Structural connectivity in adolescent synthetic cannabinoid users with and without ADHD

White matter alterations in Attention-Deficit/Hyperactivity Disorder (ADHD): a systematic review of 129 diffusion imaging studies with meta-analysis

Aberrant anatomical brain connections in attention-deficit/hyperactivity disorder (ADHD) are reported inconsistently across diffusion weighted imaging (DWI) studies. Based on a pre-registered protocol (Prospero: CRD42021259192), we searched PubMed, Ovid, and Web of Knowledge until 26/03/2022 to conduct a systematic review of DWI studies. We performed a quality assessment based on imaging acquisition, preprocessing, and analysis. Using signed differential mapping, we meta-analyzed a subset of the retrieved studies amenable to quantitative evidence synthesis, i.e., tract-based spatial statistics (TBSS) studies, in individuals of any age and, separately, in children, adults, and high-quality datasets. Finally, we conducted meta-regressions to test the effect of age, sex, and medication-naïvety. We included 129 studies (6739 ADHD participants and 6476 controls), of which 25 TBSS studies provided peak coordinates for case-control differences in fractional anisotropy (FA)(32 datasets) and 18 in mean diffusivity (MD)(23 datasets). The systematic review highlighted white matter alterations (especially reduced FA) in projection, commissural and association pathways of individuals with ADHD, which were associated with symptom severity and cognitive deficits. The meta-analysis showed a consistent reduced FA in the splenium and body of the corpus callosum, extending to the cingulum. Lower FA was related to older age, and case-control differences did not survive in the pediatric meta-analysis. About 68% of studies were of low quality, mainly due to acquisitions with non-isotropic voxels or lack of motion correction; and the sensitivity analysis in high-quality datasets yielded no significant results. Findings suggest prominent alterations in posterior interhemispheric connections subserving cognitive and motor functions affected in ADHD, although these might be influenced by non-optimal acquisition parameters/preprocessing. Absence of findings in children may be related to the late development of callosal fibers, which may enhance case-control differences in adulthood. Clinicodemographic and methodological differences were major barriers to consistency and comparability among studies, and should be addressed in future investigations.

Altered brain structural and functional connectivity in cannabis users

Cannabis is one of the most used and commodified illicit substances worldwide, especially among young adults. The neurobiology mechanism of cannabis is yet to be identified particularly in youth. The purpose of this study was to concurrently measure alterations in brain structural and functional connectivity in cannabis users using resting-state functional magnetic resonance images (rs-fMRI) and diffusion-weighted images (DWI) from a group of 73 cannabis users (age 22-36, 19 female) in comparison with 73 healthy controls (age 22-36, 14 female) from Human Connectome Project (HCP). Several significant differences were observed in local structural/functional network measures (e.g. degree and clustering coefficient), being prominent in the insular and frontal opercular cortex and lateral/medial temporal cortex. The rich-club organization of structural networks revealed a normal trend, distributed within bilateral frontal, temporal and occipital regions. However, minor differences were found between the two groups in the superior and inferior temporal gyri. Functional rich-club nodes were mostly located within parietal and posterior areas, with minor differences between the groups found mainly in the centro-temporal and parietal regions. Regional network measures of structural/functional networks were associated with times used cannabis (TUC) in several regions. Although the structural/functional network in both groups showed small-world property, no differences between cannabis users and healthy controls were found regarding the global network measures, showing no association with cannabis use. After FDR correction, all of the significant associations between network measures and TUC were found to be insignificant, except for the association between degree and TUC within the presubiculum region. To recap, our findings revealed alterations in local topological properties of structural and functional networks in cannabis users, although their global brain network organization remained intact.

Risk behaviors in substance use disorder in a sample of Egyptian female patients with or without symptoms of attention-deficit hyperactivity disorder

Background

Risk-taking behaviors are associated with attention-deficit hyperactivity disorder (ADHD) and substance use disorder (SUD). Individuals with both diagnoses have been reported to have an earlier onset, a longer course, and greater severity, with more relapses and greater difficulty remaining abstinent.

The current study was assessing females seeking treatment for SUDs for the presence of comorbid ADHD, to investigate the association between severity of SUD and co-occurring ADHD symptoms and to examine related risk behaviors. Therefore, thirty female patients were enrolled, and demographic data was collected. Participants were interviewed by SCID I, addiction severity index, Arabic-translated and validated version of the adult ADHD Self-Report Scale Barratt Impulsiveness Scale Version 11, and Arabic version of the Adult Scale of Hostility and Aggression.

