Fractionating Executive Functions of Adults With ADHD

Cognitive and Neuroimaging Profiles of Older Adults With Attention Deficit/Hyperactivity Disorder Presenting to a Memory Clinic

OBJECTIVE

Some features of attention-deficit/hyperactivity disorder (ADHD) may resemble those of mild cognitive impairment (MCI) in older adults, contributing to diagnostic uncertainty in individuals seeking assessment in memory clinics. We systematically compared cognition and brain structure in ADHD and MCI to clarify the extent of overlap and identify potential features unique to each.

METHOD

Older adults from a Cognitive Neurology clinic (40 ADHD, 29 MCI, 37 controls) underwent neuropsychological assessment. A subsample (n = 80) underwent structural neuroimaging.

RESULTS

Memory was impaired in both patient groups, but reflected a storage deficit in MCI (supported by relatively smaller hippocampi) and an encoding deficit in ADHD (supported by frontal lobe thinning). Both groups displayed normal executive functioning. Semantic retrieval was uniquely impaired in MCI.

CONCLUSION

Although ADHD has been proposed as a dementia risk factor or prodrome, we propose it is rather a pathophysiologically-unique phenotypic mimic acting via overlap in memory and executive performance.

Do group-based mindfulness meditation programs enhance executive functioning? A systematic review and meta-analysis of the evidence

Research examining the effects of group-based mindfulness interventions on executive functioning have yielded inconsistent findings, with some reports of enhanced performance and other reports of null findings. Inconsistencies in the literature may be due to methodological differences across studies, including the type of control group employed and sample characteristics (e.g., clinical vs. non-clinical samples). The current systematic review and meta-analysis examined the effect of group-based mindfulness programs on executive functioning in persons 18+ years of age. Following the standards for systematic review, a total of 29 studies were included in the meta-analysis, of which 21 comparisons contributed to the analysis of inhibition; nine to working memory; nine to attention shifting; and four to the analysis of verbal fluency. After removing outliers, random effects models suggested a small but significant synthesized effect of group-mindfulness training on overall executive functioning (95% CI = 0.256, 0.725). Examination of executive subdomains after removing outliers suggested a small, statistically significant effect for inhibition (95% CI = 0.055, 0.387), working memory (95% CI = 0.010, 0.437), and verbal fluency (95% CI = 0.071, 1.931). No significant pooled effects were found for attention shifting. A priori subgroup analysis by randomization, type of control group, and sample cohort revealed inconsistent results. Overall, the current review suggests that the effect of group-based mindfulness training on executive functioning is not robust.

Cognitive Control, Cognitive Biases and Emotion Regulation in Depression: A New Proposal for an Integrative Interplay Model

Research traditions on cognition and depression focus on relatively unconnected aspects of cognitive functioning. On one hand, the neuropsychological perspective has concentrated on cognitive control difficulties as a prominent feature of this condition. On the other hand, the clinical psychology perspective has focused on cognitive biases and repetitive negative patterns of thinking (i.e., rumination) for emotional information. A review of the literature from both fields reveals that difficulties are more evident for mood-congruent materials, suggesting that cognitive control difficulties interact with cognitive biases to hinder cognitive switching, working memory updating, and inhibition of irrelevant information. Connecting research from these two traditions, we propose a novel integrative cognitive model of depression in which the interplay between mood-congruent cognitive control difficulties, cognitive biases, and rumination may ultimately lead to ineffective emotion-regulation strategies to downregulate negative mood and upregulate positive mood.

