deficit in adults with ADHD lies in the cognitive state disorder rather than the working memory deficit: A functional near-infrared spectroscopy study

This study tested whether cognitive deficit in patients with adult attention deficit hyperactivity disorder (ADHD) is a working memory deficit or cognitive state disorder during the N-back task. Twenty-two adults with ADHD and twenty-four healthy controls participated in the N-back task. The functional near-infrared spectroscopy (fNIRS) was combined with three perspectives from behavioral and spatial and temporal activation characteristics of blood oxygen levels in the prefrontal cortex to examine the psychological and neuroprocessing characteristics of adult ADHD. Data were acquired using a block design during an N-back task with three memory loads. Visual stimuli were presented on a computer monitor. Behaviorally, response time and accuracy showed no significant differences between the two groups. Spatially, in the left orbitofrontal area and the left frontopolar area (Channels 4 and 11), adult ADHD had significantly higher activation levels of oxyHb in the 2-back task and lower activation levels of deoxyHb in the 3-back task than healthy controls (corrected p < 0.05). Therefore, Channel 4 in the 2-back condition and Channel 11 in the 3-back condition were used as the regions of interest (ROI). Temporally, adults with ADHD peaked earlier in the ROIs than healthy controls. Furthermore, working memory deficit was not found directly from the behavioral performance in adult ADHD. However, adult ADHD can be affected by memory load, task duration, and novelty stimulus. Our findings suggest that patients with adult ADHD have cognitive state disorder instead of working memory deficit.

Neuropsychological Deficits in Adult ADHD: Evidence for Differential Attentional Impairments, Deficient Executive Functions, and High Self-Reported Functional Impairments

Objective: This study is aimed to investigate neuropsychological deficits in adult ADHD. Method: Neuropsychological deficits in terms of executive functions, divided, selective, and sustained attention, were investigated in a group of adults with ADHD using a series of neuropsychological tests as well as electroencephalography (EEG). Subjective ratings of everyday life attention and memory problems were also collected. Results: Adults with ADHD showed impairments in executive functions, divided attention and sustained attention, compared with adult controls. Performance on selective attention tasks in adults with ADHD was instead no different from control participants' performance. EEG results confirmed neuropsychological findings by showing a selective impairment on P3 event-related potential (ERP) amplitude indicative of sustained attention deficits. Higher subjective ratings of everyday attentional and memory problems were also found in the ADHD group compared with the control group. Conclusion: This pattern of results suggests differential impairments of attentional skills. Impaired executive functions and higher subjective functional impairments were also found.

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.

Behavior Evaluation Based on Electroencephalograph and Personality in a Simulated Driving Experiment

Assessments and predictions of driving behavior are very important to improve traffic safety. We hypothesized that there were some patterns of driving behaviors, and these patterns had some correlation with cognitive states and personalities. To test this hypothesis, an evaluation of driving status, based on electroencephalography (EEG) and steering behavior in a simulated driving experiment, was designed and performed. Unity 3D was utilized to design the simulated driving scene. A photoelectric encoder fixed on the steering wheel and the corresponding data collection, transmission, and storage device was developed by Arduino, to acquire the rotation direction, angle, angular velocity, and angular acceleration of the steering wheel. Biopac MP 150 was utilized to collect the EEG data simultaneously during driving. A total of 23 subjects (mean age 23.6 ± 1.3 years, driving years: 2.4 ± 1.6 years, 21 males and two females) participated in this study. The Fuzzy C-means algorithm (FCMA) was utilized to extract patterns of driving behavior and the cognitive state within the window width of 20 s. The behaviors were divided into five kinds, i.e., negative, normal, alert, stress, and violent behavior, respectively, based on the standard deviation of steering wheel data. The cognitive states were divided into four kinds, i.e., negative, calm, alert, and tension, respectively, based on the EEG data. The correlation of these data, together with the personality traits evaluated using Cattell 16 Personality Factor Questionnaire (16PF) were analyzed using multiclass logistic regression. Results indicated the significance of the cognitive state and seven personality traits [apprehension (O), rule consciousness (G), reasoning (B), emotional stability (C), liveliness (F), vigilance (L), and perfectionism (Q3)] in predicting driving behaviors, and the prediction accuracy was 80.2%. The negative and alert cognitive states were highly correlated with dangerous driving, including negative and violent behaviors. Personality traits complicate the relationship with driving behaviors, which may vary across different types of subjects and traffic accidents.

Sustained attention in adult ADHD: time-on-task effects of various measures of attention

Neuropsychological research on adults with ADHD showed deficits in various aspects of attention. However, the majority of studies failed to explore the change of performance over time, so-called time-on-task effects. As a consequence, little is known about sustained attention performance of adults with ADHD. The aim of the present study was therefore to test the hypothesis of sustained attention deficits of adults with ADHD. Twenty-nine adults with ADHD and 30 healthy individuals were assessed on four 20-min tests of sustained attention, measuring alertness, selective attention, divided attention and flexibility. The deterioration of performance over time (time-on-task effects) was compared between patients with ADHD and healthy individuals to conclude on sustained attention performance. Compared to healthy individuals, patients with ADHD showed significant deficits of medium size in selective attention and divided attention. Furthermore, medium sustained attention deficits was observed in measures of alertness, selective attention and divided attention. This study supports the notion of sustained attention deficits of adults with ADHD.