Results

Thirty female patients were included in the study, and 33.3% had extreme severity, on the addiction severity index scale. Fifteen patients had ADHD symptoms; 33.3% had high likely scores, according to Adult ADHD Self-Reported Scale (ASRS). There is a significant difference regarding the age of onset of substance use and smoking (P = 0.029), first sexual activity (P = 0.002), number of sexual partners (P = 0.009), impairment in employment, and family and social relationships items (P = 0.024, P = 0.028, respectively) in SUD patients with ADHD symptoms than in SUD patients without ADHD symptoms.

Conclusion

Female patients diagnosed with adult ADHD have an earlier age of smoking and substance use, having first sexual activity at younger age, and having more sexual partners with more employment, family, and social relationship problems.

Cannabis use in Attention - Deficit/Hyperactivity Disorder (ADHD): A scoping review

INTRODUCTION

Treatments for Adult ADHD include stimulants, two non-stimulant medications, as well as cognitive-behavioral therapy (CBT). These pharmacological agents are often associated with side effects, contributing to poor treatment adherence. Patients with ADHD have regularly stated that cannabis has helped improve their ADHD symptoms; however, scientific literature describing the effects of cannabis on symptoms of ADHD is scarce.

METHODS

We systematically searched MEDLINE, EMBASE, EMCARE, PsycINFO, Web of Science, Cochrane Library, and Clinicaltrials.gov. The searches included all publications in English up to June 27, 2022. We included both experimental and observational studies that assessed the effect of cannabis on ADHD symptomatology and neuropsychiatric outcomes. To synthesize our current understanding of the potential effects of cannabis use on ADHD symptoms and pathophysiology, and the effects of ADHD on cannabis use, data was extracted from each study regarding the characteristics of its population, methods used to assess both cannabis consumption and ADHD symptoms, and key findings.

RESULTS

Our scoping review included a total of 39 studies. Only one study employed a randomized and placebo-controlled design to directly measure the effect of cannabis on ADHD, and no significant effect was observed for the study's primary outcome, the QbTest (Est = -0.17, 95% CI -0.40 to 0.07, p = 0.16). Most of the literature consists of cross-sectional studies that evaluate the association between ADHD severity and cannabis use. 15 studies addressed the neuropsychiatric effects of cannabis on ADHD by employing either a battery of neuropsychiatric tests or neuroimaging. The concentration and amount of THC and CBD used were not well measured in most of the studies. Although some studies indicated that cannabis improved ADHD symptoms, most studies indicated it worsened or had no effect on ADHD symptoms.

CONCLUSIONS

Given the current evidence, cannabis is not recommended for people with ADHD. Limitations of the literature include the absence of objective measurements for cannabis exposure and ADHD symptoms, heterogenous definitions, oversampling, and small sample sizes.

The relationship between reading abilities and the left occipitotemporal sulcus: A dual perspective study

Reading activates a region within the left lateral occipitotemporal sulcus (OTS) known as the 'visual word form area' (VWFA). While several studies have investigated the impact of reading on brain structure through neuroplastic mechanisms, it has been recently suggested that individual differences in the pattern of the posterior OTS may predict reading skills in adults. In the present study, we first examined whether the structure and morphology and the anatomical connectivity of the left OTS are associated to reading ability. Second, we explored whether reading skills are predicted by the pattern of the left OTS. We found that reading skills were positively associated with increased connectivity between the left OTS and a network of reading-related regions in the left hemisphere. On the other hand, we did not observe an association between the pattern of the left OTS and reading skills. Finally, we found evidence that the morphology and the connectivity of the left OTS are correlated to its sulcal pattern.

Abnormal resting-state functional connectome in methamphetamine-dependent patients and its application in machine-learning-based classification

