ADHD And Your Brain
ADHD is just three neurotransmitters.
While there are many ways to manage your ADHD, one of the first things you should do is to try to understand what ADHD is. Understand the neurobiology of ADHD, how it affects your brain, body and your emotions.
Here are some links to articles and websites explaining the neurobiology of ADHD as well as general information on how your brain works.
There is also more detailed scientific info on my page on the Clinical Evidence of the Existence of ADHD as a Real Condition, created for the people who believe in flat earth theories and other fantasies, or the ADDers who are willing to educate them.
Where is the Caudate Nucleus? Where is the Cingulate Cortex? What does it do? Find out here, can annotate it, zoom in and take screenshots too.
From BrainFacts.org Covers:
- Your Complex Brain
- How Neurons Communicate
- How Your Brain Processes Information
- How Experience Shapes Your Brain
- Reasoning, Planning & Solving Problems
- The Power of Language
- The Source of Curiosity
- How Research Benefits Human Health
Abnormal Brain Activation During Inhibition and Error Detection in Medication-Naive Adolescents With ADHD
American Journal of Psychiatry. By Katya Rubia , Ph.D., Anna B. Smith , Ph.D., Michael J. Brammer , Ph.D., Brian Toone , Ph.D., and Eric Taylor , M.D., Ph.D.
“The aim of this study was to investigate whether medication-naive adolescents with ADHD would still show abnormal brain activation in prefrontal brain regions during motor response inhibition in a task designed to control for intergroup performance discrepancies
RESULTS: Medication-naive adolescents with ADHD showed significantly reduced brain activation in the right inferior prefrontal cortex during successful motor response inhibition and in the precuneus and posterior cingulate gyrus during inhibition failure, both of which correlated with behavioral scores of ADHD.
CONCLUSIONS: The study shows that abnormal brain activation during inhibitory challenge in ADHD is specific to the disorder, since it persists when medication history and performance discrepancies are excluded…
Single photon emission tomography studies have found reduced cerebral blood flow at rest in the inferior prefrontal and temporal lobes. PET studies of adult ADHD patients found reduced activation in left-hemispheric temporal lobes and insula during working memory and decision making.
It thus appears that the insula, inferior prefrontal, and anterior temporal lobes are brain regions of structural and functional abnormality in ADHD.
Proceedings of The National Academy of Sciences of the USA.
“We found maturation to progress in a similar manner regionally in both children with and without ADHD, with primary sensory areas attaining peak cortical thickness before polymodal, high-order association areas.
However, there was a marked delay in ADHD in attaining peak thickness throughout most of the cerebrum: the median age by which 50% of the cortical points attained peak thickness for this group was 10.5 years (SE 0.01), which was significantly later than the median age of 7.5 years (SE 0.02) for typically developing controls (log rank test χ(1)2 = 5,609, P < 1.0 × 10−20).
The delay was most prominent in prefrontal regions important for control of cognitive processes including attention and motor planning. Neuroanatomic documentation of a delay in regional cortical maturation in ADHD has not been previously reported.”
Supporting info and movies here.
Attention and Executive Systems Abnormalities In Adults With Childhood ADHD: A DT-MRI Study of Connections.
Cerebral Cortex. “In this study of adults with childhood ADHD, we hypothesized that fiber pathways subserving attention and executive functions (EFs) would be altered.
To this end, the cingulum bundle (CB) and superior longitudinal fascicle II (SLF II) were investigated in vivo in 12 adults with childhood ADHD and 17 demographically comparable unaffected controls using DT-MRI.
Relative to controls, the fractional anisotropy (FA) values were significantly smaller in both regions of interest in the right hemisphere, in contrast to a control region (the fornix), indicating an alteration of anatomical connections within the attention and EF cerebral systems in adults with childhood ADHD.
The demonstration of FA abnormalities in the CB and SLF II in adults with childhood ADHD provides further support for persistent structural abnormalities into adulthood.”
The Brain Anatomy Of Attention-Deficit/Hyperactivity Disorder In Young Adults – A Magnetic Resonance Imaging Study
PLOS 1. By Jean-G. Gehricke , Frithjof Kruggel, Tanyaporn Thampipop, Sharina Dyan Alejo, Erik Tatos, James Fallon, L. Tugan Muftuler.