Driving and attention deficit hyperactivity disorder

Adults with attention deficit hyperactivity disorder (ADHD) suffer from various impairments of cognitive, emotional and social functioning, which can have considerable consequences for many areas of daily living. One of those areas is driving a vehicle. Driving is an important activity of everyday life and requires an efficient interplay between multiple cognitive, perceptual, and motor skills. In the present study, a selective review of the literature on driving-related difficulties associated with ADHD is performed, seeking to answer whether individuals with ADHD show increased levels of unsafe driving behaviours, which cognitive (dys)functions of individuals with ADHD are related to driving difficulty, and whether pharmacological treatment significantly improves the driving behaviour of individuals with ADHD. The available research provides convincing evidence that individuals with ADHD have different and more adverse driving outcomes than individuals without the condition. However, it appears that not all individuals with ADHD are affected uniformly. Despite various cognitive functions being related with driving difficulties, these functions do not appear helpful in detecting high risk drivers with ADHD, nor in predicting driving outcomes in individuals with ADHD, since impairments in these functions are defining criteria for the diagnoses of ADHD (e.g., inattention and impulsivity). Pharmacological treatment of ADHD, in particular stimulant drug treatment, appears to be beneficial to the driving difficulties experienced by individuals with ADHD. However, additional research is needed, in particular further studies that address the numerous methodological weaknesses of many of the previous studies.

Reprint of "Deficits of hot executive function in developmental coordination disorder: Sensitivity to positive social cues"

Recent research shows that children with motor coordination problems (or developmental coordination disorder--DCD) show deficits in not only cool executive function (EF), but also hot EF. We aimed to determine whether this deficit of hot EF is due to heightened sensitivity to rewarding stimuli, specifically, or to a general deficit of cognitive control, like inhibition. Using two versions of a go/no-go task, one with neutral facial expressions and the other with happy and fearful faces, we compared 12 children with DCD with 28 typically-developing children, aged 7-12 years. Like earlier studies, children responded faster to happy faces. Both groups showed comparable accuracy in response to go targets, and also had similar commission errors, except when the no-go stimulus was a happy face. Importantly, the DCD group made significantly more commission errors to happy faces failing to suppress their response on more than half of the no-go trials. These results suggest a heightened sensitivity to emotionally significant distractors in DCD; this type of impulsivity may undermine self-regulation in DCD, with possible implications for adaptive function and emotional well-being. We argue that the interaction of cognitive control and emotion processing networks may be disrupted in DCD or delayed in development.

Overview of Attention Deficit Hyperactivity Disorder in Young Children

Attention deficit hyperactivity disorder (ADHD) is a complex disorder, which can be seen as a disorder of life time, developing in preschool years and manifesting symptoms (full and/or partial) throughout the adulthood; therefore, it is not surprising that there are no simple solutions. The aim of this paper is to provide a short and concise review which can be used to inform affected children and adults; family members of affected children and adults, and other medical, paramedical, non-medical, and educational professionals about the disorder. This paper has also tried to look into the process of how ADHD develops; what are the associated problems; and how many other children and adults are affected by such problems all over the world basically to understand ADHD more precisely in order to develop a better medical and or non-medical multimodal intervention plan. If preschool teachers and clinicians are aware of what the research tells us about ADHD, the varying theories of its cause, and which areas need further research, the knowledge will assist them in supporting the families of children with ADHD. By including information in this review about the connection between biological behavior, it is hoped that preschool teachers and clinicians at all levels will feel more confident about explaining to parents of ADHD children, and older ADHD children themselves about the probable causes of ADHD.

Attention Deficit/Hyperactivity Disorder symptoms and cognitive abilities in the late-life cohort of the PATH through life study

Attention Deficit/Hyperactivity Disorder (ADHD) is a common neuropsychiatric disorder that has not been well studied in older adults. In this study we examined relationships between ADHD symptoms and cognitive ability and compared them between middle-age (MA; 48-52 years) and older-age (OA; 68-74 years) adults sampled from the same population. ADHD, mood disorder symptoms and cognitive abilities were assessed in a large population-based sample (n = 3443; 50% male). We measured current ADHD symptoms using the adult ADHD Self-Report Scale (ASRS), which we found to have the same underlying structure in both cohorts. Older adults reported significantly lower levels of ADHD symptoms and 2.2% of the OA cohort scored equal or above the ASRS cut-off score of 14 (which has been previously associated with ADHD diagnosis) compared with 6.2% of MA adults. Symptom levels were not significantly different between males and females. Using multi-group structural equation modelling we compared ADHD symptom-cognitive performance relationships between the two age groups. Generally higher ADHD symptoms were associated with poorer cognitive performance in the MA cohort. However, higher levels of inattention symptoms were associated with better verbal ability in both cohorts. Surprisingly, greater hyperactivity was associated with better task-switching abilities in older adults. In the OA cohort ADHD symptom-cognition relationships are indirect, mediated largely through the strong association between depression symptoms and cognition. Our results suggest that ADHD symptoms decrease with age and that their relationships with co-occurring mood disorders and cognitive performance also change. Although symptoms of depression are lower in older adults, they are much stronger predictors of cognitive performance and likely mediate the effect of ADHD symptoms on cognition in this age group. These results highlight the need for age-appropriate diagnosis and treatment of comorbid ADHD and mood disorders.

Complex prospective memory in adults with attention deficit hyperactivity disorder

Objectives

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

Methods

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

Results

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

Conclusions

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

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.

