Basic and complex cognitive functions in Adult ADHD

Diagnostic Utility of Conners Continuous Performance Test-3 for Attention Deficit/Hyperactivity Disorder: A Systematic Review

OBJECTIVE

To review the literature on the utility of the Conners CPT-3 in persons with ADHD.

METHODS

A systematic review was conducted. Six databases were searched using inclusion criteria: research studies, year 2000+, English, and ages 8+. Two raters independently screened 1,480 title/abstracts and subsequently reviewed 399 full texts. Data extraction and critical appraisal were conducted. Reflective thematic analysis through inductive coding identified qualitative themes.

RESULTS

Thirteen studies met inclusion criteria with five themes identified. Five studies found CPT-3 was a weak or poor predictor of ADHD diagnosis while two found it was an adequate predictor. Two studies found CPT-3 could differentiate clients with comorbid ADHD/anxiety from ADHD or ADHD from obsessive-compulsive disorder. One found CPT-3 could not differentiate ADHD from ASD or comorbid ADHD/ASD.

CONCLUSIONS

Results revealed CPT-3 as a standalone measure is a weak or poor predictor of ADHD. Multiple measures for evaluating persons with ADHD are recommended.

Processing Speed Deficit and Its Relationship with Math Fluency in Children with Attention-Deficit/Hyperactivity Disorder

OBJECTIVES

(1) To determine the processing speed (PS) deficit in children with ADHD; and (2) To investigate if PS deficit was the primary cause of daily dysfunction in ADHD by testing the direct and indirect effects via working memory (WM) of PS on math fluency (MF).

METHOD

Seventy-eight children (52 children with ADHD and 26 controls) were tested on their motor, perceptual, cognitive, and verbal PS, WM, and MF.

RESULTS

Children with ADHD performed worse than controls on all PS, suggesting a general PS deficit. Moreover, cognitive PS was a significant predictor for MF. Mediation analysis showed that cognitive PS had direct and indirect effects via WM on MF, suggesting PS deficit might be the primary cause of MF difficulties in ADHD.

CONCLUSION

Findings of this study suggested a general PS deficit in ADHD. Due to the importance of PS in MF, interventions for MF underachievers should include assessment and training of PS.

Disentangling racing thoughts from mind wandering in adult attention deficit hyperactivity disorder

Introduction

Mental restlessness reported by adult with Attention Deficit Hyperactivity Disorder (ADHD) has been mainly explained by excessive mind wandering. However, the description of a mind constantly on the go is also akin to racing thoughts, predominantly described in bipolar disorder. This paper aimed at disentangling mind wandering from racing thoughts in adult with ADHD. Associations between those mental phenomena and the ADHD symptomatology were also investigated.

Methods

To this aim, 84 adults with ADHD completed self-reported questionnaires, including the Mind Wandering-Deliberate and Mind Wandering-Spontaneous questionnaires, the Racing and Crowded Thoughts Questionnaire and the Daydreaming Frequency Scale. Factorial analysis and multiple linear regressions were performed.

Results

The factor analysis yielded a two-factor solution. The first factor encompassed the three facets of racing thoughts and was predicted by emotional lability. The second comprised deliberated-MW, spontaneous-MW and daydreaming, but was neither related to the ADHD symptoms, nor functional impairment.

Discussion

These findings suggest that MW and racing thoughts are two distinguishable mental phenomena. Racing thoughts appear to be a relevant hypothesis to explain the mental restlessness in adult ADHD.

Neurocognitive and cerebellar function in ADHD, autism and spinocerebellar ataxia

The cerebellum plays a major role in balance, motor control and sensorimotor integration, but also in cognition, language, and emotional regulation. Several neuropsychiatric disorders such as attention deficit-hyperactivity disorder (ADHD), autism spectrum disorder (ASD), as well as neurological diseases such as spinocerebellar ataxia type 3 (SCA3) are associated with differences in cerebellar function. Morphological abnormalities in different cerebellar subregions produce distinct behavioral symptoms related to the functional disruption of specific cerebro-cerebellar circuits. The specific contribution of the cerebellum to typical development may therefore involve the optimization of the structure and function of cerebro-cerebellar circuits underlying skill acquisition in multiple domains. Here, we review cerebellar structural and functional differences between healthy and patients with ADHD, ASD, and SCA3, and explore how disruption of cerebellar networks affects the neurocognitive functions in these conditions. We discuss how cerebellar computations contribute to performance on cognitive and motor tasks and how cerebellar signals are interfaced with signals from other brain regions during normal and dysfunctional behavior. We conclude that the cerebellum plays a role in many cognitive functions. Still, more clinical studies with the support of neuroimaging are needed to clarify the cerebellum's role in normal and dysfunctional behavior and cognitive functioning.

Exploring the Relationship between Cardiorespiratory Fitness and Executive Functioning in Adults with ADHD

OBJECTIVE

Associations between measures of executive functioning (EF) and cardiorespiratory fitness (CRF) were examined for adults with and without ADHD.

