A review of adult ADHD: a neuropsychological and neuroimaging perspective

Psychiatric comorbidities associated with a positive screening using the Montreal Cognitive Assessment (MoCA) test in subjects with severe alcohol use disorder

BACKGROUND

Patients with severe alcohol use disorder (SAUD) frequently show cognitive deficits that can be efficiently identified using screening tools such as the Montreal Cognitive Assessment (MoCA) test. These cognitive deficits, which reduce the efficacy of therapeutic interventions and may contribute to dropout and relapse, could be, however, partly due to a treatable other cause. Accordingly, this exploratory study examined whether psychiatric comorbid disorders can induce a positive MoCA screening among recently detoxified SAUD subjects.

METHODS

One hundred recently detoxified patients with SAUD were divided into two groups according to whether they presented cognitive deficits using the MoCA. Groups were compared for demographic data, SAUD severity, impulsivity, and psychiatric comorbidities. The significant parameters were then introduced in a logistic regression model to establish their relative contributions in a positive MoCA status in SAUD subjects.

RESULTS

Among the significant parameters revealed by the bivariable analyses, agoraphobia and current depressive episode were found to be significant predictors of the MoCA status in the multivariable comparisons.

CONCLUSIONS

A positive MoCA screening for cognitive impairments among post-detoxification SAUD patients could also be related to comorbid agoraphobia and depressive episode rather than to SAUD itself. A comprehensive psychiatric assessment must be performed in SAUD patients so that other potential causes of cognitive deficits, in particular with regard to mood and anxiety disorders, can be identified and treated.

Perception of emotional prosody in adults with attention deficit hyperactivity disorder

OBJECTIVE

Attention deficit hyperactivity disorder (ADHD) is associated with social conflicts. The purpose of this study was to explore domains of social cognition in adult patients with ADHD.

METHODS

The assessment of social cognition was based on established neuropsychological tests: the Tübinger Affect Battery (TAB) for prosody and the Cambridge Behaviour Scale (CBS) for empathy. The performance of adults with ADHD (N = 28) was compared with the performance of a control group (N = 29) matched according to basic demographic variables.

RESULTS

Treatment-naïve adults with ADHD showed deficits in emotional prosody (P = 0.02) and in the ability to empathize (P < 0.02) independent of executive functioning. In particular, their ability to perceive angry feelings was found to be compromised (P = 0.04). When emotional prosody was considered in relation to facial expressions, patients and controls showed no impairments (P > 0.2). No gender differences concerning social cognitive skills were detected.

CONCLUSIONS

ADHD is associated with social cognition impairments involving both emotional prosody and empathy.

Applicability of the Stop-Signal Task for Preschoolers With ADHD

Inhibitory deficits of children with attention deficit/hyperactivity disorder (ADHD) are well documented. However, the specific inhibition ability (stopping an ongoing response) of preschoolers with ADHD is little reported. This study adopted the tracking stop-signal task to examine preschoolers with ADHD. Twenty-eight children with ADHD (M = 6.1 year, SD = 0.6) were compared to 31 comparison children (M = 6.0 year, SD = 0.6) on a measure of inhibitory control. The results showed that preschool children with ADHD performed worse than their control groups on the stop-signal task, using the omission error index, implying an attention deficit. However, preschool children with ADHD did not exhibit significantly slower stop-signal reaction times relative to the control group. The ability of controlled response inhibition of preschool children may not be mature.

Anticipatory Electrodermal Response as a Differentiating Somatic Marker Between Children with ADHD and Controls

Six children with Attention Deficit Hyperactivity Disorder (ADHD) and five control children between the ages of 9 and 11 years were administered an adapted version of the Iowa Gambling Task while measuring anticipatory electrodermal response (EDR). Anticipatory EDR measures were compared between groups. Results indicate that the ADHD group exhibited significantly lower autonomic reactivity to anticipated consequences, evidencing a neuropsychological profile similar to patients with lesions in the ventromedial prefrontal cortex.

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.

OROS-methylphenidate efficacy on specific executive functioning deficits in adults with ADHD: a randomized, placebo-controlled cross-over study