Voxel-wise linear regression models were used to examine structural and diffusion-weighted MRI data in 72 participants (31 young adults with ADHD and 41 controls without ADHD) in relation to diagnosis and the number of self-reported child and adult symptoms.
Findings revealed significant associations between ADHD diagnosis and widespread changes to the maturation of white matter fiber bundles and gray matter density in the brain, such as structural shape changes (incomplete maturation) of the middle and superior temporal gyrus, and fronto-basal portions of both frontal lobes. ADHD symptoms in childhood showed the strongest association with brain macro- and microstructural abnormalities. At the brain circuitry level, the superior longitudinal fasciculus (SLF) and cortico-limbic areas are dysfunctional in individuals with ADHD. The morphometric findings predicted an ADHD diagnosis correctly up to 83% of all cases.
An adult ADHD diagnosis and in particular childhood symptoms are associated with widespread micro- and macrostructural changes. The SLF and cortico-limbic findings suggest complex audio-visual, motivational, and emotional dysfunctions associated with ADHD in young adults. The sensitivity of the morphometric findings in predicting an ADHD diagnosis was sufficient, which indicates that MRI-based assessments are a promising strategy for the development of a biomarker.
“This is a free 180 page primer on the brain and nervous system, published by the Society for Neuroscience. Brain Facts is a valuable resource for secondary school teachers and students who participate in the Brain Bee.
The book covers functions of the brain, diseases and disorders, research methods, and neuroethics.
New additions to the book include eight fundamental core concepts of neuroscience, an enhanced anatomy section with references to the new 3D brain model on the companion website, and more than 150 glossary terms to provide further value for educators.
“The book is very complementary to the many interactive resources currently available on BrainFacts.org, including the 3D model of the brain,”
Psychiatric Times By Amir Raz, Ph.D.
“Neuroimaging assays have most consistently implicated abnormalities of the dorsal prefrontal cortex and basal ganglia in ADHD.
Reduced metabolic rates have been reported in the left sensorimotor area in children with ADHD and in the premotor and superior prefrontal cortices of adults with ADHD.
Positron emission tomography data from 10 adolescents with ADHD found reduced metabolic rates versus healthy controls in, among other regions, the left anterior frontal area, showing negative correlation with numerous symptom severity measure.
Smaller volumes of the right prefrontal cortex have been reported in children with ADHD compared with healthy controls.
Magnetic resonance imaging data demonstrated smaller right globus pallidus nuclei in boys with ADHD relative to a control group.
Individuals with ADHD had significantly smaller brain volumes in all regions, even after adjustment for significant covariates. This global difference was reflected in smaller total cerebral volumes and in significantly smaller cerebellar volumes.
Unmedicated children with ADHD also exhibited smaller total white matter volumes compared with controls and with medicated children with ADHD.
fMRI studies have reported abnormal activation of the striatum, prefrontal cortex and anterior cingulate cortex in ADHD.
Whereas control participants activated the anterior cingulate cortex, participants with ADHD seemed to rely on the anterior insula–a brain region typically associated with responses in more routine tasks not involving conflict.”
Psychiatric News. “New high-resolution, three-dimensional maps of the brains of children with attention-deficit hyperactivity disorder indicate significant and specific anatomical differences within areas of the brain thought to control attentional and inhibitory control systems, compared with brain scans of children without ADHD.
The images are thought to be the most advanced to date to reveal the anatomical basis of the disorder. Includes two 3d scan photos.”
Also show how positive emotions can benefit your immune system.
New England Journal Of Medicine. By Alan J. Zametkin, M.D., Thomas E. Nordahl, Ph.D., M.D., Michael Gross, M.D., A. Catherine King, William E. Semple, Ph.D., Judith Rumsey, Ph.D., Susan Hamburger, M.S., and Robert M. Cohen, Ph.D., M.D.
“We investigated the hypothesis that cerebral glucose metabolism might differ between normal adults (controls) and adults with histories of hyperactivity in childhood who continued to have symptoms. Each patient was also the biologic parent of a hyperactive child. None of the adults had ever been treated with stimulant medication.
To measure cerebral glucose metabolism, we administered 148 to 185 MBq (4 to 5 mCi) of [18F]fluoro-2-deoxy-D-glucose intravenously to 50 normal adults and 25 hyperactive adults while they performed an auditory-attention task. Images were obtained for 30 minutes with a Scanditronix positron-emission tomograph with a resolution of 5 to 6 mm.
