Patients with mutations of the Thyroid hormone beta-receptor show an ADHD-like phenotype for performance monitoring: an electrophysiological study

Altered brain functional connectivity in patients with resistance to thyroid hormone ß

To investigate changes in brain network organization and possible neurobehavioral similarities to attention-deficit hyperactivity disorder (ADHD), we measured changes in brain resting-state functional connectivity (rs-fMRI) and cognitive domains in patients with resistance to thyroid hormone β (RTHβ) and compared them with those in healthy control subjects. In this prospective case-control study, twenty-one participants with genetically confirmed RTHβ were matched with 21 healthy controls. The Adult ADHD Self-Report Scale (ASRS-v1.1) and ADHD Rating Scale-IV were used to assess self-reported symptoms of ADHD. A voxel-wise and atlas-based approach was used to identify changes in the brain networks. The RTHβ group reported behavioral symptoms similar to those of ADHD. We found evidence of weaker network integration of the lingual and fusiform gyri in the RTHβ group, which was mainly driven by weaker connectivity to the bilateral insula and supplementary motor cortex. Functional connectivity between regions of the default mode network (angular gyrus/middle temporal gyrus) and regions of the cognitive control network (bilateral middle frontal gyrus) was increased in RTHβ patients compared to healthy controls. Increased connectivity between regions of the default mode network and the dorsolateral prefrontal cortex is frequently reported in ADHD and is interpreted to be associated with deficits in attention. Our finding of weaker connectivity of the lingual gyrus to the bilateral insula (salience network) in RTHβ patients has also been reported previously in ADHD and may reflect decreased habituation to visual stimuli and increased distractibility. Overall, our observations support the notion of neuropsychological similarities between RTHβ and ADHD.

Event-related brain potentials to typing errors in transparent and intransparent German words

Error detection in typing is crucial for assessing the adequacy of ongoing actions, leveraging both predictive mechanisms for early detection and sensory feedback for late detection. Neurophysiological studies have supported the anticipation of errors through predictive models. This research extends the understanding of error detection in typing, focusing on the neurocognitive mechanisms underlying errors in transparent and intransparent German words. Thirty-six volunteer students typed out aurally presented words, classified as either orthographically transparent or intransparent, on a computer keyboard without the possibility of correction. Because of poor spelling or excessive artifacts, the final sample comprised 27 participants. Event-related potentials (ERPs) were obtained time-locked to key presses, and behavioral data on typing correctness and speed were collected. A higher error rate and longer latency for intransparent words compared to transparent ones were found, suggesting the complexity of spelling impacts typing correctness. Post-error slowing was observed, aligning with increased cognitive control following errors. ERPs revealed a negative component akin to the error-related negativity (ERN) for typing errors, with a pronounced ERN-like negativity preceding erroneous key-presses, particularly for intransparent words. The study provides evidence of the cognitive and neural mechanisms underlying typing errors, highlighting the impact of orthographic transparency. The detection of an ERN-like negativity before erroneous key-presses, especially in typing intransparent words, underscores the brain's use of predictive mechanisms for error detection.

Adult ADHD: it is old and new at the same time - what is it?

Even though the number of studies aiming to improve comprehension of ADHD pathology has increased in recent years, there still is an urgent need for more effective studies, particularly in understanding adult ADHD, both at preclinical and clinical levels, due to the increasing evidence that adult ADHD is highly distinct and a different entity from childhood ADHD. This review paper outlines the symptoms, diagnostics, and neurobiological mechanisms of ADHD, with emphasis on how adult ADHD could be different from childhood-onset. Data show a difference in the environmental, genetic, epigenetic, and brain structural changes, when combined, could greatly impact the behavioral presentations and the severity of ADHD in adults. Furthermore, a crucial aspect in the quest to fully understand this disorder could be through longitudinal analysis. In this way, we will determine if and how the pathology and pharmacology of ADHD change with age. This goal could revolutionize our understanding of the disorder and address the weaknesses in the current clinical classification systems, improving the characterization and validity of ADHD diagnosis, specifically those in adults.

Relationship between thyroid hormones and central nervous system metabolism in physiological and pathological conditions

Thyroid hormones (THs) play an important role in the regulation of energy metabolism. They also take part in processes associated with the central nervous system (CNS), including survival and differentiation of neurons and energy expenditure. It has been reported that a correlation exists between the functioning of the thyroid gland and the symptoms of CNS such as cognitive impairment, depression, and dementia. Literature data also indicate the influence of THs on the pathogenesis of CNS diseases, such as Alzheimer's disease, epilepsy, depression, and Parkinson's disease. This review describes the relationship between THs and metabolism in the CNS, the effect of THs on the pathological conditions of the CNS, and novel options for treating these conditions with TH derivatives.

