Disturbed corpus callosum microstructure in the presence of normal volume characterizes patients with adult ADHD

Background: Microstructural changes and volume reductions in the corpus callosum (CC) are implicated in childhood ADHD. There are however indications that, in adulthood ADHD, reduced white matter integrity is persistent whereas CC volume normalizes. Our goal was to investigate this in a relatively large adult ADHD sample. In addition to commonly used fractional anisotropy (FA) and mean diffusivity (MD), we calculated parallel (axial diffusion; AD) and perpendicular (radial diffusion; RD) diffusivities to white matter tracts which may offer additional information regarding tissue microstructure. Methods: White matter integrity and volume of the CC were investigated in 87 adult ADHD patients and 98 matched controls. We used diffusion tensor imaging in conjunction with tract-based spatial statistics to examine FA, MD, AD and RD within the genu, body and splenium of the CC. Volumetrics of the CC and its subdivisions were determined using FreeSurfer software. Results: The body of the CC showed lower FA (p = .005) and higher MD (p = .019) and RD (p = .008) values in ADHD patients, compared to controls. Volume of the CC did not differ between the groups (p = .633). Conclusions: Our findings show that callosal volume becomes normal while disturbed white matter integrity of the CC is persistent in adult ADHD. Abnormalities in the body of the CC, the subdivision that contains the commissural fibers connecting the somatosensory, auditory and motor areas may play an important role in the pathophysiology of ADHD

Diminished modulation of preparatory sensorimotor mu rhythm predicts attention-deficit hyperactivity disorder severity

BackgroundAttention-deficit/hyperactivity disorder (ADHD) is characterized by problems in regulating attention and in suppressing disruptive motor activity, i.e. hyperactivity and impulsivity. We recently found evidence that aberrant distribution of posterior α band oscillations (8–12 Hz) is associated with attentional problems in ADHD. The sensorimotor cortex also produces strong 8–12 Hz band oscillations, namely the μ rhythm, and is thought to have a similar inhibitory function. Here, we now investigate whether problems in distributing α band oscillations in ADHD generalize to the μ rhythm in the sensorimotor domain.MethodIn a group of adult ADHD (n = 17) and healthy control subjects (n = 18; aged 21–40 years) oscillatory brain activity was recorded using magnetoencephalography during a visuo-spatial attention task. Subjects had to anticipate a target with unpredictable timing and respond by pressing a button.ResultsPreparing a motor response, the ADHD group failed to increase hemispheric μ lateralization with relatively higher μ power in sensorimotor regions not engaged in the task, as the controls did (F1,33 = 8.70, p = 0.006). Moreover, the ADHD group pre-response μ lateralization not only correlated positively with accuracy (rs = 0.64, p = 0.0052) and negatively with intra-individual reaction time variability (rs = −0.52, p = 0.033), but it also correlated negatively with the score on an ADHD rating scale (rs = −0.53, p = 0.028).ConclusionsWe suggest that ADHD is associated with an inability to sufficiently inhibit task-irrelevant sensorimotor areas by means of modulating μ oscillatory activity. This could explain disruptive motor activity in ADHD. These results provide further evidence that impaired modulation of α band oscillations is involved in the pathogenesis of ADHD.</jats:sec

Human subcortical brain asymmetries in 15,847 people worldwide reveal effects of age and sex

The two hemispheres of the human brain differ functionally and structurally. Despite over a century of research, the extent to which brain asymmetry is influenced by sex, handedness, age, and genetic factors is still controversial. Here we present the largest ever analysis of subcortical brain asymmetries, in a harmonized multi-site study using meta-analysis methods. Volumetric asymmetry of seven subcortical structures was assessed in 15,847 MRI scans from 52 datasets worldwide. There were sex differences in the asymmetry of the globus pallidus and putamen. Heritability estimates, derived from 1170 subjects belonging to 71 extended pedigrees, revealed that additive genetic factors influenced the asymmetry of these two structures and that of the hippocampus and thalamus. Handedness had no detectable effect on subcortical asymmetries, even in this unprecedented sample size, but the asymmetry of the putamen varied with age. Genetic drivers of asymmetry in the hippocampus, thalamus and basal ganglia may affect variability in human cognition, including susceptibility to psychiatric disorders

Het nemen van beslissingen door volwassenen met ADHD:Een systematisch literatuuronderzoek