Glucose metabolism, both global and regional, was reduced in adults who had been hyperactive since childhood. The largest reductions were in the premotor cortex and the superior prefrontal cortex — areas earlier shown to be involved in the control of attention and motor activity.
As assessed by PET scanning, global cerebral glucose metabolism was 8.1 percent lower in the hyperactive patients than in the controls.
Absolute regional glucose-metabolism rates differed significantly between the two groups (P<0.05, 70 to 73 df, by two-tailed t-test) for 30 of the 60 specific brain regions we studied. In all 30, including both cortical and subcortical regions, metabolism in the patients was depressed.
When the values for the individual regions of interest were normalized (divided by the global glucose values, as described in Methods), four regions, primarily in the premotor and somatosensory cortex, had significantly lower metabolism in the patients than in the controls
EFFECTS OF SEX
Global glucose metabolism was 1.9 percent higher in the brains of the women with hyperactivity than in those of the men with hyperactivity.
Thus, the absolute differences that we observed in cerebral glucose metabolism were widespread, unidirectional, and bilateral. The areas with the greatest depression in glucose metabolism (as judged by the levels of significance of the differences between the groups) include but are not limited to the premotor and superior prefrontal regions.
In summary, we noted differences in cerebral glucose metabolism between hyperactive adults and normal adult controls, specifically in regions of the brain that have been postulated to be important in the control of preparation for motor activity, motor activity itself, inhibition of inappropriate response, and attention.”
Clinical Implications of the Perception of Time in Attention Deficit Hyperactivity Disorder (ADHD): A Review
Medical Science Monitor. By Radek Ptacek, Simon Weissenberger, Ellen Braaten, Martina Klicperova-Baker, Michal Goetz, Jiri Raboch, Martina Vnukova,and George B. Stefano.
“This review summarizes recent research on the perception of time in ADHD and proposes that this symptom is a possible diagnostic characteristic.
Controlled studies on time perception have compared individuals with ADHD with typically developing controls (TDCs) and have used methods that include the Zimbardo Time Perspective Inventory (ZTPI).
Practical approaches to time perception and its evaluation have shown that individuals with ADHD have difficulties in time estimation and discrimination activities as well as having the feeling that time is passing by without them being able to complete tasks accurately and well.
Although ADHD has been associated with neurologic abnormalities in the mesolimbic and dopaminergic systems, recent studies have found that when individuals with ADHD are treated medically, their perception of time tends to normalize.
The relationship between ADHD and the perception of time requires greater attention.”
Cerebral Cortex 2007 17(6):1364-1375. “ADHD has been associated with structural alterations in brain networks influencing cognitive and motor behaviors. Volumetric studies in children identify abnormalities in cortical, striatal, callosal, and cerebellar regions.
We carried out a structural magnetic resonance imaging study of cortical thickness in the same sample of adults with ADHD.
Compared with healthy adults, adults with ADHD showed selective thinning of cerebral cortex in the networks that subserve attention and EF.
In the present study, we found significant cortical thinning in ADHD in a distinct cortical network supporting attention especially in the right hemisphere involving the inferior parietal lobule, the dorsolateral prefrontal, and the anterior cingulate cortices.
This is the first documentation that ADHD in adults is associated with thinner cortex in the cortical networks that modulate attention and EF.”
European Archives of Psychiatry and Clinical Neuroscience. “In this study, we provide meaningful electrophysiological evidence of ED in adult patients with ADHD (n = 39) compared to healthy controls (n = 40) by exploring the electrophysiological correlates of the emotion regulation strategies reappraisal, distraction, and expressive suppression.
Event-related potentials (ERPs) were recorded during passive viewing of neutral and negative images, as well as during emotion regulation.
The patients with ADHD exhibited increased frontal late positive potential (LPP) amplitudes during passive viewing of the aversive images and during emotion regulation.
Compared with the healthy controls, a subgroup of medication-naïve patients with ADHD (n = 25) also exhibited larger centroparietal LPP amplitudes and provided more negative ratings of the aversive and neutral images.
Both the frontal and centroparietal LPP amplitudes were associated with ADHD symptom severity.