Attention-deficit/hyperactivity disorder (ADHD) is linked to impaired executive functioning (EF). This is the first study to objectively investigate the effects of a long-acting methylphenidate on neurocognitive test performance of adults with ADHD. Twenty-two adults with ADHD participated in a 6-weeks study examining the effect of osmotic-release oral system methylphenidate (OROS-mph) on continuous performance tests (CPTs; objective measures), and on the self-reported ADHD rating scale (subjective measure) using a randomized, double-blind, placebo-controlled cross-over design. OROS-mph significantly improved reaction time variability (RTV), commission errors (CE) and d-prime (DP) as compared to baseline (Cohen's d>.50), but did not affect hit reaction time (HRT) or omission errors (OE). Compared to placebo, OROS-mph only significantly influenced RTV on one of two CPTs (p<.050). Linear regression analyses showed predictive ability of more beneficial OROS-mph effects in ADHD patients with higher EF severity (RTV: β=.670, t=2.097, p=.042; omission errors (OE): β=-.098, t=-4.759, p<.001), and with more severe ADHD symptoms (RTV: F=6.363, p=.019; HRT: F=3.914, p=.061). Side effects rates were substantially but non-significantly greater for OROS-mph compared to placebo (77% vs. 46%, p=.063). OROS-mph effects indicated RTV as the most sensitive parameter for measuring both neuropsychological and behavioral deficits in adults with ADHD. These findings suggest RTV as an endophenotypic parameter for ADHD symptomatology, and propose CPTs as an objective method for monitoring methylphenidate titration.

No clear effects of acute tryptophan depletion on processing affective prosody in male adults with ADHD

OBJECTIVE

Adults with attention deficit hyperactivity disorder (ADHD) have difficulties processing affective prosody, and research evidence demonstrates the importance of brain serotonin (5-HT) in the neurobiology of ADHD. This study aimed to investigate whether diminished brain 5-HT synthesis, as achieved by acute tryptophan depletion (ATD), can impair the processing of affective prosody in adults with ADHD.

METHOD

Twenty male patients with ADHD and twenty male healthy controls received ATD and a tryptophan-balanced control condition on separate days in a double-blind within-subject repeated measures crossover design. In both conditions, the Tübingen Affect Battery was administered in which subjects had to name the affective prosody of sentences with neutral, congruent, or incongruent semantic content.

RESULTS

Participants in the group of patients with ADHD perceived affective prosody less accurately than controls. Participants with ADHD showed compromised processing of sentences, committing more errors than healthy controls when identifying affect in instances of incongruent semantic content (P = 0.031). ATD did not contribute to this effect (all P > 0.5).

CONCLUSION

The difficulties male adults with ADHD have in accurately processing affective prosody may result from impairments in their ability to inhibit unwanted stimuli and impulses. No clear evidence implicates 5-HT as a cause of these impairments.

Swimming exercise alleviates the symptoms of attention-deficit hyperactivity disorder in spontaneous hypertensive rats

Attention-deficit hyperactivity disorder (ADHD) is a neurobehavioral disorder characterized by inattention, hyperactivity and impulsivity. In the present study, we investigated the effects of swimming exercise on the symptoms of ADHD in correlation with the expression levels of dopamine and the dopamine D2 receptor. Adult male spontaneous hypertensive rats (SHRs) were used as animal models of ADHD and Wistar-Kyoto rats were used as controls. The activity, impulsivity and levels of non-aggressive and aggressive behaviors in rats were measured. The short-term memory in the animal models of ADHD was assessed using an open-field test. The social interaction test, elevated plus maze test and step-through avoidance test were additionally performed. The expression levels of tyrosine hydroxylase (TH), which catalyzes the rate‑limiting step of dopamine synthesis, and the dopamine D2 receptor in the prefrontal cortex, substantia nigra and striatum were evaluated. The expression levels of TH and the dopamine D2 receptor were detected using immunohistochemistry and western blotting, respectively. In ADHD rats, the activity, impulsivity and levels of non-aggressive and aggressive behaviors were higher than that in control rats. By contrast, short-term memory in ADHD rats deteriorated. Swimming exercise suppressed hyperactivity, impulsivity and non-aggressive and aggressive behaviors, and alleviated the short-term memory impairment observed in ADHD rats. The expression levels of TH and the dopamine D2 receptor were decreased and increased in ADHD rats, respectively, when compared with control rats. Swimming exercise enhanced the expression of TH and suppressed the expression of the dopamine D2 receptor in ADHD rats. In the present study, swimming exercise improved the symptoms of ADHD by upregulating the expression of dopamine and downregulating the expression of the dopamine D2 receptor.

Measuring adult Attention Deficit Hyperactivity Disorder using the Quantified Behavior Test Plus