Methylphenidate induces lipid and protein damage in prefrontal cortex, but not in cerebellum, striatum and hippocampus of juvenile rats

The use of psychostimulant methylphenidate has increased in recent years for the treatment of attention-deficit hyperactivity disorder in children and adolescents. However, the behavioral and neurochemical changes promoted by its use are not yet fully understood, particularly when used for a prolonged period during stages of brain development. Thus, the aim of this study was to determine some parameters of oxidative stress in encephalic structures of juvenile rats subjected to chronic methylphenidate treatment. Wistar rats received intraperitoneal injections of methylphenidate (2.0 mg/kg) once a day, from the 15th to the 45th day of age or an equivalent volume of 0.9% saline solution (controls). Two hours after the last injection, animals were euthanized and the encephalic structures obtained for determination of oxidative stress parameters. Results showed that methylphenidate administration increased the activities of superoxide dismutase and catalase, but did not alter the levels of reactive species, thiobarbituric acid reactive substances levels and sulfhydryl group in cerebellum of rats. In striatum and hippocampus, the methylphenidate-treated rats presented a decrease in the levels of reactive species and thiobarbituric acid reactive substances, but did not present changes in the sulfhydryl groups levels. In prefrontal cortex, methylphenidate promoted an increase in reactive species formation, SOD/CAT ratio, and increased the lipid peroxidation and protein damage. These findings suggest that the encephalic structures respond differently to methylphenidate treatment, at least, when administered chronically to young rats. Notably, the prefrontal cortex of juvenile rats showed greater sensitivity to oxidative effects promoted by methylphenidate in relation to other encephalic structures analyzed.

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.

Pergolide treatment of cognitive deficits associated with schizotypal personality disorder: continued evidence of the importance of the dopamine system in the schizophrenia spectrum

Cognitive deficits observed in schizophrenia are also frequently found in individuals with other schizophrenia spectrum disorders, such as schizotypal personality disorder (SPD). Dopamine appears to be a particularly important modulator of cognitive processes such as those impaired in schizophrenia spectrum disorders. In a double-blind, placebo-controlled clinical trial, we administered pergolide, a dopamine agonist targeting D(1) and D(2) receptors, to 25 participants with SPD and assessed the effect of pergolide treatment, as compared with placebo, on neuropsychological performance. We found that the pergolide group showed improvements in visual-spatial working memory, executive functioning, and verbal learning and memory. These results suggest that dopamine agonists may provide benefit for the cognitive abnormalities of schizophrenia spectrum disorders.

Dose-related immunohistochemical and ultrastructural changes after oral methylphenidate administration in cerebrum and cerebellum of the rat

Methylphenidate is a piperidine derivative and is the drug most often used to treat attention deficit/hyperactivity disorder of children and young adults. Our aim is to investigate dose-dependent dopamine-2 receptor and glial fibrillary acidic protein expression and ultrastructural changes of the rat brain, to demonstrate possible toxicity of the long-term and high dose use of the methylphenidate. In this study, 27 female prepubertal Wistar albino rats, divided into three different dose groups (5, 10 and 20 mg/kg) were treated orally with methylphenidate dissolved in saline solution for 5 days per week during 3 months. At the end of the third month, tissues were removed and sections were collected for immunohistochemical and ultrastructural studies. We believe that methylphenidate causes dose-related activation of the dopaminergic system in several brain regions especially in ventral tegmental area and also causing neuronal degeneration and capillary wall structural changes such as basal membrane thickness and augmentation of the pinostatic vesicle in the endothelial cells. Also, increased dose of Ritalin is inducing astrocytes hypertrophy especially astrogliosis in pia-glial membrane and this is the result of the degenerative changes in prefrontal cortex region due to high dose methylphenidate administration. The dose-related accumulation of the astrocytes in capillary wall might well be a consequence of the need for nutrition of the neuronal tissue, due to transport mechanism deficiency related to neuronal and vascular degeneration. Thus, we believe that the therapeutic dose of methylphenidate must be kept in minimum level to prevent ultrastructural changes.

Methylphenidate treatment increases Na(+), K (+)-ATPase activity in the cerebrum of young and adult rats

Methylphenidate is a central nervous system stimulant used for the treatment of attention-deficit hyperactivity disorder. Na(+), K(+)-ATPase is a membrane-bound enzyme necessary to maintain neuronal excitability. Considering that methylphenidate effects on central nervous system metabolism are poorly known and that Na(+), K(+)-ATPase is essential to normal brain function, the purpose of this study was to evaluate the effect of this drug on Na(+), K(+)-ATPase activity in the cerebrum of young and adult rats. For acute administration, a single injection of methylphenidate (1.0, 2.0, or 10.0 mg/Kg) or saline was given to rats on postnatal day 25 or postnatal day 60, in the young and adult groups, respectively. For chronic administration, methylphenidate (1.0, 2.0, or 10.0 mg/Kg) or saline injections were given to young rats starting at postnatal day 25 once daily for 28 days. In adult rats, the same regimen was performed starting at postnatal day 60. Our results showed that acute methylphenidate administration increased Na(+), K(+)-ATPase activity in hippocampus, prefrontal cortex, and striatum of young and adult rats. In young rats, chronic administration of methylphenidate also enhanced Na(+), K(+)-ATPase activity in hippocampus and prefrontal cortex, but not in striatum. When tested in adult rats, Na(+), K(+)-ATPase activity was increased in all cerebral structures studied. The present findings suggest that increased Na(+), K(+)-ATPase activity may be associated with neuronal excitability caused by methylphenidate.

Abnormal affective responsiveness in attention-deficit/hyperactivity disorder: subtype differences

BACKGROUND

Emotional-motivational dysfunctions likely contribute to attention-deficit/hyperactivity disorder (ADHD), especially to hyperactive and impulsive symptoms. This study examined the affective modulation of the startle reflex in a large sample of ADHD patients. The aim was to compare subtypes of ADHD.