METHOD

Measures of executive functioning including the Stroop task, Wisconsin Card Sorting task, and Operation Span Task were completed virtually (n = 36 ADHD; n = 36 Control). Participants completed the Six-Minute Walk Test to estimate CRF.

RESULTS

Mean performance measures of executive function did not differ by group. However, higher estimated CRF was associated with better Stroop task performance, and the association was strongest for individuals with ADHD.

CONCLUSION

In adults with ADHD, higher estimated CRF was associated with better inhibitory control, but not with other measures of executive functioning.

Time Perception in Adult ADHD: Findings from a Decade-A Review

Time perception is impaired in adult ADHD. Since the term time perception subsumes different constructs, including time estimation, time reproduction, time production, and duration discrimination, it remains open whether certain domains are more affected than other domains in adult ADHD. The aim of this explorative review is to present the current state of research on time perception in adult ADHD by analysing studies from the past 10 years. A review of the literature addressing adult ADHD time perception, time estimation, and time reproduction was performed. The search strategy was conducted by using the databases "PubMed", "Medline", and "PSYNDEX". The results of the present review indicate that the number of studies on time perception in adult ADHD is very scarce. Moreover, the main investigated domains of time perception in the past decade were time estimation, time reproduction and time management. Whereas some of the found studies were able to demonstrate a distinct deficit in time estimation, time reproduction and time management other studies were unable to demonstrate a clear association between ADHD and time estimation and time reproduction deficits. However, the diagnostic protocols, study design, and methodology varied between studies. Further studies on time estimation and time reproduction need to be carried out.

Detecting Early Cognitive Decline in Alzheimer's Disease with Brain Synaptic Structural and Functional Evaluation

Early cognitive decline in patients with Alzheimer's (AD) is associated with quantifiable structural and functional connectivity changes in the brain. AD dysregulation of Aβ and tau metabolism progressively disrupt normal synaptic function, leading to loss of synapses, decreased hippocampal synaptic density and early hippocampal atrophy. Advances in brain imaging techniques in living patients have enabled the transition from clinical signs and symptoms-based AD diagnosis to biomarkers-based diagnosis, with functional brain imaging techniques, quantitative EEG, and body fluids sampling. The hippocampus has a central role in semantic and episodic memory processing. This cognitive function is critically dependent on normal intrahippocampal connections and normal hippocampal functional connectivity with many cortical regions, including the perirhinal and the entorhinal cortex, parahippocampal cortex, association regions in the temporal and parietal lobes, and prefrontal cortex. Therefore, decreased hippocampal synaptic density is reflected in the altered functional connectivity of intrinsic brain networks (aka large-scale networks), including the parietal memory, default mode, and salience networks. This narrative review discusses recent critical issues related to detecting AD-associated early cognitive decline with brain synaptic structural and functional markers in high-risk or neuropsychologically diagnosed patients with subjective cognitive impairment or mild cognitive impairment.

Assessment of learning and memory impairments in adults with predominately inattentive versus combined presentation attention-deficit/hyperactivity disorder

This cross-sectional study compared adults diagnosed with Attention-Deficit/Hyperactivity Disorder-Inattentive (ADHD-I) and ADHD-Combined (ADHD-C) presentations with a non-ADHD group on verbal and visual learning and delayed recall using the Rey Auditory Verbal Learning Test (RAVLT) and Brief Visuospatial Memory Test-Revised (BVMT-R), respectively. Data from 380 predominately college student adult outpatients were used, with 155 who met criteria for ADHD-I, 165 who met criteria for ADHD-C, and 60 who did not meet criteria for ADHD but were diagnosed with a primary depressive or anxiety disorder or received no diagnosis. Each patient was administered the RAVLT and BVMT-R as part of a comprehensive neuropsychological evaluation. Significant main effects of study group were found, such that patients with ADHD-C demonstrated worse learning and delayed recall of both verbal and visual information than patients with ADHD-I and the non-ADHD group. Patients with ADHD-I performed comparably to the non-ADHD group, apart from visual learning and delayed recall. Notably, more patients in the ADHD groups had possible or probable learning and memory impairment compared to the non-ADHD group. Findings were consistent with previous research indicating that those with ADHD exhibit poorer verbal and visual learning and delayed recall than those without ADHD.