However, no significant deficit in LPP modulation during emotion regulation was found.
These findings strongly support the clinical observation of increased emotional responsivity toward negative stimuli and difficulty during the implementation of emotion regulation strategies and thus encourage the implementation of emotion regulation modules in the treatment of adult patients with ADHD.”
Brain Research. “Twenty-two right-handed, non-medicated children (12 ADHD, 10 controls) ages 8–12 years completed a fluid reasoning task during which fMRI data were collected.
Fluid reasoning, also known as analogical or relational reasoning, is the ability to manipulate representations among stimuli in order to reason, plan, and problem solve using attentional, working memory, and cognitive perceptual skills.
It involves relational integration, inhibitory control, and resolution of interference and is considered a core component of fluid intelligence.
In fact, fluid reasoning appears critical for all tasks identified with executive functioning and may comprise an executive function resource that influences self-regulation of cognition and behavior.
The primary comparison of interest was activation during the fluid reasoning compared to the control condition.
Behavioral data showed that children with ADHD tended to be less accurate with faster reaction times in the fluid reasoning condition compared to controls, and were significantly less accurate in the control condition.
Controls activated more than participants with ADHD in the right intraparietal sulcus and the left lateral cerebellum in the fluid reasoning condition.
Results showed hypoactivation in ADHD in regions critical for fluid reasoning. These results add to the literature suggesting a role for parietal and cerebellar regions in cognition and ADHD.
Deficits in fluid reasoning may be related to cognition and behavior deficits in ADHD.
Results showed hypoactivation in ADHD in regions critical for fluid reasoning,
Findings suggest particular deficits in parietal/cerebellar regions.”
The Institute of HeartMath is an innovative nonprofit research and education organization. Their primary mission is to facilitate people in finding the balance between mind and heart in life’s decisions.
Annals of Clinical Psychiatry. Daniel G. Amen, M.D and Blake D. Carmichael, BA
“Brain SPECT (single-photon emission computed tomography) imaging is a nuclear medicine study which may offer the most widely available and widely applicable measure of neuronal behavior (1). SPECT measures cerebral blood flow and, indirectly, brain metabolism
Children and adolescents with ADHD were evaluated with high-resolution brain SPECT imaging to determine if there were similarities between reported PET and QEEG findings.
Fifty-four children and adolescents with ADHD by DSM-III-R and Conners Rating Scale criteria were evaluated. A non-ADHD control group was also studied with SPECT.
Two brain SPECT studies were done on each group, a resting study and an intellectual stress study done while participants were doing a concentration task.
Sixty-five percent of the ADHD group revealed decreased perfusion in the prefrontal cortex with intellectual stress, compared to only 5% of the control group.
These are findings consistent with PET and QEEG findings.
Of the ADHD group who did not show decreased perfusion, two-thirds had markedly decreased activity in the prefrontal cortices at rest.”
By Sue Gerhardt, psychoanalytic psychotherapist and author of Why Love Matters: How Affection Shapes a Baby’s Brain.
In order to develop a ‘social brain’, babies need loving one-to-one care. The attention that we receive as babies impacts on our brain structures.
If we find ourselves cared for by people who love us, and who are highly sensitive to our unique personalities, the pleasure of those relationships will help to trigger the development of the “social brain”.
In the simplest terms, the pre-frontal cortex (and in particular its orbitofrontal area) plays a major role in managing our emotional lives: it picks up on social cues, the non-verbal messages that other people transmit, it enables us to empathise, as well as playing an important part in restraining our primitive emotional impulses.
Surprising as it may seem, we are not born with these capacities:this part of the brain develops almost entirely post-natally. Nor is it just a matter of waiting for your baby to develop an orbitofrontal cortex so it can begin to relate well to others.There is nothing automatic about it.
Instead, the kind of brain that each baby develops is the brain that comes out of his or her experiences with other people. Love facilitates a massive burst of connections in this part of the brain between six and 12 months. Neglect at this time can greatly reduce the development of the pre-frontal cortex.
Inhibitory Control of Memory Retrieval and Motor Processing Associated with the Right Lateral Prefrontal Cortex: Evidence from Deficits in Individuals with ADHD
Neuropsychologia. “The current study examined whether inhibitory difficulties in ADHD extend to inhibitory control over memory retrieval.