METHODS

One hundred ninety-seven unmedicated adult ADHD patients (127 combined type [ADHD-C]; 50 inattentive type [ADHD-I]; 20 hyperactive-impulsive type [ADHD-HI]) and 128 healthy control subjects were examined. The affect-modulated startle response as well as valence and arousal ratings were assessed for pleasant, neutral, and unpleasant picture stimuli.

RESULTS

Control subjects exhibited startle response attenuation and potentiation by pleasant and unpleasant pictures, respectively. In ADHD-HI, startle response was not attenuated by pleasant and not potentiated by unpleasant stimuli. In ADHD-C, startle response was not attenuated by pleasant pictures, and ADHD-I responded similar to control subjects but startle response was attenuated to a lesser degree by pleasant stimuli. The ADHD-HI group rated all pictures as more positive, and male ADHD-HI rated unpleasant stimuli as less arousing.

CONCLUSIONS

This is the first study to assess the affect-modulated startle response in ADHD. It confirms emotional dysfunctions in these patients; all subtypes showed more or less diminished emotional reactions to pleasant stimuli. The hyperactive-impulsive type was also marked by blunted reactions to unpleasant stimuli. Results suggest that response patterns to emotional cues or reward may help to differentiate ADHD subtypes. Blunted emotional reactivity is especially pronounced in ADHD patients with symptoms of hyperactivity and impulsivity (ADHD-C, ADHD-HI).

Characteristics of adults with attention-deficit/hyperactivity disorder and past conduct disorder

OBJECTIVE

DSM-IV Attention-deficit/hyperactivity disorder (ADHD) comorbid with DSM-IV conduct disorder (CD) in childhood/adolescence has been proposed as a 'distinct subtype'. The present study investigated subsequent psychopathological characteristics of this proposed subtype in adults.

METHOD

Questionnaires were completed by 71 adults (mean age 29.6 years) with ADHD and their informants.

RESULTS

The 39 subjects with a history of past CD, when compared with the remaining subjects, were associated with significantly increased ratings of aspects of ADHD-related impulsivity, with features of all three DSM-IV 'Clusters' of personality disorders (PDs) (in particular of 'Cluster B' PDs) and with other psychopathology. Also, there were significant correlations between the number of endorsed past CD criteria and various self-ratings of psychopathology.

CONCLUSION

The results indicate the psychopathological characteristics of adults with a history of the proposed 'ADHD with CD' subtype. The findings are relevant to future studies of ADHD subtypes in adults.

Pharmacological and therapeutic directions in ADHD: Specificity in the PFC

BACKGROUND

Recent directions in the treatment of ADHD have involved both a broadening of pharmacological perspectives to include nor-adrenergic as well as dopaminergic agents. A review of animal and human studies of pharmacological and therapeutic directions in ADHD suggests that the D1 receptor is a specific site for dopaminergic regulation of the PFC, but optimal levels of dopamine (DA) are required for beneficial effects on working memory. Animal and human studies indicate that the alpha-2A receptor is also important for prefrontal regulation, leaving open the question of the relative importance of these receptor sites. The therapeutic effects of ADHD medications in the prefrontal cortex have focused attention on the development of working memory capacity in ADHD.

HYPOTHESIS

The actions of dopaminergic vs noradrenergic agents, currently available for the treatment of ADHD have overlapping, but different actions in the prefrontal cortex (PFC) and subcortical centers. While stimulants act on D1 receptors in the dorsolateral prefrontal cortex, they also have effects on D2 receptors in the corpus striatum and may also have serotonergic effects at orbitofrontal areas. At therapeutic levels, dopamine (DA) stimulation (through DAT transporter inhibition) decreases noise level acting on subcortical D2 receptors, while NE stimulation (through alpha-2A agonists) increases signal by acting preferentially in the PFC possibly on DAD1 receptors. On the other hand, alpha-2A noradrenergic transmission is more limited to the prefrontal cortex (PFC), and thus less likely to have motor or stereotypic side effects, while alpha-2B and alpha-2C agonists may have wider cortical effects. The data suggest a possible hierarchy of specificity in the current medications used in the treatment of ADHD, with guanfacine likely to be most specific for the treatment of prefrontal attentional and working memory deficits. Stimulants may have broader effects on both vigilance and motor impulsivity, depending on dose levels, while atomoxetine may have effects on attention, anxiety, social affect, and sedation via noradrenergic transmission.

TESTS OF THE HYPOTHESIS

At a theoretical level, the advent of possible specific alpha-2A noradrenergic therapies has posed the question of the role of working memory in ADHD. Head to head comparisons of stimulant and noradrenergic alpha-2A, alpha-2B and alpha-2C agonists, utilizing vigilance and affective measures should help to clarify pharmacological and therapeutic differences.

Neuropsychological assessment of attention in adults with different subtypes of attention-deficit/hyperactivity disorder

There is only little information about varying attention functions of adults with different DSM-IV subtypes of attention-deficit/hyperactivity disorder (ADHD). In the present study groups of adult patients with ADHD - predominantly inattentive type, ADHD - predominantly hyperactive-impulsive type or ADHD - combined type and three healthy control groups were compared regarding multiple components of attention. Assessment of attention was performed using a computerized neuropsychological test battery for attentional functions. In comparison with healthy subjects, the three patient groups displayed impairments of vigilance, selective attention, divided attention, and flexibility. These impairments of attention of ADHD subgroups were primarily observed with regard to reaction time. With regard to tonic and phasic alertness no differences between patient and control groups could be found. Comparison between ADHD subgroups revealed that DSM-IV subtypes of ADHD differ in measures of divided attention, selective attention and flexibility. Differences between ADHD subgroups were primarily observed with regard to task accuracy. The results suggest that while distinct profiles of attentional functioning were observed between adult patients with ADHD and healthy adults indicating gross disturbances of various attention functions in patients with ADHD, differences between ADHD subgroups were only weak.