Brain resting-state functional connectivity (rsFC) has been widely analyzed in substance use disorders (SUDs), including methamphetamine (MA) dependence. Most of these studies utilized Pearson correlation analysis to assess rsFC, which cannot determine whether two brain regions are connected by direct or indirect pathways. Moreover, few studies have reported the application of rsFC-based graph theory in MA dependence. We evaluated alterations in Tikhonov regularization-based rsFC and rsFC-based topological attributes in 46 MA-dependent patients, as well as the correlations between topological attributes and clinical variables. Moreover, the topological attributes selected by least absolute shrinkage and selection operator (LASSO) were used to construct a support vector machine (SVM)-based classifier for MA dependence. The MA group presented a subnetwork with increased rsFC, indicating overactivation of the reward circuit that makes patients very sensitive to drug-related visual cues, and a subnetwork with decreased rsFC suggesting aberrant synchronized spontaneous activity in subregions within the orbitofrontal cortex (OFC) system. The MA group demonstrated a significantly decreased area under the curve (AUC) for the clustering coefficient (Cp) (Pperm < 0.001), shortest path length (Lp) (Pperm = 0.007), modularity (Pperm = 0.006), and small-worldness (σ, Pperm = 0.004), as well as an increased AUC for global efficiency (E.glob) (Pperm = 0.009), network strength (Sp) (Pperm = 0.009), and small-worldness (ω, Pperm < 0.001), implying a shift toward random networks. MA-related increased nodal efficiency (E.nodal) and altered betweenness centrality were also discovered in several brain regions. The AUC for ω was significantly positively associated with psychiatric symptoms. An SVM classifier trained by 36 features selected by LASSO from all topological attributes achieved excellent performance, cross-validated prediction area under the receiver operating characteristics curve, accuracy, sensitivity, specificity, and kappa of 99.03 ± 1.79, 94.00 ± 5.78, 93.46 ± 8.82, 94.52 ± 8.11, and 87.99 ± 11.57%, respectively (Pperm < 0.001), indicating that rsFC-based topological attributes can provide promising features for constructing a high-efficacy classifier for MA dependence.

Reduced Modular Segregation of White Matter Brain Networks in Attention Deficit Hyperactivity Disorder

OBJECTIVE

Despite studies reporting alterations in the brain networks of patients with ADHD, alterations in the modularity of white matter (WM) networks are still unclear.

METHOD

Based on the results of module division by generalized Louvain algorithm, the modularity of ADHD was evaluated. The correlation between the modular changes of ADHD and its clinical characteristics was analyzed.

RESULTS

The participation coefficient and the connectivity between modules of ADHD increased, and the modularity coefficient decreased. Provincial hubs of ADHD did not change, and the number of connector hubs increased. All results showed that the modular segregation of WM networks of ADHD decreased. Modules with reduced modular segregation are mainly responsible for language and motor functions. Moreover, modularity showed evident correlation with the symptoms of ADHD.

CONCLUSION

The modularity changes in WM network provided a novel insight into the understanding of brain cognitive alterations in ADHD.

Consumption of Synthetic Cannabinoids in Adult Attention-Deficit/Hyperactivity Disorder: a Pilot Study

Attention-deficit/hyperactivity disorder (ADHD) is associated with an increased risk for substance abuse and addiction. Synthetic cannabinoids (SC) have gained rising importance as their consumption increased rapidly in the last few years. However, SC consumption in patients with adult ADHD has not been investigated yet. A prospective clinical pilot study was conducted, including 60 adults with ADHD, assessing the prevalence of SC consumption and its associations with psychiatric comorbidities and patient characteristics. A drug consumption survey was utilized to investigate the use of SC and other drugs. Current ADHD symptoms were evaluated via ADHD Self-Rating Scale (ADHD-SR) and retrospective childhood ADHD symptom severity via Wender Utah Rating Scale (WURS-k) questionnaire. A positive lifetime prevalence of SC consumption was found in 15.0% of the analyzed sample. SC consumption was significantly associated with current smoking, lifetime use of natural cannabis (NC), cocaine, amphetamines, and benzodiazepines. Lifetime NC consumption was indicated by 65.0% and found to antecede SC use in adult ADHD patients. Logistic regression analysis identified substance use disorder and male sex as predictive for SC consumption. Patients with history of SC use scored significantly higher in both WURS-k and ADHD-SR questionnaire compared with nonusers and suffered significantly more frequently from psychiatric comorbidities. Main side-effects of SC included gastrointestinal, cardiovascular, and neuropsychiatric symptoms. SC consumption in adults with ADHD is frequent and associated with stronger ADHD symptom severity. Given the underestimated dangerous effects and related comorbidities, SC use should be subject to scrutiny by clinicians treating ADHD patients. More studies are needed to further elucidate the impact of SC use in ADHD.

Resting state functional connectivity in adolescent synthetic cannabinoid users with and without attention-deficit/hyperactivity disorder

OBJECTIVE

Synthetic cannabinoids (SCs) have become increasingly popular in recent years, especially among adolescents. The first aim of the current study was to examine resting-state functional connectivity (rsFC) in SC users compared to controls. Our second aim was to examine the influence of comorbid attention-deficit/hyperactivity disorder (ADHD) symptomatology on rsFC changes in SC users compared to controls.

METHODS

Resting-state functional magnetic resonance imaging (fMRI) analysis included 25 SC users (14 without ADHD and 11 with ADHD combined type) and 12 control subjects.