During fMRI 16 individuals with ADHD and 16 controls performed the Think/No-Think (TNT) task. Behaviorally, the Stop Signal Reaction Time task (SSRT) was used to assess inhibitory control over motor responses.
To link both of these measures to behavior, the severity of inattentive and hyperactive symptomatology was also assessed.
Behaviorally, ADHD individuals had specific difficulty in inhibiting, but not in elaborating/increasing memory retrieval, which was correlated with symptom severity and longer SSRT.
Additionally, ADHD individuals showed reduced activity in rLPFC during the TNT, as compared to control individuals.
Moreover, unlike controls, in whom the correlation between activity of the rMFG and hippocampus predicts inhibitory success, no such correlation was observed for ADHD individuals.
Moreover, decreased activity in rIFG in individuals with ADHD predicted a decrease in the ability to inhibit motor responses.
These results suggest that inhibitory functions of rLPFC include control over both memory and motoric processes. They also suggest that inhibitory deficits in individuals with ADHD extend to the memory domain.”
PLOS.One. By New-Fei Ho, Joanna S. X. Chong, Hui Li Koh, Eleni Koukouna, Tih-Shih Lee, Daniel Fung, Choon Guan Lim, Juan Zhou.
“In this study, we use resting-state functional magnetic resonance imaging to test the hypothesis of diminished functional integration within the affective/limbic network (which includes the amygdala, hippocampus, subgenual cingulate cortex, orbitofrontal cortex and nucleus accumbens) of children with ADHD, which is associated with their behavioral measures of emotional control deficits.
Resting state-fMRI data were obtained from 12 healthy control subjects and 15 children with ADHD, all who had a minimum one-month washout period for medications and supplements.
Children with ADHD demonstrated less integrated affective network, evidenced by increased bilateral amygdalar and decreased left orbitofrontal connectivity within the affective network compared to healthy controls.
The hyper-connectivity at the left amygdalar within the affective network was associated with increased aggressiveness and conduct problems, as well as decline in functioning in children with ADHD. Similar findings in affective network dysconnectivity were replicated in a subset of children with ADHD three months later.
Our findings of divergent changes in amygdala and orbitofrontal intrinsic connectivity support the hypothesis of an impaired functional integration within the affective network in childhood ADHD.
Larger prospective studies of the intrinsic affective network in ADHD are required, which may provide further insight on the biological mechanisms of emotional control deficits observed in ADHD.”
Multimodal Mapping Of The Brain’s Functional Connectivity And The Adult Outcome Of Attention Deficit Hyperactivity Disorder
Proceedings of the National Academy of Sciences of the United States of America. By Gustavo Sudre, Eszter Szekely, Wendy Sharp, Steven Kasparek, and Philip Shawa.
We map the brain’s functional architecture in 205 young adults followed clinically since childhood. We find clinically significant inattention persisting from childhood has a disruptive effect on the functional connections within and between the brain’s major networks.
These disruptions are similar whether defined through direct observation of neuronal activity or measures of hemodynamic change.
Findings revealed significant associations between ADHD diagnosis and widespread changes to the maturation of white matter fiber bundles and gray matter density in the brain, such as structural shape changes (incomplete maturation) of the middle and superior temporal gyrus, and fronto-basal portions of both frontal lobes.
ADHD symptoms in childhood showed the strongest association with brain macro- and microstructural abnormalities. At the brain circuitry level, the superior longitudinal fasciculus (SLF) and cortico-limbic areas are dysfunctional in individuals with ADHD.
Very comprehensive detailed video on the neurochemistry and neurobiology of ADHD by Dr. Anthony L. Rostain. He’s a “Professor of Psychiatry and Pediatrics at the University of Pennsylvania Perelman School of Medicine, Philadelphia, USA. His clinical focus is “lifespan neurodevelopmental psychiatry.”
He treats patients at The Children’s Hospital of Philadelphia, where he is Co-Director of the Pediatric Neurodevelopmental Psychiatry Service, and at Penn Medicine / Behavioral Health where he is Medical Director of the Adult Development Disorders Unit which includes the Adult ADHD Treatment and Research Program.”
Dr. Rostain’s research interests focus on improving clinical outcomes for patients across the lifespan with neurodevelopmental disorders, and on creating effective service systems for these patients and their families.