Administration of oral methylphenidate during adolescence prevents suppressive development of dopamine projections into prefrontal cortex and amygdala after an early pharmacological challenge in gerbils

The enduring effects of postweaning subchronic methylphenidate (MP) treatment and/or previous early preweaning methamphetamine (MA) application on dopamine (DA) fiber density were investigated in multiple cortical and subcortical areas of the gerbil brain. The study aimed to explore three questions: (1) is the development of DA fiber innervation in control animals sensitive to a clinically relevant subchronic treatment with MP? (2) Is the development of DA fiber innervation in the forebrain altered by a single early MA challenge? (3) If so, might the subsequent institution of a therapeutically relevant MP application scheme interfere with such early induced alternative developmental trajectories for DA fiber innervation? For this purpose, gerbils pretreated both with saline and MA (50 mg/kg, i.p.) on day 14 received either H(2)O or MP (5 mg/kg) orally on days 30 to 60. On day 90, DA fibers were immunohistochemically detected and quantified. As a result, MP on its own did not have any significant influence on the postnatal development of the DA fiber systems, whereas it prevented a previously MA triggered suppressive development of DA fiber innervation in the prefrontal cortex and amygdala complex (30% less fiber innervation in both areas). Thus, MP prevented previously initiated miswiring of DA fibers from actually being implemented in the gerbil forebrain. During earlier studies, rather complex miswiring has been documented in response to an early preweaning MA challenge. This miswiring was associated with functional deficits resembling some of the symptoms of patients with ADHD. Therefore, morphogenetic properties of MP need further attention.

DNA damage in rats after treatment with methylphenidate

BACKGROUND

Methylphenidate (MPH) is a widely prescribed psychostimulant for the treatment of attention-deficit hyperactivity disorder (ADHD). Recently, some studies have addressed the genotoxic potential of the MPH, but the results have been contradictory. Hence, the present study aimed to investigate the index of cerebral and peripheral DNA damage in young and adult rats after acute and chronic MPH exposure.

METHODS

We used (1) single cell gel electrophoresis (Comet assay) to measure early DNA damage in hippocampus, striatum and total blood, and (2) micronucleus test in total blood samples.

RESULTS

Our results showed that MPH increased the peripheral index of early DNA damage in young and adult rats, which was more pronounced with chronic treatment and in the striatum compared to the hippocampus. Neither acute nor chronic MPH treatment increased micronucleus frequency in young or in adult rats. Peripheral DNA damage was positively correlated with striatal DNA damage.

CONCLUSION

These results suggest that MPH may induce central and peripheral early DNA damage, but this early damage may be repaired.

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.

Questionnaire ratings of attention-deficit/hyperactivity disorder (ADHD) in adults are associated with spatial working memory

OBJECTIVE

Data related to brain function may have the potential to improve the reliability and validity of assessments for the aetiologically and clinically heterogeneous syndrome of attention-deficit/hyperactivity disorder (ADHD). This study investigated associations between questionnaire assessments of behavioural features of adults with ADHD and an aspect of neurocognitive performance which has been reported to be impaired in adults with ADHD.

METHODS

Fifty-nine adult patients with a DSM-IV diagnosis of ADHD, and their informants, completed questionnaires related to aspects of severity of ADHD. Associations were examined between questionnaire ratings and performance on a computer-administered task of spatial working memory (SWM).

RESULTS

Correlations between ratings of ADHD and SWM indicated moderate but significant correlations for patients' ratings, but not for informants' ratings. Also, patients who reported a past history of 'self-harm' (N=33) had a significantly worse mean performance on both measures of SWM (p=0.004, 0.003).

CONCLUSIONS

The results indicate that aspects of impulsivity, i.e. self-ratings of 'emotive' behaviour (involving rapid response to stimuli and marked reactivity of mood) and of past 'self-harm', show relatively strong associations with SWM performance in adults selected on the basis of an ADHD diagnosis. A profile of neurocognitive performances may have a role in the assessment of ADHD.

Attentional versus motor inhibition in adults with attention-deficit/hyperactivity disorder

Faulty inhibition is theorized to be a central feature in attention-deficit/hyperactivity disorder (ADHD), but it remains unclear whether inhibitory impairments encompass both motoric and attentional domains. Further, characterization of inhibitory deficits in adults with ADHD is needed. We experimentally assessed adults who met diagnostic criteria for ADHD and a subgroup who had partially remitted. Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) subtype effects were also examined. Motoric inhibition was assessed with the antisaccade task, and attentional inhibition was assessed with the attentional blink (AB) task. Antisaccade results replicated prior findings of extended latencies and increased anticipatory saccades in ADHD. Errors, however, appeared to be epiphenomenal to ADHD as they were absent when symptoms had partially remitted. Anticipatory saccades appeared as potential core problems that remained even when symptoms had improved. Differential response patterns were found for predominantly inattentive and combined subtypes, with the latter showing increasing anticipatory movements with increasing fixation time. In the AB task, ADHD groups committed more errors but showed no convincing evidence of an abnormal blink. These results demonstrate clear effects on motoric inhibition but not attentional inhibition in adults with ADHD.