RESULTS

We found (i) higher rsFC between the default mode network (DMN) and salience network, dorsal attention network and cingulo-opercular network, and (ii) lower rsFC within the DMN and between the DMN and visual network in SC users compared to controls. There were no significant differences between SC users with ADHD and controls, nor were there any significant differences between SC users with and without ADHD.

CONCLUSIONS

We found the first evidence of abnormalities within and between resting state networks in adolescent SC users without ADHD. In contrast, SC users with ADHD showed no differences compared to controls. These results suggest that comorbidity of ADHD and substance dependence may show different rsFC alterations than substance use alone.

Topological Alterations in White Matter Structural Networks in Blepharospasm

BACKGROUND

Accumulating evidence indicates regional structural changes in the white matter (WM) of brains in patients with blepharospasm (BSP); however, whether large-scale WM structural networks undergo widespread reorganization in these patients remains unclear.

OBJECTIVE

We investigated topology changes and global and local features of large-scale WM structural networks in BSP patients compared with hemifacial spasm (HFS) patients or healthy controls (HCs).

METHODS

This cross-sectional study applied graph theoretical analysis to assess deterministic diffusion tensor tractography findings in 41 BSP patients, 41 HFS patients, and 41 HCs. WM structural connectivity in 246 cortical and subcortical regions was assessed, and topological parameters of the resulting graphs were calculated. Networks were compared among BSP, HFS, and HCs groups.

RESULTS

Compared to HCs, both BSP and HFS patients showed alterations in network integration and segregation characterized by increased global efficiency and modularity and reduced shortest path length. Moreover, increased nodal efficiency in multiple cortical and subcortical regions was found in BSP and HFS patients compared with HCs. However, these differences were not found between BSP and HFS patients. Whereas all participants showed highly similar hub distribution patterns, BSP patients had additional hub regions not present in either HFS patients or HCs, which were located in the primary head and face motor cortex and basal ganglia.

CONCLUSIONS

Our findings suggest that the large-scale WM structural network undergoes an extensive reorganization in BSP, probably due to both dystonia-specific abnormalities and facial hyperkinetic movements. © 2021 International Parkinson and Movement Disorder Society.

Transdiagnostic neuroimaging of reward system phenotypes in ADHD and comorbid disorders

ADHD is a disorder characterized by changes in the reward system and which is highly comorbid with other mental disorders, suggesting common neurobiological pathways. Transdiagnostic neuroimaging findings could help to understand whether a dysregulated reward pathway might be the actual link between ADHD and its comorbidities. We here synthesize ADHD neuroimaging findings on the reward system with findings in obesity, depression, and substance use disorder including their comorbid appearance regarding neuroanatomical features (structural MRI) and activation patterns (resting-state and functional MRI). We focus on findings from monetary-incentive-delay (MID) and delay-discounting (DD) tasks and then review data on striatal connectivity and volumetry. Next, for better understanding of comorbidity in adult ADHD, we discuss these neuroimaging features in ADHD, obesity, depression and substance use disorder and ask whether ADHD heterogeneity and comorbidity are reflected by a common dysregulation in the reward system. Finally, we highlight conceptual issues related to heterogeneous paradigms, different phenotyping, longitudinal prediction and highlight some promising future directions for using striatal reward functioning as a clinical biomarker.

Investigation of Brain Functional Networks in Children Suffering from Attention Deficit Hyperactivity Disorder

ADHD defects the recognition of facial emotions. This study assesses the neurophysiological differences between children with ADHD and matched healthy controls during a face emotional recognition task. The study also explores how brain connectivity is affected by ADHD. Electroencephalogram (EEG) signals were recorded from 64 scalp electrodes. Event-related phase coherence (ERPCOH) method was applied to pre-processed signals, and functional connectivity between any pair of electrodes was computed in different frequency bands. A logistic regression (LR) classifier with elastic net regularization (ENR) was trained to classify ADHD and HC participants using the functional connectivity of frequency bands as a potential biomarker. Subsequently, the brain network is constructed using graph-theoretic techniques, and graph indices such as clustering coefficient (C) and shortest path length (L) were calculated. Significant intra-hemispheric and the inter-hemispheric discrepancy between ADHD and healthy control (HC) groups in the beta band was observed. The graph features indicate that the clustering coefficient is significantly higher in the ADHD group than that in the HC group. At the same time, the shortest path length is significantly lower in the beta band. ADHD's brain networks have a problem in transferring information among various neural regions, which can cause a deficiency in the processing of facial emotions. The beta band seems better to reflect the differences between ADHD and HC. The observed functional connectivity and graph differences could also be helpful in ADHD investigations.