He has co-authored two books on adult ADHD, entitled The Adult ADHD Tool Kit: Using CBT to Facilitate Coping Inside and Out, and Cognitive-Behavioral Therapy for Adult ADHD: An Integrative Psychosocial and Medical Approach.
Created for all students and teachers who would like to learn about the nervous system. Adults can learn a lot from this site too. Click the links on the left.
Neural Network Topology In ADHD; Evidence For Maturational Delay And Default-Mode Network Alterations
Attention-deficit/hyperactivity disorder (ADHD) has been associated with widespread brain abnormalities in white and grey matter, affecting not only local, but global functional networks as well. In this study, we explored these functional networks using source-reconstructed electroencephalography in ADHD and typically developing (TD) children. We expected evidence for maturational delay, with underlying abnormalities in the default mode network.
Electroencephalograms were recorded in ADHD (n=42) and TD (n=43) during rest, and functional connectivity (phase lag index) and graph (minimum spanning tree) parameters were derived. Dependent variables were global and local network metrics in theta, alpha and beta bands.
We found evidence for a more centralized functional network in ADHD compared to TD children, with decreased diameter in the alpha band (ηp2=0.06) and increased leaf fraction (ηp2=0.11 and 0.08) in the alpha and beta bands, with underlying abnormalities in hub regions of the brain, including default mode network.
The finding of a more centralized network is in line with maturational delay models of ADHD and should be replicated in longitudinal designs.
This study contributes to the literature by combining high temporal and spatial resolution to construct EEG network topology, and associates maturational-delay and default-mode interference hypotheses of ADHD.”
Pharmaco-Meg Evidence For Attention Related Hyper-Connectivity Between Auditory And Prefrontal Cortices In ADHD
Psychiatry Research: Neuroimaging. “Both hyper- and hypo-activation in the dorsolateral prefrontal cortex, DLPFC, has been reported in patients with attention-deficit hyperactivity disorder (ADHD) during many different cognitive tasks, but the network-level effects of such aberrant activity remain largely unknown.
Using magnetoencephalography (MEG), we examined functional connectivity between regions of the DLPFC and the modality-specific auditory cortices during an auditory attention task in medicated and un-medicated adults with ADHD, and those without ADHD.
Participants completed an attention task in two separate sessions (medicated/un-medicated), and each session consisted of two blocks (attend and no-attend). All MEG data were coregistered to structural MRI, corrected for head motion, and projected into source space.
Subsequently, we computed the phase coherence (i.e., functional connectivity) between DLPFC regions and the auditory cortices.
We found that un-medicated adults with ADHD exhibited greater phase coherence in the beta (14–30Hz) and gamma frequency (30–56 Hz) range in attend and no-attend conditions compared to controls.
Stimulant medication attenuated these differences, but did not fully eliminate them. These results suggest that aberrant bottom-up processing may engulf executive resources in ADHD.”
From Medscape. Free registration required. “Studies using positron emission tomography (PET) and other approaches suggest new details about the underlying biology of ADHD. Released here at the 50th annual meeting of the Society of Nuclear Medicine.” 3 different studies mentioned.
Regional Gray Matter Volume Differences Between Adolescents With ADHD and Typically Developing Controls: Further Evidence for Anterior Cingulate Involvement.
Journal of Attention Disorders.
Voxel-based morphometry (VBM) using the DARTEL approach was performed to assess regional gray matter (GM) volumes. Additionally, individual performance on tests of attention was recorded to correlate ADHD related cognitive impairments with regional gray matter abnormalities.
We found significantly smaller GM volume in subjects with ADHD compared to their matched controls within the anterior cingulate cortex (ACC), the occipital cortex, bilateral hippocampus/amygdala and in widespread cerebellar regions. Further, reductions of the ACC gray matter volume were found to correlate with scores of selective inattention.
These findings underline that structural alterations in a widespread cortico-subcortical network seem to underlie the observable attention problems in patients with ADHD.”
Review Of Fronto-Striatal And Fronto-Cortical Brain Abnormalities In Children And Adults With Attention Deficit Hyperactivity Disorder (ADHD) And New Evidence For Dysfunction In Adults With Adhd During Motivation And Attention
Cortex. “In this paper we review the current structural and functional imaging evidence for abnormalities in children and adults with ADHD in fronto-striatal, fronto-parieto-temporal, fronto-cerebellar and fronto-limbic regions and networks.
