Attention deficit hyperactivity disorder (ADHD) is among the most frequent disorders within child and adolescent psychiatry, with a prevalence of over 5%. Nosological systems, such as the Diagnostic ...and Statistical Manual of Mental Disorders, 5th edition (DSM-5) and the International Classification of Diseases, editions 10 and 11 (ICD-10/11) continue to define ADHD according to behavioral criteria, based on observation and on informant reports. Despite an overwhelming body of research on ADHD over the last 10 to 20 years, valid neurobiological markers or other objective criteria that may lead to unequivocal diagnostic classification are still lacking. On the contrary, the concept of ADHD seems to have become broader and more heterogeneous. Thus, the diagnosis and treatment of ADHD are still challenging for clinicians, necessitating increased reliance on their expertise and experience. The first part of this review presents an overview of the current definitions of the disorder (DSM-5, ICD-10/11). Furthermore, it discusses more controversial aspects of the construct of ADHD, including the dimensional versus categorical approach, alternative ADHD constructs, and aspects pertaining to epidemiology and prevalence. The second part focuses on comorbidities, on the difficulty of distinguishing between "primary" and "secondary" ADHD for purposes of differential diagnosis, and on clinical diagnostic procedures. In the third and most prominent part, an overview of current neurobiological concepts of ADHD is given, including neuropsychological and neurophysiological researches and summaries of current neuroimaging and genetic studies. Finally, treatment options are reviewed, including a discussion of multimodal, pharmacological, and nonpharmacological interventions and their evidence base.
The objective our study was to carry out a systematic review and meta-analysis to examine the impact of attention-deficit and hyperactivity disorder (ADHD) on bariatric surgery outcomes. Despite the ...effectiveness of bariatric surgery, about 10 to 20% of patients continue to regain weight after the procedure. New evidence supports that ADHD may be directly associated with obesity and may affect outcomes following bariatric surgery. However, certain psychiatric illnesses, such as ADHD, are rarely screened for, leading to a continued lack of data on the interaction between ADHD and bariatric surgery. A comprehensive literature search for both published and unpublished studies of ADHD and bariatric surgery from 1946 to August 2018 was performed. The search was conducted using the Medline, EMBASE, Scopus, the Cochrane Library, and Web of Science databases as well as conference abstracts. Our search strategy terms included “(ADHD OR attention deficit hyperactivity disorder) AND (bariatrics OR obesity surgery OR gastric bypass OR gastric sleeve OR Roux-en-Y OR RYGB OR sleeve gastrectomy)” and was limited to human studies in the English language. Preliminary database search of the literature yielded 104 articles after 70 duplicates were removed. A total of five studies with 492 patients were included. The overall ADHD rate was 20.9% with reported rates ranging from 7 to 38%. The weighted mean age was 44.0 ± 10.2 years, the weighted sex was 83.6% female, and the weighted mean follow-up was 22.2 months. Preoperative weighted mean BMI was 43.7 versus a postoperative weighted mean BMI of 34.7. No statistical significance was observed for mean BMI difference between non-ADHD vs. ADHD patients undergoing bariatric surgery (three studies; MD − 2.66; CI − 7.54 to 2.13;
p
= 0.28). Statistical significance was, however, observed for postoperative follow-up between patients with ADHD vs. non-ADHD subjects (three studies; MD − 7.28; − 13.83 to −0.73;
p
= 0.03). Patients with ADHD do not have a statistically significant mean BMI difference following bariatric surgery but have a statistically significant reduction in postoperative follow-up versus non-ADHD patients. Targeted strategies aimed at improving clinic attendance for this at-risk ADHD population may improve bariatric outcomes and minimize recidivism rates.
Neuroimaging studies have revealed neurobiological differences in ADHD, particularly studies examining connectivity disruption and anatomical network organization. However, the underlying ...pathophysiology of ADHD types remains elusive as it is unclear whether dysfunctional network connections characterize the underlying clinical symptoms distinguishing ADHD types. Here, we investigated intrinsic functional network connectivity to identify neural signatures that differentiate the combined (ADHD-C) and inattentive (ADHD-I) presentation types. Applying network-based statistical (NBS) and graph theoretical analysis to task-derived intrinsic connectivity data from completed fMRI scans, we evaluated default mode network (DMN) and whole-brain functional network topology in a cohort of 34 ADHD participants (aged 8–17 years) defined using DSM-IV criteria as predominantly inattentive (ADHD-I) type (
n
= 15) or combined (ADHD-C) type (
n
= 19), and 39 age and gender-matched typically developing controls. ADHD-C were characterized from ADHD-I by reduced network connectivity differences within the DMN. Additionally, reduced connectivity within the DMN was negatively associated with ADHD-RS hyperactivity-impulsivity subscale score. Compared with controls, ADHD-C but not ADHD-I differed by reduced connectivity within the DMN; inter-network connectivity between the DMN and somatomotor networks; the DMN and limbic networks; and between the somatomotor and cingulo-frontoparietal, with ventral attention and dorsal attention networks. However, graph-theoretical measures did not significantly differ between groups. These findings provide insight into the intrinsic networks underlying phenotypic differences between ADHD types. Furthermore, these intrinsic functional connectomic signatures support neurobiological differences underlying clinical variations in ADHD presentations, specifically reduced within and between functional connectivity of the DMN in the ADHD-C type.