The Wuerzburg Research Initiative on Adult Attention-Deficit/Hyperactivity Disorder (WURIN-AADHD): multi-layered evaluation of long-term course

Although the neurobiological basis of the clinical entity of attention-deficit/hyperactivity disorder (ADHD) is evident, data from studies on pathomechanism-phenotype correlations are inconsistent. There are several obvious limitations of the DSM-IV diagnostic criteria to describe an adequate phenotype of adult ADHD. A dimensional model of neurobiologically based endophenotypes is therefore more likely to be compatible with the genetic model of quantitative trait loci. The primary goal of the Wuerzburg Research Initiative on Adult Attention-Deficit/Hyperactivity Disorder (WURIN-AADHD) is to test the validity of two endophenotypes, deficit in response inhibition and impairment of working memory, using various psychometric and neurobiological strategies of investigation in adult patients with ADHD. An additional objective is the investigation of the long-term course of adult ADHD. The conclusive description of valid endophenotypes of ADHD is an ongoing process that may result in a comprehensive neurobiological model for ADHD or its symptom dimensions integrating genetic, neural, cognitive, and behavioral mechanisms. This model will eventually facilitate description of complete causal connections occurring across the lifespan from early development to adulthood and is also likely to accelerate development of more specific and efficient therapeutic strategies in adult ADHD.

Methylphenidate-induced improvements of various measures of attention in adults with attention deficit hyperactivity disorder

The present study examined the effect of the stimulant medication methylphenidate (MPH) on attentional functioning of adults with ADHD. Sixteen adults with a diagnosed ADHD without comorbidity were assessed twice, at baseline off MPH and following MPH treatment. The assessment battery consisted of reaction time tasks of low complexity, including measures of alertness--subdivided into tonic and phasic alertness, vigilance, divided attention, flexibility and such aspects of selective attention as including focused attention, inhibition and integration of sensory information. In addition, 16 healthy participants who were matched to adults with ADHD according to sex, age, education level and intellectual functions were also assessed twice using the same test battery. The results of the present study suggest that adults with ADHD off stimulant medication are seriously impaired in various components of attention including vigilance, divided attention, selective attention and flexibility. These impairments of attention were observed primarily in regard to reaction time and its variability. Treatment of adults with ADHD using individually tailored doses of MPH has a positive effect on measures of alertness, vigilance, selective attention, divided attention and flexibility. However, even on MPH adults with ADHD displayed considerable deficits in vigilance and integration of sensory information. The present findings indicate that adults with ADHD are not differentially impaired in attentional processes but may suffer from a more global deficit of attention. Although MPH treatment has been found to be effective in the treatment of the attention deficit of adults with ADHD, additional treatment appears to be necessary.

A review of the use of modafinil for attention-deficit hyperactivity disorder

Modafinil (Provigil) is a novel wakefulness-promoting agent that has been shown to have greater efficacy than placebo in the treatment of attention-deficit hyperactivity disorder (ADHD) in children and adults. In particular, three large, drug-company sponsored trials of a film-coated formulation of modafinil (modafinil-ADHD; Sparlon) in children and adolescents with ADHD demonstrated consistent improvements in ADHD symptoms compared with placebo. Mean reductions in symptom ratings (measured using the ADHD-Rating Scale-IV school version questionnaire) ranged from 15.0 to 19.7 (7.3 to 10.1 for placebo). The most common adverse events were insomnia, headache and decreased appetite. Modafinil was generally well tolerated with most side effects considered mild to moderate in severity. Modafinil may have advantages over current therapies for ADHD in that it can be administered once daily and has fewer reinforcing properties than traditional stimulants. Modafinil could potentially be a valuable new treatment option for patients with ADHD. However, rigorous comparative studies with current first-line treatments for ADHD and longer-term independent studies are necessary before modafinil's role in the treatment of ADHD can be fully established.

Executive functions and ADHD in adults: evidence for selective effects on ADHD symptom domains

Dual-process models of attention-deficit/hyperactivity disorder (ADHD) suggest that both executive functioning and regulatory functions (e.g., processing speed) are involved and that executive function weaknesses may be associated specifically with symptoms of inattention-disorganization but not hyperactivity-impulsivity. Adults aged 18-37 (105 with ADHD, 90 controls) completed a neuropsychological battery. The ADHD group had weaker performance than did the control group (p<.01) on both executive and speed measures. Symptoms of inattention-disorganization were uniquely related to executive functioning with hyperactivity-impulsivity controlled. Inattention was associated with slower response speed, and hyperactivity-impulsivity with faster output speed. Results were not accounted for by IQ, age, gender, education level, or comorbid disorders. Findings are discussed in terms of developmental and dual-process models of ADHD leading into adulthood.

Attention deficit hyperactivity disorder: a review of the essential facts

Abstract Attention deficit hyperactivity disorder (ADHD) is a complex disorder, where both genetic and environmental influences make a substantial contribution to the risk for the disorder. One of the challenges facing clinicians is to simplify for parents the multifaceted reasons why their child may have developed ADHD, explain the associated symptoms, and encourage parents to participate in intervention. Increasing parents understanding about ADHD should make them better informed about the disorder, more likely to consent to intervention, and increase adherence to both psychosocial and pharmacological treatment. The aim of this review is to provide clinicians with a brief synopsis of our current understanding about the aetiology of ADHD, co-morbidity and associated problems, developmental course and intervention options.

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.