Attention Deficit Hyperactivity Disorder (ADHD) occurs in approximately 5% of the adult population and includes cardinal symptoms of hyperactivity, inattention, and impulsivity that may be difficult to identify with clinical routine methods. Continuous performance tests are objective measures of inattention and impulsivity that, combined with objective measures of motor activity, facilitate identification of ADHD among adults. The aim of the present study was to examine the sensitivity, specificity, and a composite measure of ADHD using objective measures of the ADHD-cardinal symptoms in adult participants with ADHD and non-ADHD normative participants. Cardinal symptoms were measured in 55 participants having ADHD, 202 non-ADHD normative participants, as well as 84 ADHD normative participants using the Quantified Behavior Test Plus. This test measures inattention and impulsivity using a continuous performance test, and hyperactivity using a motion-tracking system. A predictive variable for the detection of ADHD called Prediction of ADHD yielded 86% sensitivity and 83% specificity. A composite measure of ADHD cardinal symptoms was developed using a Weighed Core Symptoms scale that indicated the total amount of ADHD symptoms on a numeric scale from 0 to 100. The total amount of ADHD symptoms was measured on a scale and predicted with the categorical variable in a majority of the cases in the present study. Further studies are needed in order to confirm the results with regard to additional clinical and normative samples. Careful consideration of potential sex and diagnostic subtype differences are noteworthy aspects for future examinations of the new instruments.

The effect of reduced dopamine D4 receptor expression in the 5-choice continuous performance task: Separating response inhibition from premature responding

Impairments in attention/vigilance and response disinhibition are commonly observed in several neuropsychiatric disorders. Validating animal models could help in developing therapeutics for cognitive deficits and improving functional outcomes in such disorders. The 5-choice continuous performance test (5C-CPT) in mice offers the opportunity to assess vigilance and two forms of impulsivity. Since reduced dopamine D4 receptor (DRD4) function is implicated in several disorders, DRD4 is a potential therapeutic target for cognition enhancement. We trained wildtype (WT), heterozygous (HT), and knockout (KO) mice of the murine Drd4 to perform the 5C-CPT under baseline and variable stimulus duration conditions. To dissect motor impulsivity (premature responding) from behavioral disinhibition (false alarms), we administered the 5-HT(2C) antagonist SB242084 during an extended inter-trial-interval session. We also examined the preattentive and exploratory profile of these mice in prepulse inhibition (PPI) and the Behavioral Pattern Monitor (BPM). Reduced Drd4 expression in HT mice, as confirmed by quantitative RT-PCR, resulted in response disinhibition and impaired 5C-CPT performance, while premature responding was unaffected. Conversely, SB242084 increased premature responding without affecting response inhibition or attentional measures. No genotypic differences were observed in PPI or BPM behavior. Thus, reduced Drd4 expression impairs attentional performance, but not other behaviors associated with neuropsychiatric disorders. Moreover, the use of signal and non-signal stimuli in the 5C-CPT enabled the differentiation of response disinhibition from motor impulsivity in a vigilance task.

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.

Sensitivity and specificity of long wave infrared imaging for attention-deficit/hyperactivity disorder

OBJECTIVE

This study was the first to investigate the efficacy of long wave infrared (LWIR) imaging as a diagnostic tool for ADHD.

METHOD

This study was conducted to assess the sensitivity and specificity of LWIR imaging as a method of diagnosis among 190 patients (ages 4.4-57 years) with various diagnoses, including ADHD, who came into our office for neuropsychological evaluation.

RESULTS

LWIR imaging demonstrated a moderate level of sensitivity (65.71%) in identifying patients with ADHD and a high level of specificity (94%) in discriminating those with ADHD from those with other diagnoses. The overall classification rate was 73.16%. This was indicative of a high level of discriminant validity in distinguishing between patients with and without ADHD. There was a moderate level of agreement between LWIR imaging and multiple other diagnostic tests for ADHD.

CONCLUSIONS

LWIR imaging demonstrated high sensitivity and specificity as a diagnostic tool for ADHD. These results provide evidence for the efficacy of a novel, quick, and effective way to investigate the physiological basis of one of the most prevalent childhood psychiatric disorders.

Neural hyporesponsiveness and hyperresponsiveness during immediate and delayed reward processing in adult attention-deficit/hyperactivity disorder

BACKGROUND

Dysfunctional reward processing, accompanied by a limited ability to tolerate reward delays, has been proposed as an important feature in attention-deficit/hyperactivity disorder (ADHD).

METHODS

Using functional magnetic resonance imaging (fMRI), brain activation in adult patients with ADHD (n=14) and healthy control subjects (n=12) was examined during a series of choices between two monetary reward options that varied by delay to delivery.

RESULTS

Compared with healthy control subjects, hyporesponsiveness of the ventral-striatal reward system was replicated in patients with ADHD and was evident for both immediate and delayed rewards. In contrast, delayed rewards evoked hyperactivation in dorsal caudate nucleus and amygdala of ADHD patients. In both structures, neural activity toward delayed rewards was significantly correlated with self-rated ADHD symptom severity.

CONCLUSIONS

The finding of ventral-striatal hyporesponsiveness during immediate and delayed reward processing in patients with ADHD further strengthens the concept of a diminished neural processing of rewards in ADHD. Hyperactivation during delayed reward processing, gradually increasing along the ventral-to-dorsal extension of the caudate nucleus, and especially the concomitant hyperactivation of the amygdala are in accordance with predictions of the delay aversion hypothesis.