•Children with attention-deficit/hyperactivity disorder exhibited an increased cortical volume in the left frontal eye field, a decreased surface area in the left ventral frontal cortex, and a ...reduced subcortical volume in the right putamen.•There were significant age-related differences in the left frontal eye field and ventral frontal cortex between the two groups.•This study characterized the cortical morphometry of children with ADHD at the whole brain level providing detailed information about neuroanatomical alterations beyond previous region-of-interest studies.
The current study was designed to investigate the anatomical differences in cortical and subcortical morphometry between drug-naive boys with attention-deficit/hyperactivity disorder (ADHD) and healthy controls (HCs) using three-dimensional T1-weighted imaging and to explore the effects of age on morphometric abnormalities.
Fifty-three drug-naive boys with ADHD and 53 HCs underwent high-resolution anatomical magnetic resonance (MR) imaging using a 3-T MR scanner. The FreeSurfer image analysis suite was used to obtain measures of cortical volume, thickness, and surface area, as well as the volumes of 14 subcortical structures. Statistically significant differences in measures between children with ADHD and HCs were evaluated using a least general linear model, with the intracranial volume and age as covariates.
Compared to HCs, boys with ADHD exhibited an increased cortical volume in the left frontal eye field (FEF), a decreased surface area in the left ventral frontal cortex (VFC), and a decreased volume in the right putamen (cluster-wise p < 0.05; Monte Carlo-corrected). Moreover, we also observed age-related differences in FEF and VFC between groups.
The cross-sectional study design limited inferences about the effects of age on regions displaying morphometric differences.
To our knowledge, this study is the first to characterize the cortical morphometry, including volume, thickness and surface area, of drug-naive boys with ADHD at the whole brain level; which provided detailed information about neuroanatomical alterations in attention systems beyond effects reported in previous studies at the lobe and sub-lobe levels. Based on our results, boys with ADHD presented significant alterations in cortical and subcortical morphology in several important nodes of the attention network.
•Altered brain white matter asymmetry was identified in children with ADHD.•White matter asymmetry was shown to be correlated with ADHD symptom scores regardless of disease status.•The identified ...asymmetric white matter integrity was also related to inhibition function.
We aimed to examine brain white matter integrity in children with ADHD.
In a cohort of children with ADHD (n = 83) and healthy controls (n = 122), we used tract-based spatial statistics on Diffusion Tensor Imaging (DTI) data to obtain the mean fractional anisotropy (FA) in 40 bilateral regions of interest (ROIs). Lateralization Index (LI) was calculated. The difference in LI between groups and correlations between the LI of each ROI and ADHD symptom scores as well as cognitive function were examined.
Children with ADHD had significantly greater LI at the posterior thalamic radiation (PTR) compared with healthy controls (mean LI in ADHD = 0.0096; in Control = 0.0044, p = 0.0143), and LI of the external capsule (EC) was significantly correlated with inattention symptoms in both groups (β = −0.00059, p = 0.0181). LI of the PTR was significantly correlated with inhibitory function in healthy controls (β = −0.0008510, p = 0.0248), but not in children with ADHD.
We found increased brain white matter asymmetry (leftward) in children with ADHD compared with healthy controls at the posterior thalamic radiation. Leftward lateralization of FA values at the external capsule was negatively correlated with ADHD symptoms in both children with ADHD and healthy controls.
•Excessive, spontaneous mind wandering is associated with attention deficit hyperactivity disorder (ADHD).•Deficient regulation of the default mode network in ADHD might lead to this type of mind ...wandering.•This neural dysregulation might also underpin inattention and deficient cognitive performance.•Converging evidence draws parallels between regulatory processes of mind wandering and deficient regulation in ADHD.