Assessment of hot and cool executive function in young children: age-related changes and individual differences

Although executive function (EF) is often considered a domain-general cognitive function, a distinction has been made between the "cool" cognitive aspects of EF more associated with dorsolateral regions of prefrontal cortex and the "hot" affective aspects more associated with ventral and medial regions (Zelazo and Mller, 2002). Assessments of EF in children have focused almost exclusively on cool EF. In this study, EF was assessed in 3- to 5-year-old children using 2 putative measures of cool EF (Self-Ordered Pointing and Dimensional Change Card Sort) and 2 putative measures of hot EF (Children's Gambling Task and Delay of Gratification). Findings confirmed that performance on both types of task develops during the preschool period. However, the measures of hot and cool EF showed different patterns of relations with each other and with measures of general intellectual function and temperament. These differences provide preliminary evidence that hot and cool EF are indeed distinct, and they encourage further research on the development of hot EF.

Impulsivity among adolescents with ADHD and bronchial asthma

OBJECTIVE

To determine the level of impulsivity of adolescents diagnosed as suffering from ADHD, Bronchial Asthma and Healthy adolescents (without any chronic disease).

METHODS

All participants (n=97) had completed the Barrett (Bis 10) questionnaire.

RESULTS

The adolescents suffering from Attention-deficit hyperactivity disorder (ADHD) scored the highest points 51.6; the control group without any chronic disease was second with 25.2 and the asthmatic adolescents were third with 23.4 points for their impulsivity.

CONCLUSION

It should be made clear to the people that the child comes in contact with his impulsive behavior is uncontrollable, and there is no justification for being angry with him nor any punishment. Patience and education is the answer. These adolescent should be under professional care in order to help him define more acceptable ways and means of deportment according to the norms and standards of his society.

Attention deficit hyperactivity disorder and borderline personality disorder

To evaluate the association between attention deficit hyperactivity disorder (ADHD) and the diagnosis of borderline personality disorder (BPD) in adulthood, a systematic review of published follow-up data, mainly from observational studies was done. Electronic databases Medline, PsychInfo and PSYNDEXplus were searched from their earliest entries. All studies suggested significant relationships between ADHD and BPD. From a phenomenological point of view there seem to exist some similarities between these two disorders: deficits in affect regulation and impulse control, substance abuse, low self esteem and disturbed interpersonal relationship are common in both conditions. From a neuropsychological point of view dissociation in BPD might be regarded as a special form of behavioral inhibition and sustained attention comparable to ADHD. Possible therapeutic strategies of comorbid ADHD and BPD are discussed.

Executive and motivational processes in adolescents with Attention-Deficit-Hyperactivity Disorder (ADHD)

BACKGROUND

The objective of the current study was to examine performance and correlates of performance on a decision-making card task involving risky choices (Iowa Gambling Task) in adolescents with ADHD and comparison controls. Forty-four participants with ADHD and 34 controls were administered measures of estimated intellectual ability, working memory, and the card task. Also, behavioural ratings were obtained from parents and teachers.

RESULTS

Adolescents with ADHD scored lower on the measures of intellectual ability, working memory, and made less advantageous selections on the card task compared to controls. Performance on measures of intellectual ability and working memory were unrelated to card task performance in both the ADHD and control samples. Parent ratings of hyperactivity/impulsivity were significantly associated with card task performance in the adolescents with ADHD, but not in controls.

CONCLUSION

These findings demonstrate impaired decision-making in adolescents with ADHD, and the separability of motivational and executive function processes, supporting current dual pathway models of ADHD.

Stimulants and the developing brain

For almost 70 years, children have received stimulants for the treatment of attention deficit hyperactivity disorder [ADHD (initially called hyperkinetic syndrome)], with little understanding of the long-term effects of these drugs on brain development. The maturation and refinement of the brain during childhood and adolescence, including the overproduction and selective elimination of synapses, is based on genetic programming and experience. The effects of stimulant drugs during different stages of this process have unique short-term, acute effects that also influence their long-term effects. Chronic, pre-pubertal exposure alters the expected developmental trajectory of brain structure and function and results in a different topography in adulthood. The timing of exposure (childhood versus adolescence), the age of examination after drug exposure (immediately or delayed into adulthood) and sex influence the observable effects. Preclinical studies of the effects of stimulant exposure provide increased understanding about the impact of stimulant drugs on brain development and provide insight into new treatment options for ADHD and other disorders of childhood.

Imaging the effects of methylphenidate on brain dopamine: new model on its therapeutic actions for attention-deficit/hyperactivity disorder

Methylphenidate hydrochloride (MP) is an effective treatment for attention-deficit/hyperactivity disorder (ADHD), a common neurobehavioral disorder of childhood onset characterized by inattention, hyperactivity, and distractibility. Methylphenidate hydrochloride blocks the dopamine transporters (DAT), the main mechanism for removing dopamine (DA) from the synapse, is believed to be involved in its therapeutic properties. However, the mechanism(s) by which increases in DA improve symptomatology in ADHD are not completely understood. Our studies of the dopaminergic effects of MP in the human brain using positron emission tomography (PET) have shown that MP blocks DAT, and that extracellular DA increases in proportion to the level of blockade and the rate of DA release (modulated by DA cell firing). These DA increases are greater when MP is given concomitantly with a salient stimulus than with a neutral stimulus, documenting the context dependency of MP effects. Additionally, MP-induced increases in DA are associated with an enhanced perception of the stimulus as salient. We postulate the MP's therapeutic effects are due in part to its ability to enhance the magnitude of DA increases induced by stimuli that by themselves generate weak responses, enhancing their saliency and the attention and interest they elicit. We postulate that these effects would improve school performance.

