Neurocognitive and cerebellar function in ADHD, autism and spinocerebellar ataxia

Examining for Associations between Motor Disturbances and ADHD Status in Young Adults

OBJECTIVE

Some studies show an association between ADHD and impaired balance/gait in children. However, it remains largely unexplored whether such an association exists in adults. We explore that association in this study.

METHOD

This cross-sectional study included 45 adults aged 17 to 21 (25 with, and 20 without ADHD), most obtained from a longitudinal cohort study beginning in childhood. We measured balance/gait using objective measures from inertial sensors during the Instrumented Stand and Walk Test. Demographics and severity of ADHD symptoms were measured via questionnaires.

RESULTS

Young adults with ADHD showed a tendency toward worse balance and impaired gait in a dual-task activity than adults without ADHD.

CONCLUSION

These findings suggest balance and gait impairments are associated with ADHD in young adults. Balance/gait measures may hold promise as markers for persistent neurodevelopmental disorders, and the novel task used here may hold promise for measuring these impairments in adults with ADHD.

Sensorimotor functions, visuospatial perception and visuospatial abilities in adult attention deficit hyperactivity disorder and autism spectrum disorder

OBJECTIVE

The aim of this study was to investigate sensorimotor functions that require cerebellar processing, and visuospatial perception and visuospatial abilities in adult patients with attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD).

METHOD

We included patients with unmedicated ADHD (n = 52), medicated ADHD (n = 39), ASD (n = 33), the combination of unmedicated ADHD and ASD (n = 31) and controls (n = 78). A multimodal set of neurocognitive tests and motor tasks were administrated to evaluate cognitive and motor skills.

RESULTS

All patient groups exhibited significantly worse performances than controls in sensorimotor functions, visuospatial perception, and visuospatial abilities. We observed significant associations between sensorimotor functions and visuospatial perception and visuospatial abilities. We conducted a regression analysis to evaluate the impact of potential confounders on neurocognitive outcomes. The results indicated that age, level of education, and insomnia, but not anxiety or depression, affected the performance on some tests.

CONCLUSIONS

Our results reveal deficits in sensorimotor functions, visuospatial perception, and visuospatial abilities in patients with neuropsychiatric disorders. Clear deficits emerged, despite the majority of patients showing a mild degree of severity index of ADHD/ASD across all groups (61-84%). The results are consistent with the idea that these disorders are linked to cerebellar deficits. Our results suggest that these objective tests have the potential to enhance clinical evaluations.

New Perspectives on Non-Invasive Cerebellar Stimulation for Social and Affective Functions in Children and Adolescents

Cerebellar dysfunction affects socio-affective abilities beyond motor control. Recent studies suggest that non-invasive cerebellar neurostimulation can modulate social cognition networks, offering potential therapeutic benefits for children with autism, ADHD, and mood disorders. However, its application in pediatrics remains largely unexplored. This review summarizes emerging pediatric research on cerebellar transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). We discuss their mechanisms, potential benefits, and safety considerations, highlighting preliminary findings that suggest feasibility and effectiveness. Ethical concerns and technical challenges related to pediatric neuroanatomy and stimulation parameters are also addressed. While early results are promising, further clinical trials and neurophysiological studies are essential to optimize protocols and confirm long-term efficacy. Advancing our understanding of cerebellar involvement in socio-affective functions could lead to innovative rehabilitation strategies for neurodevelopmental disorders.

Psychiatric phenotype in neurodevelopmental myoclonus-dystonia is underpinned by abnormality of cerebellar modulation on the cerebral cortex

Psychiatric symptoms are common in neurodevelopmental movement disorders, including some types of dystonia. However, research has mainly focused on motor manifestations and underlying circuits. Myoclonus-dystonia is a rare and homogeneous neurodevelopmental condition serving as an illustrative paradigm of childhood-onset dystonias, associated with psychiatric symptoms. Here, we assessed the prevalence of psychiatric disorders and the severity of depressive symptoms in patients with myoclonus-dystonia and healthy volunteers (HV). Using resting-state functional neuroimaging, we compared the effective connectivity within and among non-motor and motor brain networks between patients and HV. We further explored the hierarchical organization of these networks and examined the relationship between their connectivity and the depressive symptoms. Comparing 19 patients to 25 HV, we found a higher prevalence of anxiety disorders and more depressive symptoms in the patient group. Patients exhibited abnormal modulation of the cerebellum on the cerebral cortex in the sensorimotor, dorsal attention, salience, and default mode networks. Moreover, the salience network activity was directed by the cerebellum in patients and was related to depressive symptoms. Altogether, our findings highlight the role of the cerebellar drive on both motor and non-motor cortical areas in this disorder, suggesting cerebellar involvement in the complex phenotype of such neurodevelopmental movement disorders.