Cognitive characterization of adult attention deficit hyperactivity disorder by domains: a systematic review

Attention deficit hyperactivity disorder (ADHD) is reportedly the most frequent neurodevelopmental disorder diagnosed during childhood, and it is recognized as a common condition in adulthood. We review the evidence to help identify cognitive domains associated to deficits in adult ADHD. A systematic review with narrative synthesis was performed, assessing studies on adult ADHD, neuropsychology and research on involved cognitive domains in adults 18+ years old with an established diagnosis of ADHD, in seven electronic databases (PubMed, PsychInfo, WebOfScience, Embase, Scopus, OvidSPMedline, and Teseo), and Worldcat and OpenGrey grey literature databases. 93 studies were included for this review, encompassing findings from a total 5574 adults diagnosed only with ADHD, medication-naïve or non-medicated at the moment of the assessment and 4880 healthy controls. Adults diagnosed with ADHD may show, when compared to healthy controls, a cognitive profile characterized by deficits across all attention modalities, processing speed, executive function (mainly working memory and inhibition with emphasis on reward delay and interference control), verbal memory, reading skills, social cognition and arithmetic abilities. A cognitive characterization of adult ADHD by domains is established beyond the sole consideration of attention and executive function problems. Along with these, verbal memory, language (mainly reading), social cognition and arithmetic abilities may also contribute to a more comprehensive characterization of the cognitive profile in adult ADHD.

Patients with mutations of the Thyroid hormone beta-receptor show an ADHD-like phenotype for performance monitoring: an electrophysiological study

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Mutations in the thyroid hormone receptor beta (THRB) lead to relative hyperthyroidism in the brain.

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Electrophysiological biomarkers of performance monitoring (ERN and Pe components) show a pattern similar to ADHD in carriers of THRB mutations.

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The phenotype of THRB mutation carriers is indistinguishable from ADHD with regard to performance monitoring.

Resistance to thyroid hormone beta (RTHβ) is a syndrome of reduced responsiveness of peripheral tissue to thyroid hormone, caused by mutations in the thyroid hormone receptor beta (THRB). Its cognitive phenotype has been reported to be similar to attention deficit hyperactivity disorder (ADHD). This study used electrophysiological biomarkers of performance monitoring in RTHβ to contribute further evidence on its phenotypical similarity to ADHD. Twenty-one participants with RTHβ aged 18–67 years and 21 matched healthy controls performed a modified flanker task during EEG recording. The RTHβ and control groups were compared on behavioural measures and components of event related potentials (ERPs), i.e. the error related negativity (ERN), the error positivity (Pe) and P3 component. There were no significant group differences with regard to behaviour. RTHβ subjects displayed significantly reduced ERN and Pe amplitudes compared to the controls in the response-locked ERPs. In addition, we observed reduced P3 amplitudes in both congruent and incongruent trials, as well as prolonged P3 latencies in RTHβ subjects in the stimulus-locked ERPs. Our findings reveal alterations in error detection and performance monitoring of RTHβ patients, likely indicating reduced error awareness. The electrophysiological phenotype of RTHß subjects with regard to action monitoring is indistinguishable from ADHD.

Potential Social and Neurocognitive Benefits of Aerobic Exercise as Adjunct Treatment for Patients With ADHD

Objective: The aim of the article is to review the evidence that aerobic exercise may be a useful adjunct treatment for ADHD. Method: Studies on physical, cognitive, and psychosocial aspects of aerobic exercise that are relevant to ADHD are reviewed and evaluated. Results: Stimulant medication, the main pharmacotherapy for ADHD, and aerobic exercise both act on catecholamine pathways. Aerobic exercise has been shown to be beneficial in preclinical studies on spontaneous hypertensive rats, an animal model of ADHD, and in clinical trials of children with ADHD, as an adjunct treatment to medication. Social and neurocognitive function in children and adults seem to be positively affected by exercise as well. Nevertheless, no controlled clinical trials in adults with ADHD have been conducted. Conclusion: Aerobic exercise may be a useful non-medication adjunct therapy for ADHD. The clinical effectiveness of aerobic exercise for ADHD in children and adults warrants further clinical studies.