Thyroid Hormone Resistance: Multicentrical Case Series Study

Resistance to thyroid hormone syndrome (RTHS) is defined as increased thyroxine and triiodothyronine associated with normal or increased thyrotropin. This is usually due to a pathogenic variant of the gene coding for thyroid hormone receptor B (THRB). THRB is a rare genetic disorder characterized by an altered response of target tissue to the thyroid hormone action. Retrospective cross-sectional observational study with diagnosis of RTHS evaluated in secondary and tertiary hospitals for 6 years, from 2014 to 2020, in order to describe variables including age, sex, anthropometric data, clinical and biochemical characteristics of patients, who were divided according to age, in a pediatric group from 0 to 14 years (index cases), and an adult group composed of adult relatives of index cases. A molecular analysis of the THRB gene was performed. The total retrospective cohort included 7 pediatric patients and 15 adults. We found 22 cases with a clear male predominance (14/22). Mean age is 24.8 years old (22 days-70 years). Patients were referred because of symptoms 18.2% (4/22), analysis results 22.7% (5/22), or familial study 59.1% (13/22). About 31.8% (7/22) cases show goiter, 31.8% (7/22) sympathetic symptoms and 13.6% (3/22) abnormalities in behavior. In most cases, 77.3%, (17/22) show familial background of thyroid abnormalities. It is important to remark that 18.2% (4/22) relatives received previous incorrect treatments such as thyroidectomy, because of wrong diagnosis. In conclusion, a better understanding of RTHS, its prompt molecular diagnosis and genetic counseling, could avoid unnecessary tests and inappropriate treatments.

Endocrine disrupting chemicals and thyroid hormone action

Thyroid hormones (predominantly thyroxine, T4, and triiodothyronine, T3) are essential for normal development and for adult physiology. There are several challenges, however, that make identifying chemicals that produce adverse effects by interfering with the thyroid system difficult. First, individual variability in serum concentrations of thyroid hormones represent only about 10% of the population reference range that is considered to be "normal." This means that populations studies evaluating the relationship between chemical exposure and serum thyroid hormones must be large enough to overcome this internal variance. In addition, we know that there are chemicals that do not produce changes in thyroid hormone levels, but nevertheless impact thyroid signaling in target tissues. A good example is that of polychlorinated biphenyls (PCBs). PCB exposure during development are clearly associated with cognitive deficits in humans. But PCB exposure isn't uniformly associated with a reduction in serum thyroid hormone in human populations despite mechanistic studies showing that PCBs reduce serum T4 in animals. In contrast, perchlorate is a chemical that inhibits iodide uptake, thereby reducing thyroid hormone synthesis and serum hormone levels. Human studies have been variable in identifying a relationship between thyroid hormone and perchlorate exposure, but studies also show that dietary iodine, cigarette smoking and other factors can modify this relationship. The conclusion is that identifying chemicals that interfere with thyroid hormone could depend on in vitro analysis of chemicals that interact with different proteins important for thyroid hormone to function properly.

Molecular and clinical characteristics of congenital hypothyroidism in a large cohort study based on comprehensive thyroid transcription factor mutation screening in Henan

BACKGROUND

Congenital hypothyroidism (CH), the most common neonatal endocrine disorder worldwide, can be caused by variants in thyroid transcription factor (TTF) genes including NKX2-1, FOXE1, PAX8, NKX2-5 and HHEX. This study aims to perform targeted next-generation sequencing (NGS) panel for comprehensive mutation screening on these genes in a cohort of 606 CH patients with various types from Henan Province, China, to investigate the mutation rate of TTF genes, and to analyze the clinical, biochemical and molecular characteristics of our CH cohort.

METHODS

High-throughput sequencing combined with statistical calculation were applied for mutation screening and analyses of the clinical data.

RESULTS

Twenty-two likely disease-causing monoallelic mutations in the TTF genes were identified in our cohort (3.63%, 22/606). Mutated PAX8 was the most predominant genetic alteration among these TTF mutations. Interestingly, PAX8 defects were only found in TD cases and variants in the five TTF genes were detected in gland in situ (GIS) patients. CH patients with the same genotype may have significant phenotypic variability and permanent CH (PCH) patients in the GIS group were significantly fewer than those in the TD group.

CONCLUSIONS

Our study showed the estimated TTF mutation rate among CH cases was 3.63% in Henan Province and genetic alternations in TTF genes played a role not only in TD but also in GIS, especially in goiter. Although we speculated that the five TTF genes may be involved in certain steps of thyroid hormone biosynthesis, more researches are needed to verify the conclusions of the present study.