While the imaging studies in children with ADHD are more numerous and consistent, an increasing number of studies suggests that these structural and functional abnormalities in fronto-cortical and fronto-subcortical networks persist into adulthood, despite a relative symptomatic improvement in the adult form of the disorder.
We furthermore present new data that support the notion of a persistence of neurofunctional deficits in adults with ADHD during attention and motivation functions.
We show that a group of medication-naïve young adults with ADHD behaviours who were followed up 20 years from a childhood ADHD diagnosis show dysfunctions in lateral fronto-striato-parietal regions relative to controls during sustained attention, as well as in ventromedial orbitofrontal regions during reward, suggesting dysfunctions in cognitive-attentional as well as motivational neural networks.
The lateral fronto-striatal deficit findings, furthermore, were strikingly similar to those we have previously observed in children with ADHD during the same task, reinforcing the notion of persistence of fronto-striatal dysfunctions in adult ADHD.
The ventromedial orbitofrontal deficits, however, were associated with comorbid conduct disorder (CD), highlighting the potential confound of comorbid antisocial conditions on paralimbic brain deficits in ADHD.
Our review supported by the new data therefore suggest that both adult and childhood ADHD are associated with brain abnormalities in fronto-cortical and fronto-subcortical systems that mediate the control of cognition and motivation.
The brain deficits in ADHD therefore appear to be multi-systemic and to persist throughout the lifespan.”
Right Parietal Dysfunction In Children With Attention Deficit Hyperactivity Disorder, Combined Type: A Functional MRI Study
Molecular Psychiatry. By A Vance, T J Silk, M Casey, N J Rinehart, J L Bradshaw, M A Bellgrove & R Cunnington
“Attention deficit hyperactivity disorder, combined type (ADHD-CT) is associated with spatial working memory deficits. These deficits are known to be subserved by dysfunction of neural circuits involving right prefrontal, striatal and parietal brain regions. This study determines whether decreased right prefrontal, striatal and parietal activation with a mental rotation task shown in adolescents with ADHD-CT is also evident in children with ADHD-CT.
Participants underwent functional magnetic resonance imaging while performing a mental rotation task that requires spatial working memory. The two groups did not differ in their accuracy or response times for the mental rotation task.
The ADHD-CT group showed significantly less activation in right parieto-occipital areas (cuneus and precuneus, BA 19), the right inferior parietal lobe (BA 40) and the right caudate nucleus. Our findings with a child cohort confirm previous reports of right striatal-parietal dysfunction in adolescents with ADHD-CT. This dysfunction suggests a widespread maturational deficit that may be developmental stage independent.
Spatial working memory is a crucial cognitive process that is impaired in ADHD. A recent meta-analysis highlights spatial working memory, more so than verbal working memory, as a key cognitive impairment in ADHD.
Using fMRI, we found reduced activation in regions of the inferior and superior parietal cortex and middle frontal areas in adolescents with ADHD-CT.3 In contrast, increased activation was observed in the superior and middle temporal regions that have been linked to the ventral visual stream for object recognition, possibly suggesting a more object-based approach to the mental rotation task.
Increased activation was also found in the ADHD-CT group in the posterior cingulate and medial superior prefrontal areas that are functionally linked in the motivational shifting of attentional focus.
Overall, children with ADHD-CT showed impaired activation in a widespread area of the right parietal lobe, including right inferior parietal cortex and the right parieto-occipital junction, while in the left parietal lobe significant activation was found for both ADHD-CT and control children.
These activation differences occurred despite a lack of behavioural performance difference on the mental rotation task, suggesting that activation differences are not simply due to poorer performance in the ADHD-CT group.
Rather, these activation differences may reflect a dysfunctional use of the same/and or a different strategy of the children with ADHD-CT use to complete the spatial working memory task, aside from the conscious willed approach taken by each child.
We therefore suggest that right parietal dysfunction in ADHD-CT is development-stage independent, observed both in adolescents and children, and contributes to known clinical and behavioural deficits such as impairments in the control of attention and spatial working memory.”
Journal of Abnormal Psychology. By Cepeda NJ, Cepeda ML, and Kramer AF.
