Objectives: Neuroimaging studies report altered resting-state functional connectivity in attention deficit/hyperactivity disorder (ADHD) across multiple brain systems. However, there is inconsistency among individual studies. Methods: We meta-analyzed seed-based resting state studies of ADHD connectivity within and between four established resting state brain networks (default mode, cognitive control, salience, affective/motivational) using Multilevel Kernel Density Analysis method. Results: Twenty studies with 944 ADHD patients and 1121 controls were included in the analysis. Compared to controls, ADHD was associated with disrupted within-default mode network (DMN) connectivityreduced in the core (i.e. posterior cingulate cortex seed) but elevated in the dorsal medial prefrontal cortex subsystem (i.e. temporal pole-inferior frontal gyrus). Connectivity was elevated between nodes in the cognitive control system. When the analysis was restricted to children and adolescents, additional reduced connectivity was detected between DMN and cognitive control and affective/motivational and salience networks. Conclusions: Our data are consistent with the hypothesis that paediatric ADHD is a DMN-dysconnectivity disorder with reduced connectivity both within the core DMN subsystem and between that system and a broad set of nodes in systems involved in cognition and motivation.

Attention-deficit/hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder and is characterized by symptoms of inattention and/or hyperactivity and impulsivity. In the current study, we obtained quantitative EEG (QEEG) recordings of 51 children aged between 6 and 12 years before the initiation of methylphenidate treatment. The relationship between changes in the scores of ADHD symptoms and initial QEEG features (power/power ratios values) were assessed. In addition, the children were classified as responder and nonresponder according to the ratio of their response to the medication (>25% improvement after medication). Logistic regression analyses were performed to analyze the accuracy of QEEG features for predicting responders. The findings indicate that patients with increased delta power at F8, theta power at Fz, F4, C3, Cz, T5, and gamma power at T6 and decreased beta powers at F8 and P3 showed more improvement in ADHD hyperactivity symptoms. In addition, increased delta/beta power ratio at F8 and theta/beta power ratio at F8, F3, Fz, F4, C3, Cz, P3, and T5 showed negative correlations with Conners’ score difference of hyperactivity as well. This means, those with greater theta/beta and delta/beta powers showed more improvement in hyperactivity following medication. Theta power at Cz and T5 and theta/beta power ratios at C3, Cz, and T5 have significantly classified responders and nonresponders according to the logistic binary regression analysis. The results show that slow and fast oscillations may have predictive value for treatment response in ADHD. Future studies should seek for more sensitive biomarkers.

BackgroundThe relationship between vitamin D and cognitive status remains controversial. We aimed to evaluate the effect of vitamin D replacement on cognitive functions in healthy and cognitively intact vitamin D deficient older females.MethodsThis study was designed as a prospective interventional study. A total of 30 female adults aged ≥60 with a serum 25 (OH) vitamin D level of <10 ng/ml were included. Participants were administered 50 000 IU vitamin D3 weekly for 8 weeks followed by a maintenance therapy of 1000 U/day. Detailed neuropsychological assessment was performed prior to vitamin D replacement and repeated at 6 months by the same psychologist.ResultsMean age was 63 ± 6.7 years and baseline vitamin D level was 7.8 ± 2.0 (range: 3.5–10.3) ng/ml. At 6 months, vitamin D level was 32.5 ± 3.4 (32.2–55) ng/ml. The Judgement of Line Orientation Test (P = 0.04), inaccurate word memorizing of the Verbal Memory Processes Test (P = 0.02), perseveration scores of the Verbal Memory Processes Test (P = 0.005), topographical accuracy of the Warrington Recognition Memory Test (P = 0.002), and the spontaneous self‐correction of an error in the Boston Naming Test (P = 0.003) scores increased significantly, while the delayed recall score in the Verbal Memory Processes Test (P = 0.03), incorrect naming of words in the Boston Naming Test (P = 0.04), interference time of the Stroop Test (P = 0.05), and spontaneous corrections of the Stroop Test (P = 0.02) scores decreased significantly from baseline.ConclusionVitamin D replacement has a positive effect on cognitive domains related to visuospatial, executive, and memory processing functions.

No abstract