Neurocognitive effects of methylphenidate in adult attention-deficit/hyperactivity disorder

RATIONALE

Features of childhood attention-deficit/hyperactivity disorder (ADHD) often persist into adulthood. It has been shown that adult ADHD is associated with various neurocognitive deficits, including impairments in spatial working memory (SWM) and attention. It is not known whether these deficits are ameliorated by methylphenidate in adult ADHD.

OBJECTIVES

The aim of this study was to evaluate the neurocognitive effects of a single dose of methylphenidate on SWM, visual memory, spatial span and sustained attention in adult ADHD.

METHODS

Twenty-four adult patients, recruited from a specialised clinic for the assessment of adult ADHD, were entered into a double-blind, randomised, placebo-controlled crossover study using a single 30 mg dose of methylphenidate.

RESULTS

Eighteen patients met DSM-IV criteria for adult ADHD. Methylphenidate resulted in an improvement in SWM performance and sustained attention, together with a speeding in response time, in these patients. Six patients with attentional difficulties, who did not meet a DSM-IV diagnosis of ADHD, showed a different pattern of response to methylphenidate compared to the ADHD group. For the combined group, moderate correlations were shown between childhood ratings of ADHD (both self-reported and informant ratings) and response to methylphenidate on the SWM task.

CONCLUSIONS

Adults with ADHD had a similar neurocognitive response to methylphenidate to that previously reported for childhood ADHD. Our results provide further support for the validity of the ADHD syndrome as defined by DSM-IV and indicate possible neurocognitive substrates for clinical improvement with chronic methylphenidate.

A Review of Rating Scales for Measuring Behavior Change Due to Frontal Systems Damage

OBJECTIVE

To perform a critical review of scales designed to measure frontal behavior change.

BACKGROUND

Changes in cognition due to frontal disease or damage have been well described, but noncognitive changes in behavior are often more deleterious functionally for frontal patients.

METHOD

The review concentrates on five behavior rating scales: the Behavior Rating Inventory of Executive Functions (BRIEF), the Dysexecutive Questionnaire (DEX), the Frontal Behavior Inventory (FBI), the Frontal Systems Behavior Scale (FrSBe), the Iowa Rating Scales of Personality Change (IRSPC), and the Neuropsychiatric Inventory (NPI). Other scales purporting to measure specific aspects of frontal functioning, but having less research support, are described briefly.

RESULTS AND CONCLUSIONS

The BRIEF and FrSBe have good reliability and large-scale norms. No norms are available for the other scales. The FrSBe and IRSPC have been shown to be valid in discriminating frontal from nonfrontal lesioned patients, but this has not been shown in the other scales. The FBI and NPI require trained raters, whereas the FrSBe, IRSPC, and BRIEF are administered to patients and/or family informants directly. The NPI and FBI are sensitive to certain changes in behavior attributed to frontal systems disruption but have been used primarily in dementia.

Altering the course of neurodevelopment: a framework for understanding the enduring effects of psychotropic drugs

Childhood is a time filled with wondrous changes, as brain plasticity permits experiences to shape the immature brain to meet the demands of the environment. Change occurs at various levels--from neuroanatomy, including within a given region and its connectivity to other regions, to the function of neurotransmitter systems and their reactivity to pharmacological agents in the short- and long-term. The nature and degree to which drug exposure influences the final adult topography is influenced greatly by the maturational phase of these critical factors. Moreover, evidence is slowly emerging that suggests that the long-term effects of drug exposure are delayed and expressed once the vulnerable system reaches maturation (i.e., typically during adulthood). This phenomenon is known as neuronal imprinting and occurs when the effects of drug exposure outlast the drug itself. Thus, understanding the persistent effects critically depends on the window of observation. Embracing this concept should influence how we conduct preclinical assessments of developmental drug exposure, and ultimately how we conduct clinical assessments of drug efficacy, effectiveness, and safety for the treatment of childhood psychiatric disorders. In this article, we present a model to provide a heuristic framework for making predictions about imprinted effects of childhood drug exposure. We then review epidemiological data on attention deficit hyperactivity disorder (ADHD) and childhood depression, prescription practices, and what is known regarding the long-term consequences of drug exposure in these populations. We conclude with a discussion of the current status of preclinical studies on juvenile stimulant exposure.

The specificity of clinical characteristics in adults with attention-deficit/hyperactivity disorder: a comparison with patients with borderline personality disorder

Characteristics of DSM-IV attention-deficit/hyperactivity disorder (ADHD) in adults can also be found as part of other psychiatric disorders. This study investigated the specificity of adult ADHD features in relation to patients with borderline personality disorder (BPD), a syndrome which shares some of its intrinsic features with ADHD and often co-occurs with ADHD. A group of 20 adult patients selected on the basis of a diagnosis of ADHD and 20 patients selected on the basis of a diagnosis of BPD were assessed by the self-report Attention Deficit Scales for Adults (ADSA). The two groups were matched for age, verbal IQ and gender. Of the nine ADSA scales, seven showed significant inter-group differences, in particular involving attention, organisation and persistence. The 'Consistency/Long-Term' scale, which mainly reflects impaired task and goal persistence, was the best discriminator between the groups. Furthermore, ratings on this scale correlated significantly with the error score of a computer-administered task of spatial working memory, the performance of which has been reported to be impaired in patients with ADHD. The results provide further validation for the ADSA scales and support a previous claim that 'long-term consistencies', i.e., related to task and goal persistence, is 'the centrepiece behavioural issue' for adults with ADHD.