Personen met aandachtstekortstoornis met hyperactiviteit (ADHD) hebben een grotere kans om minder goede (levens)beslissingen te nemen en om risicovolle activiteiten te ondernemen dan personen zonder ADHD. Mogelijk komt dit doordat de kenmerken van ADHD van invloed zijn op het besluitvormingsproces. Hoewel beslissingsproblematiek reeds uitgebreid is onderzocht bij kinderen en adolescenten met ADHD, is er nog relatief weinig bekend over de besluitvorming van volwassenen met ADHD. Om die reden was het doel van dit literatuuronderzoek de aard en omvang van eventuele tekorten in het besluitvormingsproces van volwassenen met ADHD vast te stellen. Hiertoe is de bestaande literatuur, waarin de prestatie van volwassenen met ADHD op beslissingstaken werd vergeleken met de prestatie van een gezonde controlegroep, systematisch doorzocht, waartoe de databases PsycINFO, MEDLINE en PubMed zijn geraadpleegd. In totaal werden er 31 studies geïncludeerd. In de meerderheid van de studies (i.e. 55 %) weken de prestaties van volwassenen met ADHD af op een of meer van de gebruikte beslissingstaken in vergelijking met de controlegroep(en). Dit literatuuronderzoek levert daarmee voorzichtig bewijs voor het bestaan van verschillen in het besluitvormingsproces tussen gezonde individuen en volwassenen met ADHD. De grote inconsistentie in de bevindingen wordt deels verklaard door de verscheidenheid aan domeinen van besluitvorming die werden onderzocht, de comorbide stoornissen van de participanten en het medicatiegebruik in de ADHD-groepen. Het literatuuronderzoek besluit met een bespreking van de implicaties die de bevindingen hebben voor theorieën over de onderliggende mechanismen van ADHD

Vitamin D supplementation in young children: associations with Theory of Planned Behaviour variables, descriptive norms, moral norms and habits.

OBJECTIVE: In the Netherlands, a supplementation of 10 mug vitamin D is recommended for children (aged 0-4 years), given that vitamin D contributes to the development of healthy bones and deficiency during childhood is a risk factor for osteoporosis at a later age. However, only 60 % of the Dutch children receive sufficient vitamin D supplementation a day. In order to develop interventions to improve supplementation intake, it is necessary to gain insight into the behaviour of parents in giving their children vitamin D supplementation and its association with variables of the Theory of Planned Behaviour, moral and descriptive norms and habits. DESIGN: A cross-sectional survey to assess present supplementation-related behaviour, knowledge, received information, intention, attitude, subjective norm, perceived behavioural control, moral norm, descriptive norm and habit. SETTING: Data obtained from a representative Internet Panel by means of electronic questionnaires. SUBJECTS: Parents (n 270) of children aged 0-4 years. RESULTS: Half of the parents (48.9 %) gave their child sufficient vitamin D supplementation. Giving the supplement at a fixed time, a positive intention and habit were significantly associated with actual behaviour. The higher age of the child, first-born status, a fixed time for taking vitamin supplementation, descriptive norm and moral obligation were significantly associated with intention. CONCLUSIONS: These results indicate that because many parents do not give their children adequate vitamin D supplementation, the promotion of supplementation during the first years of life is a necessity. Effective yet simple strategies should be developed, focused on improving moral obligation, descriptive norms and habit formation

Structural asymmetries of the human cerebellum in relation to cerebral cortical asymmetries and handedness

Contains fulltext : 175106.pdf (publisher's version ) (Open Access)There is evidence that the human cerebellum is involved not only in motor control but also in other cognitive functions. Several studies have shown that language-related activation is lateralized toward the right cerebellar hemisphere in most people, in accordance with leftward cerebral cortical lateralization for language and a general contralaterality of cerebral-cerebellar activations. In terms of behavior, hand use elicits asymmetrical activation in the cerebellum, while hand preference is weakly associated with language lateralization. However, it is not known how, or whether, these functional relations are reflected in anatomy. We investigated volumetric gray matter asymmetries of cerebellar lobules in an MRI data set comprising 2226 subjects. We tested these cerebellar asymmetries for associations with handedness, and for correlations with cerebral cortical anatomical asymmetries of regions important for language or hand motor control, as defined by two different automated image analysis methods and brain atlases, and supplemented with extensive visual quality control. No significant associations of cerebellar asymmetries to handedness were found. Some significant associations of cerebellar lobular asymmetries to cerebral cortical asymmetries were found, but none of these correlations were greater than 0.14, and they were mostly method-/atlas-dependent. On the basis of this large and highly powered study, we conclude that there is no overt structural manifestation of cerebellar functional lateralization and connectivity, in respect of hand motor control or language laterality

Behavioral consequences of aberrant alpha lateralization in Attention-Deficit/Hyperactivity Disorder

Contains fulltext : 128510.pdf (publisher's version ) (Closed access