Methylphenidate effects on processing speed in a clinical sample of adults with ADHD and substance use disorder: a pilot study

BACKGROUND

Substance use disorders (SUDs) are common comorbidities of Attention Deficit Hyperactivity Disorder (ADHD). The most commonly prescribed medication for ADHD is methylphenidate. The clinical response to methylphenidate may be monitored against DSM-5 symptomatology, rating scales or interviews.

AIMS

To evaluate the use of perceptual and cognitive processing speed measures to monitor methylphenidate effects in adults with ADHD and SUD.

METHODS

A Quick Test of Cognitive Speed (AQT) monitored perceptual and cognitive processing speed in 28 adults with ADHD and SUD on treatment with methylphenidate before and after the morning dose.

RESULTS

Twenty-six patients responded on AQT after the morning dose of methylphenidate. One-way ANOVA indicated significant treatment effects for color, form, and color-form combination naming, but not for shift cost values. Before the morning dose of methylphenidate, 92% were identified by cutoff time criteria for longer-than-normal processing times. After the morning dose of methylphenidate, 65% obtained color and form measures in the normal range for age peers. Only 35% obtained color-form processing measures in the normal range. Inter-individual response variability before medication intake was considerably larger than previously reported in studies of adults with ADHD only.

CONCLUSION

Proportionally, fewer adults with ADHD and SUD exhibited normalization of processing speed than previously observed for adults with ADHD without SUD. A potential clinical implication of the present study is that the AQT test may be used as a tool for dose-adjustment of central stimulants in the treatment of adults with ADHD and SUD.

Math Error Types and Correlates in Adolescents with and without Attention Deficit Hyperactivity Disorder

Objective: The aim of this study was to examine the types of errors made by youth with and without a parent-reported diagnosis of attention deficit and hyperactivity disorder (ADHD) on a math fluency task and investigate the association between error types and youths’ performance on measures of processing speed and working memory.

Method: Participants included 30 adolescents with ADHD and 39 typically developing peers between 14 and 17 years old matched in age and IQ. All youth completed standardized measures of math calculation and fluency as well as two tests of working memory and processing speed. Math fluency error patterns were examined.

Results: Adolescents with ADHD showed less proficient math fluency despite having similar math calculation scores as their peers. Group differences were also observed in error types with youth with ADHD making more switch errors than their peers.

Conclusion: This research has important clinical applications for the assessment and intervention on math ability in students with ADHD.

High IQ May "Mask" the Diagnosis of ADHD by Compensating for Deficits in Executive Functions in Treatment-Naïve Adults With ADHD

OBJECTIVE

To evaluate and compare the performance of adults with ADHD with high and standard IQ in executive functions (EF) tasks.

METHOD

We investigated the neuropsychological performance of 51 adults with ADHD, compared with 33 healthy controls (HC) while performing a wide battery of neuropsychological tests that measure executive functioning. Adults with clinical diagnosis of ADHD were divided into two groups according to their IQ level (IQ ≥ 110-ADHD group with more elevated IQ, and IQ < 110-ADHD group with standard IQ).

RESULTS

The ADHD group with standard IQ presented a worse executive functioning compared with the HC group in the following measures: Stroop 2 ( p = .000) and 3 ( p = .000), Trail Making Test (TMT) B ( p = .005), Wisconsin Card-Sorting Test (WCST)-perseverative errors ( p = .022) and failures to maintain set ( p = .020), Continuous Performance Test (CPT)-omission errors ( p = .005) and commission errors ( p = .000), and Frontal Assessment Battery (FAB)-conceptualization ( p = .016). The ADHD group with more elevated IQ presented only impairments in the CPT-commission errors ( p = .019) when compared with the control group.

CONCLUSION

Adults with ADHD and more elevated IQ show less evidence of executive functioning deficits compared with those with ADHD and standard IQ, suggesting that a higher degree of intellectual efficiency may compensate deficits in executive functions, leading to problems in establishing a precise clinical diagnosis.