Mixed amphetamine salts extended-release in the treatment of adult ADHD: a randomized, controlled trial

INTRODUCTION

Attention-deficit/hyperactivity disorder (ADHD) is a serious neurobehavioral disorder of childhood onset that often persists into adolescence and adulthood. Functional impairments, underachievement, and difficult interpersonal relationships illustrate the need for effective treatment of ADHD through adulthood.

METHOD

This prospective, multisite, randomized, double-blind, placebo-controlled, parallel-group, dose-escalation study was conducted to assess the efficacy, safety, and duration of action of mixed amphetamine salts extended-release (MAS XR) in adults with ADHD, combined type. Adults > or =18 years of age were given placebo or MAS XR 20, 40, or 60 mg/day for 4 weeks. The main outcome measures were the ADHD Rating Scale and Conners' Adult ADHD Rating Scale Short Version Self-Report (CAARS-S-S).

RESULTS

Two hundred fifty-five subjects were randomly assigned to treatment with MAS XR or placebo. MAS XR treatment was associated with statistically and clinically significant ADHD symptom reduction at endpoint; mean ADHD Rating Scale scores were 18.5 for the 20-mg group (P=.001), 18.4 for the 40-mg group (P<.001), and 18.5 for the 60-mg group (P<.001). Adults with severe symptoms (ADHD Rating Scale score >32 at baseline) had significantly greater symptom reduction with the highest MAS XR dose (60 mg/day), however, this dose-response relationship was determined by post-hoc analysis. The mean MAS XR effect size was 0.8. Statistically significant (P<.05) improvements in CAARS-S-S ADHD index scores occurred at 4- and 12-hours postdose for all MAS XR groups, indicating a 12-hour duration of effect. Symptoms improved within the first treatment week. Most adverse events reported were mild or moderate in intensity, and the most commonly reported adverse events were consistent with the known profile of stimulant medications. Vital signs and electrocardiograms showed no clinically significant cardiovascular changes.

CONCLUSION

These results suggest that MAS XR is safe and effective in adults with ADHD and controlled ADHD symptoms for up to 12 hours.

Painel brasileiro de especialistas sobre diagnóstico do transtorno de déficit de atenção/hiperatividade (TDAH) em adultos

Considerando-se as dificuldades atuais do diagnóstico do transtorno do déficit de atenção/hiperatividade em adultos, foram reunidos especialistas brasileiros que fazem pesquisas nesta área, de modo a produzir diretrizes de consenso para uso no país. Foi realizada uma revisão não-sistemática preliminar e concebido um texto inicial, que foi repetidamente avaliado e editado pelos autores, com acréscimos e correções ao longo de 6 meses, através de correio eletrônico e de uma reunião posterior, patrocinada pela Associação Brasileira do Déficit de Atenção. A versão preliminar foi apresentada publicamente durante o congresso anual da Associação Brasileira de Psiquiatria, com comentários e sugestões dos participantes, para a redação da versão final.

Probing the limits of delay intolerance: preliminary young adult data from the Delay Frustration Task (DeFT)

Delay intolerance/aversion is one amongst a number of candidate neuropsychological endophenotypes for ADHD. Pilot data suggest that, because of potential ceiling effects, simple choice measures of delay tolerance used for children are probably not appropriate for adolescents and adults. The Delay Frustration Task (DeFT) is a new measure of delay intolerance, designed to be used in a similar form with adolescents and adults as well as children. In it delay frustration is indexed as the number and duration of responses made on a response key during a series of unpredictable and unsignalled delay periods, which interrupt the completion of a simple computer-based tests. The aim of this study was to provide preliminary data on the applicability of the task in a sample of young adults. The DeFT was administered to 49 male and female undergraduate students selected from a normal population-base. Their mean age was 23.14 (S.D.=1.54). Three measures of delay frustration were recorded across time intervals during the response window; the number of responses, their duration and their combined product (total time button was pressed) was calculated for each second interval bin during the post-response delay period. The AARS and HADS were used as screening questionnaires for ADHD and anxiety behaviour, respectively. The results indicated that young adults with high-ADHD symptoms scores pressed the button more than those with low ADHD scores during the post-response delay condition. While both groups increased responding across time within intervals this was significantly more marked in the high-ADHD symptom group. These effects became more pronounced when anxiety was controlled. Young adults with high-ADHD symptoms appear to be more sensitive to the imposition of unscheduled and unsignalled delay during a simple maths test. DeFT may provide a useful index of delay tolerance in young adults with ADHD. Future research needs to examine DeFT performance in different age groups and in clinical and non-clinical populations.