Alcohol Toxicity in the Developing Cerebellum

The impact of ethanol on the fetus is a significant concern as an estimated 2-5% of live births may be affected by prenatal alcohol exposure. This exposure can lead to various functional and structural abnormalities in the cerebral cortex, basal ganglia, diencephalon, and cerebellum, resulting in region-specific symptoms. The deficits relate to the motor and cognitive domains, affecting, in particular, general intelligence, attention, executive functions, language, memory, visual perception, and social skills-collectively called the fetal alcohol spectrum disorder (FASD). Recent studies suggest that damage to the developing cerebellum (in form of alcohol exposure) can impair the cortical targets of the cerebello-thalamo-cortical tract. This malfunction in the cerebello-cerebral loop optimization may be due to disruptions in the formation of the foundational elements of the internal model within the developing cerebellum. Alcohol exposure targets multiple nodes in the reciprocal loops between the cerebellum and cerebral cortex. Here, we examine the possibility that prenatal alcohol exposure damages the developing cerebellum and disrupts the connectivity within the cerebello-cerebral neuronal circuits, exacerbating FASD-related cortical dysfunctions. We propose that malfunctions between cerebellar internal model (critically involved in predictions) and cerebral regions contribute to the deficits observed in FASD. Given the major role of the cerebellum in motor, cognitive, and affective functions, we suggest that therapies should target these malfunctions to mitigate the burden of FASD. We discuss the concept of therapies oriented towards malfunctioning cerebello-cerebral loops (TOMCCLs), emphasizing anti-inflammatory strategies and treatments aimed at modulating cerebellar myelination to restore optimal and predictive cerebello-cerebral functions.

Cerebellar network alterations in adult attention-deficit/hyperactivity disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition that often persists into adulthood. Underlying alterations in brain connectivity have been identified but some relevant connections, such as the middle, superior, and inferior cerebellar peduncles (MCP, SCP, and ICP, respectively), have remained largely unexplored; thus, we sought to investigate whether the cerebellar peduncles contribute to ADHD pathophysiology among adults.

METHODS

We applied diffusion-weighted spherical deconvolution tractography to dissect the cerebellar peduncles of male adults with ADHD (including those who did or did not respond to methylphenidate, based on at least 30% symptom improvement at 2 months) and controls. We investigated differences in tract metrics between controls and the whole ADHD sample and between controls and treatment-response groups using sensitivity analyses. Finally, we analyzed the association between the tract metrics and cliniconeuropsychological profiles.

RESULTS

We included 60 participants with ADHD (including 42 treatment responders and 18 nonresponders) and 20 control participants. In the whole ADHD sample, MCP fractional anisotropy (FA; t 78 = 3.24, p = 0.002) and hindrance modulated orientational anisotropy (HMOA; t 78 = 3.01, p = 0.004) were reduced, and radial diffusivity (RD) in the right ICP was increased (t 78 = -2.84, p = 0.006), compared with controls. Although case-control differences in MCP FA and HMOA, which reflect white-matter microstructural organization, were driven by both treatment response groups, only responders significantly differed from controls in right ICP RD, which relates to myelination (t 60 = 3.14, p = 0.003). Hindrance modulated orientational anisotropy of the MCP was significantly positively associated with hyperactivity measures.

LIMITATIONS

This study included only male adults with ADHD. Further research needs to investigate potential sex- and development-related differences.

CONCLUSION

These results support the role of the cerebellar networks, especially of the MCP, in adult ADHD pathophysiology and should encourage further investigation.

CLINICAL TRIAL REGISTRATION

NCT03709940.