Attention-Deficit/Hyperactivity Disorder (ADHD) is a common neurodevelopmental disorder associated with a range of mental health, neurocognitive and functional problems. Although the diagnosis is based on descriptions of behaviour, individuals with ADHD characteristically describe excessive spontaneous mind wandering (MW). MW in individuals with ADHD reflects constant mental activity which lacks topic stability and content consistency. Based on this review of the neural correlates of ADHD and MW, we outline a new perspective on ADHD: the MW hypothesis. We propose that altered deactivation of the default mode network, and dysfunctional interaction with the executive control network, leads to excessive and spontaneous MW, which underpins symptoms and impairments of ADHD. We highlight that processes linked to the normal neural regulation of MW (context regulation, sensory decoupling, salience thresholds) are deficient in ADHD. MW-related measures could serve as markers of the disease process, as MW can be experimentally manipulated, as well as measured using rating scales, and experience sampling during both cognitive tasks and daily life. MW may therefore be a potential endophenotype.
Problems with executive functions (EF) are hallmark characteristics of Attention Deficit/Hyperactivity Disorder (ADHD). Therefore, this review analyzed the efficacy of cognitive training for EF in ...reducing ADHD symptomatology and improving educational, interpersonal, and occupational outcomes in children and adolescents with this disorder. A systematic search, using a PICO (population/participant, intervention/indicator, comparator/control, outcome) framework was carried out. From 2008 to 2018, resorting to EBSCO
, the following databases were searched: Academic Search Complete, ERIC, MEDLINE with Full Text, PsycARTICLES, PsycINFO, and Psychology and Behavioral Sciences Collection. Twenty-two studies were included in this review. Of the 18 studies that reported performance-based measures of EF, 13 found improvements and five did not. Overall, 17 studies showed positive transfer effects on ADHD symptomatology, EF, academic improvement, reduced off-task behavior, and/or enhanced social skills. Of the nine studies that performed follow-up sessions, seven concluded that the treatment effects were maintained over time. In sum, results showed that cognitive training can be an effective intervention for children and adolescents with ADHD and might be a complementary treatment option for this disorder.
Objective: The objective was to reveal the relationship between dose and concentration of atomoxetine. Method: Fifty-five blood samples of 33 patients with ADHD were examined using high-performance ...liquid chromatography. Results: The plasma concentrations were 53.2 ± 67.0, 298.0 ± 390.5, and 639.3 ± 831.9 ng/mL at doses of 40 mg, 80 mg, and 120 mg, and the concentration/dose were 1.33 ± 1.67, 3.73 ± 4.88, and 5.33 ± 6.93 ng/mL/mg, respectively. Statistical analyses revealed a significant correlation between the concentration and the dose of atomoxetine (p = .004), and a trending toward significance in the difference in the concentration/dose in the three dosage groups (p = .064). The concentration/dose at 40 and 80 + 120 mg/day were 1.33 ± 1.67 and 4.22 ± 5.53 ng/mL/mg, the latter was significantly higher than the former (p = .006), which suggested non-linear pharmacokinetics. Conclusion: Clinicians should carefully titrate in high dose atomoxetine treatment.
This article shows how adding a second step of windowing after each phase randomization can reduce the false rejection rate in the Fourier-based surrogate analysis (SA). Windowing techniques reduce ...the discontinuities at the boundaries of the periodically extended data sequence in the Fourier Series. However, they add time-domain nonstationarity that affects the SA. This effect is particularly problematic for short low-pass signals. Applying the same window to the surrogate data allows having the same nonstationarity. The method is tested on order 1 autoregressive process null hypothesis by Monte Carlo simulations. Previous methods were not able to yield good performances for left- and right-sided tests at the same time, even less with bilateral tests. It is shown that the new method is conservative for unilateral tests and bilateral tests. In order to show that the proposed windowing method can be useful in the real context, in this extended paper, it was applied for an electroencephalogram (EEG) diagnostic problem. A dataset comprising the EEG measurements of 15 subjects distributed in three groups, attention-deficit disorder primarily hyperactive-impulsive (ADHD), attention-deficit disorder primarily inattentive (ADD), and anxiety with attentional fragility (ANX), was used. Both statistical and machine learning (naïve Bayesian) approaches were considered. The mean short-windowed SA (MSWSA) was used as a signal feature, and its performances were studied with respect to the windowing systems. The main findings were that: 1) the MSWSA feature has less variability for ADD than for ADHD or ANX; 2) the proposed windowing method reduces bias and nonnormality of the SA feature; 3) with the proposed method and a naïve Bayesian classifier, a 93% success rate of discriminating ADD from ADHD and ANX was achieved with leave-one-out cross-validation; and 4) the new feature could not have yielded interesting results without the proposed windowing system.
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