“The main goal of the present set of studies was to examine the efficiency of executive control processes and, more specifically, the control processes involved in task set inhibition and preparation to perform a new task in ADHD & non-ADHD children.
This was accomplished by having ADHD children, both on and off medication, and non-ADHD children perform the task-switching paradigm, which involves the performance of two simple tasks.
In nonswitch trials, an individual task is performed repeatedly for a number of trials. In switch trials, subjects must rapidly and accurately switch from one task to the other, either in a predictable or unpredictable sequence.
Switch costs are calculated by subtracting performance on the nonswitch trials from performance on the switch trials. These costs are assumed to reflect the executive control processes required for the coordination of multiple tasks.
ADHD children showed substantially larger switch costs than non-ADHD children.
However, when on medication, the ADHD children’s switch performance was equivalent to control children.
In addition, medication was observed to improve the ADHD children’s ability to inhibit inappropriate responses.”
Very good description of the Neurology of ADD including photos. The site is a commercial website selling an ADD product called Attend, and I’m not recommending their product or all their content, but this page has some good information on it.
Timing Deficits In Attention-Deficit/Hyperactivity Disorder (ADHD): Evidence From Neurocognitive And Neuroimaging Studies
Neuropsychologia. “The present review provides a synthetic overview of the evidence for neurocognitive and neurofunctional deficits in ADHD in timing functions, and integrates this evidence with the cognitive neuroscience literature of the neural substrates of timing.
The review demonstrates that ADHD patients are consistently impaired in three major timing domains, in motor timing, perceptual timing and temporal foresight, comprising several timeframes spanning milliseconds, seconds, minutes and longer intervals up to years.
The most consistent impairments in ADHD are found in sensorimotor synchronisation, duration discrimination, reproduction and delay discounting.
These neurocognitive findings of timing deficits in ADHD are furthermore supported by functional neuroimaging studies that show dysfunctions in the key inferior fronto-striato-cerebellar and fronto-parietal networks that mediate the timing functions.
Although there is evidence that these timing functions are inter-correlated with other executive functions that are well established to be impaired in the disorder, in particular working memory, attention, and to a lesser degree inhibitory control, the key timing deficits appear to survive when these functions are controlled for, suggesting independent cognitive deficits in the temporal domain.
There is furthermore strong evidence for an association between timing deficits and behavioural measures of impulsiveness and inattention, suggesting that timing problems are key to the clinical behavioural profile of ADHD.
Emerging evidence shows that the most common treatment of ADHD with the dopamine agonist and psychostimulant Methylphenidate attenuates most timing deficits in ADHD and normalises the abnormally blunted recruitment of the underlying fronto-striato-cerebellar networks.
Timing function deficits in ADHD, therefore, next to executive function deficits, form an independent impairment domain, and should receive more attention in neuropsychological, neuroimaging, and pharmacological basic research as well as in translational research aimed to develop pharmacological or non-pharmacological treatment of abnormal timing behaviour and cognition in ADHD.”
By Dr P.V.F. Cosgrove Consultant Child and Adolescent psychiatrist. “MRI scans assessed the frontal circuitry in 18 ADHD boys in comparison to 18 matched controls.
They found that two anterior regions of the corpus callosum (the rostrum and the rostral body) were significantly smaller and concluded that this was evidence for frontal lobe dysfunction and abnormal development.
The callosal fibres in the rostral body relate to the premotor cortex, which is critical for “the suppression of relatively automatic responses to certain sensory stimuli”.
This is consistent with a defect in the person’s ability to inhibit responses, which is considered by Barkley to be the fundamental deficit in ADHD.”
Neurology. “Case-control study. Despite similar hemispheric volumes, ADHD subjects had smaller volumes of (1) left total caudate and caudate head (p <0.04), with reversed asymmetry (p < 0.03); (2) right anterior-superior (frontal) region en bloc (p < 0.03) arid white matter (p < 0.01); (3) bilateral anterior-inferior region en bloc (p <0.04); and (4) bilateral retrocallosal (parietal-occipital) region white matter (p < 0.03).
Possible structural correlates of ADHD response to stimulants were noted in an exploratory analysis, with the smallest and symmetric caudate, and smallest left anterior-superior cortex volumes found in the responders, but reversed caudate asymmetry and the smallest retrocallosal white matter volumes noted in the nonresponders.”
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