Amyloid-induced neurodegeneration: A comprehensive review through aggregomics perception of proteins in health and pathology

Amyloidosis of protein caused by fibrillation and aggregation are some of the most exciting new edges not only in protein sciences but also in molecular medicines. The present review discusses recent advancements in the field of neurodegenerative diseases and therapeutic applications with ongoing clinical trials, featuring new areas of protein misfolding resulting in aggregation. The endogenous accretion of protein fibrils having fibrillar morphology symbolizes the beginning of neuro-disorders. Prognostic amyloidosis is prominent in numerous degenerative infections such as Alzheimer's and Parkinson's disease, Amyotrophic lateral sclerosis (ALS), etc. However, the molecular basis determining the intracellular or extracellular evidence of aggregates, playing a significant role as a causative factor in neurodegeneration is still unclear. Structural conversions and protein self-assembly resulting in the formation of amyloid oligomers and fibrils are important events in the pathophysiology of the disease. This comprehensive review sheds light on the evolving landscape of potential treatment modalities, highlighting the ongoing clinical trials and the potential socio-economic impact of novel therapeutic interventions in the realm of neurodegenerative diseases. Furthermore, many drugs are undergoing different levels of clinical trials that would certainly help in treating these disorders and will surely improve the socio-impact of human life.

Age-Related Dysfunction in Balance: A Comprehensive Review of Causes, Consequences, and Interventions

This review delves into the multifaceted aspects of age-related balance changes, highlighting their prevalence, underlying causes, and the impact they have on the elderly population. Central to this discussion is the exploration of various physiological changes that occur with aging, such as alterations in the vestibular, visual, proprioceptive systems, and musculoskeletal degeneration. We examine the role of neurological disorders, cognitive decline, and medication side effects in exacerbating balance issues. The review underscores the significance of early detection and effective intervention strategies in mitigating the risks associated with balance problems, such as falls and reduced mobility. It discusses the effectiveness of diverse intervention strategies, including exercise programs, rehabilitation techniques, and technological advancements like virtual reality, wearable devices, and telemedicine. Additionally, the review stresses the importance of a holistic approach in managing balance disorders, encompassing medication review, addressing comorbidities, and environmental modifications. The paper also presents future research directions, emphasizing the need for a deeper understanding of the complex mechanisms underlying balance changes with aging and the potential of emerging technologies and interdisciplinary approaches in enhancing assessment and intervention methods. This comprehensive review aims to provide valuable insights for healthcare providers, researchers, and policymakers in developing targeted strategies to improve the quality of life and ensure the well-being of the aging population.

Arousal dysregulation and executive dysfunction in attention deficit hyperactivity disorder (ADHD)

Attention deficit/hyperactivity disorder (ADHD) is a heterogeneous neurodevelopmental condition, that continues to have an elusive etiological background. A number of extant models and theories have historically intended to explain the many factors contributing to ADHD behaviors. One of the most accepted hypotheses has been the executive dysfunction theory associating reduction in executive control to abnormalities in structure and operational dysfunction of dopaminergic signaling networks. Nevertheless, executive functions are not always impaired in ADHD, and the literature describes other symptoms commonly reported suggesting individuals with ADHD would appear to suffer from a more general deficit. Another existing line of research, that has gained much attention recently, establishes that ADHD would have dysregulated states of brain arousal that would account for its commonly observed cognitive deficits and behavioral symptoms, described as the state regulation theory, which has now included measures of autonomic function. This article describes some important aspects that compose and challenge these two most influential theoretical constructs, executive dysfunction and state-regulation, based on their empirical evidence, implying the need to reevaluate the norms used to classify individuals and establish ADHD diagnosis. Large number of controversial results continue to exist within the study of ADHD biological and/or performance markers, possibly due to such heterogeneity and variability within the same diagnosis. The need to resolve these issues and establish newly revised diagnostic criteria for ADHD is critical, as therapeutic success depends on having accurately identified underlying neurophysiological factors in order to appropriately address them in treatment.

The ability to maintain rhythm is predictive of ADHD diagnosis and profile

Attention deficit hyperactivity disorder (ADHD) is the most prevalent neuropsychiatric disorder in the world. Currently, the diagnosis is based mainly on interviews, resulting in uncertainties in the clinical assessment. While some neuropsychological tests are used, their specificity and selectivity are low, and more reliable biomarkers are desirable. Previous research indicates that ADHD is associated with morphological changes in the cerebellum, which is essential for motor ability and timing. Here, we compared 29 children diagnosed with ADHD to 96 age-matched controls on prism adaptation, eyeblink conditioning, and timed motor performance in a finger tapping task. Prism adaptation and timing precision in the finger tapping task, but not performance on eyeblink conditioning, differed between the ADHD and control groups, as well as between children with and without Deficits in Attention, Motor control, and Perception (DAMP) - a more severe form of ADHD. The results suggest finger tapping can be used as a cheap, objective, and unbiased biomarker to complement current diagnostic procedures.