The Key Search Subtest of the Behavioural Assessment of the Dysexecutive Syndrome in Children (BADS-C) Instrument Reveals Impaired Planning Without External Constraints in Children With Neurofibromatosis Type 1

Studies of executive function and its relationship with brain T2-weighted hyperintensities in children with neurofibromatosis type 1 (NF1) have yielded inconsistent results. We examined 16 children with NF1 aged 8 to 15 years, of normal intelligence, and compared their findings to those of 16 siblings and 16 typically developing children using the Behavioural Assessment of the Dysexecutive Syndrome in Children (BADS-C). NF1 patients had an adequate overall score at BADS-C, but showed significantly lower performance than typical peers in the Key Search subtest. This is a task that must be solved without any given rules, in which subjects must devise a strategy and an efficient search pattern transferable to other similar real situations. The Key Search scores were not correlated with number and signal characteristics of T2-weighted hyperintensities. Planning without external indications is impaired in children with NF1 because they have to rely entirely on self-organization and monitoring; this study provides information for remediation programs designed to improve functioning in daily life.

How Saccade Intrusions Affect Subsequent Motor and Oculomotor Actions

In daily activities, there is a close spatial and temporal coupling between eye and hand movements that enables human beings to perform actions smoothly and accurately. If this coupling is disrupted by inadvertent saccade intrusions, subsequent motor actions suffer from delays, and lack of coordination. To examine how saccade intrusions affect subsequent voluntary actions, we used two tasks that require subjects to make motor/oculomotor actions in response to a visual cue. One was the memory guided saccade (MGS) task, and the other the hand reaction time (RT) task. The MGS task required subjects to initiate a voluntary saccade to a memorized target location, which is indicated shortly before by a briefly presented cue. The RT task required subjects to release a button on detection of a visual target, while foveating on a central fixation point. In normal subjects of various ages, inadvertent saccade intrusions delayed subsequent voluntary motor, and oculomotor actions. We also studied patients with Parkinson's disease (PD), who are impaired not only in initiating voluntary saccades but also in suppressing unwanted reflexive saccades. Saccade intrusions also delayed hand RT in PD patients. However, MGS was affected by the saccade intrusion differently. Saccade intrusion did not delay MGS latency in PD patients who could perform MGS with a relatively normal latency. In contrast, in PD patients who were unable to initiate MGS within the normal time range, we observed slightly decreased MGS latency after saccade intrusions. What explains this paradoxical phenomenon? It is known that motor actions slow down when switching between controlled and automatic behavior. We discuss how the effect of saccade intrusions on subsequent voluntary motor/oculomotor actions may reflect a similar switching cost between automatic and controlled behavior and a cost for switching between different motor effectors. In contrast, PD patients were unable to initiate internally guided MGS in the absence of visual target and could perform only automatic visually guided saccades, and did not have to switch between automatic and controlled behavior. This lack of switching may explain the shortening of MGS latency by the saccade intrusion in PD patients.

Mindfulness Meditation Improves Mood, Quality of Life, and Attention in Adults with Attention Deficit Hyperactivity Disorder

OBJECTIVE

Adults with attention deficit hyperactivity disorder (ADHD) display affective problems and impaired attention. Mood in ADHD can be improved by mindful awareness practices (MAP), but results are mixed regarding the enhancement of attentional performance. Here we evaluated MAP-induced changes in quality of life (QoL), mood, and attention in adult ADHD patients and controls using more measures of attention than prior studies.

METHODS

Twenty-one ADHD patients and 8 healthy controls underwent 8 weekly MAP sessions; 22 similar patients and 9 controls did not undergo the intervention. Mood and QoL were assessed using validated questionnaires, and attention was evaluated using the Attentional Network Test (ANT) and the Conners Continuous Performance Test (CPT II), before and after intervention.

RESULTS

MAP enhanced sustained attention (ANT) and detectability (CPT II) and improved mood and QoL of patients and controls.

CONCLUSION

MAP is a complementary intervention that improves affect and attention of adults with ADHD and controls.