Attention Performance as an Embedded Validity Indicator in the Cognitive Assessment of Early Retirement Claimants

The assessment of performance validity is essential in any neuropsychological evaluation. However, relatively few measures exist that are based on attention performance embedded within routine cognitive tasks. The present study explores the potential value of a computerized attention test, the Cognitrone, as an embedded validity indicator in the neuropsychological assessment of early retirement claimants. Two hundred and sixty-five early retirement claimants were assessed with the Word Memory Test (WMT) and the Cognitrone. WMT scores were used as the independent criterion to determine performance validity. Speed and accuracy measures of the Cognitrone were analyzed in receiver operating characteristics (ROC) to classify group membership. The Cognitrone was sensitive in revealing attention deficits in early retirement claimants. Further, 54% (n = 143) of the individuals showed noncredible cognitive performance, whereas 46% (n = 122) showed credible cognitive performance. Individuals failing the performance validity assessment showed slower (AUC = 79.1%) and more inaccurate (AUC = 79.5%) attention performance than those passing the performance validity assessment. A compound score integrating speed and accuracy revealed incremental value as indicated by AUC = 87.9%. Various cut scores are suggested, resulting in equal rates of 80% sensitivity and specificity (cut score = 1.297) or 69% sensitivity with 90% specificity (cut score = 0.734). The present study supports the sensitivity of the Cognitrone for the assessment of attention deficits in early retirement claimants and its potential value as an embedded validity indicator. Further research on different samples and with multidimensional criteria for determining invalid performance are required before clinical application can be suggested.

Stability of Attention Performance of Adults with ADHD over Time: Evidence from Repeated Neuropsychological Assessments in One-Month Intervals

Neuropsychological assessments of attention are valuable sources of information in the clinical evaluation of adults with attention-deficit/hyperactivity disorder (ADHD). However, it is unclear whether the attention performance of adults with ADHD is stable or fluctuates over time, which is of great importance in the interpretation of clinical assessments. This study aimed to explore the stability of attention performance of adults with ADHD in repeated assessments at one-month intervals. Twenty-one adults diagnosed with ADHD took part in this study by completing selective attention and vigilance tests three times, each one month apart. Test scores of participants were compared with and interpreted based on test norms. A considerable proportion of 'below average' performance scores were observed in most of the variables of selective attention and vigilance in all three assessments. Further, selective attention and vigilance performance scores did not differ significantly between the three repeated assessments. Finally, the majority of participants received consistent test score interpretations across the three repeated assessments. This study confirms previous research and highlights abnormal selective attention and vigilance performance in adults with ADHD. Further, this study preliminarily demonstrates relatively stable attention performance across repeated assessments, which has the potential to support clinical assessment, treatment planning, and evaluation.

Networks of Neuropsychological Functions in the Clinical Evaluation of Adult ADHD

This study applied network analysis to explore the relations between neuropsychological functions of individuals in the clinical evaluation of attention-deficit/hyperactivity disorder (ADHD) in adulthood. A total of 319 participants from an outpatient referral context, that is, 173 individuals with ADHD (ADHD group) and 146 individuals without ADHD (n-ADHD group), took part in this study and completed a comprehensive neuropsychological assessment. A denser network with stronger global connectivity was observed in the ADHD group compared to the n-ADHD group. The strongest connections were consistent in both networks, that is, the connections between selective attention and vigilance, and connections between processing speed, fluency, and flexibility. Further centrality estimation revealed attention-related variables to have the highest expected influence in both networks. The observed relationships between neuropsychological functions, and the high centrality of attention, may help identify neuropsychological profiles that are specific to ADHD and optimize neuropsychological assessment and treatment planning of individuals with cognitive impairment.

Allicin, an Antioxidant and Neuroprotective Agent, Ameliorates Cognitive Impairment

Allicin (diallylthiosulfinate) is a defense molecule produced by cellular contents of garlic (Allium sativum L.). On tissue damage, the non-proteinogenic amino acid alliin (S-allylcysteine sulfoxide) is converted to allicin in an enzyme-mediated process catalysed by alliinase. Allicin is hydrophobic in nature, can efficiently cross the cellular membranes and behaves as a reactive sulfur species (RSS) inside the cells. It is physiologically active molecule with the ability to oxidise the thiol groups of glutathione and between cysteine residues in proteins. Allicin has shown anticancer, antimicrobial, antioxidant properties and also serves as an efficient therapeutic agent against cardiovascular diseases. In this context, the present review describes allicin as an antioxidant, and neuroprotective molecule that can ameliorate the cognitive abilities in case of neurodegenerative and neuropsychological disorders. As an antioxidant, allicin fights the reactive oxygen species (ROS) by downregulation of NOX (NADPH oxidizing) enzymes, it can directly interact to reduce the cellular levels of different types of ROS produced by a variety of peroxidases. Most of the neuroprotective actions of allicin are mediated via redox-dependent pathways. Allicin inhibits neuroinflammation by suppressing the ROS production, inhibition of TLR4/MyD88/NF-κB, P38 and JNK pathways. As an inhibitor of cholinesterase and (AChE) and butyrylcholinesterase (BuChE) it can be applied to manage the Alzheimer's disease, helps to maintain the balance of neurotransmitters in case of autism spectrum disorder (ASD) and attention deficit hyperactive syndrome (ADHD). In case of acute traumatic spinal cord injury (SCI) allicin protects neuron damage by regulating inflammation, apoptosis and promoting the expression levels of Nrf2 (nuclear factor erythroid 2-related factor 2). Metal induced neurodegeneration can also be attenuated and cognitive abilities of patients suffering from neurological diseases can be ameliorates by allicin administration.