Reversible Affective Symptoms and Attention Executive Control Network Impairment Following Thyroid Function Normalization in Hyperthyroidism

Apathetic hyperthyroidism in an elderly patient presenting with psychomotor retardation

ABSTRACT

Hyperthyroidism in the elderly population is often associated with atypical, blunted, or nonspecific signs and symptoms, also known as apathetic hyperthyroidism (AH). The absence of the classical hyperkinetic clinical presentation can be confused with the normal aging process, or other diseases, and often leads to misdiagnosis, delayed treatment, and negative outcomes for elderly patients. We provide a case study of an elderly patient to illustrate the atypical presentation of AH. The vignette also highlights a diagnostic and treatment approach based on geriatric medicine fundamentals and evidence-based research. We then review the multiple factors and pathogenetic mechanisms contributing to endocrine disruptors and the paucity of hyperadrenergic signs and symptoms in the elderly with hyperthyroidism. Additionally, the article contrasts the symptomatology and diagnostic profile between primary hyperthyroidism and AH. Finally, we provide an evidence-based, patient-centered approach to manage AH in the elderly population. We recommend that nurse practitioners cultivate illness script inclusive of atypical presentations to guide their clinical decision making. Psychomotor retardation with or without cardiovascular symptoms warrant a high degree of suspicion and the initiation of laboratory studies, including thyroid functions to confirm or rule out hyperthyroidism.

Impaired learning and memory generated by hyperthyroidism is rescued by restoration of AMPA and NMDA receptors function

Hyperthyroidism has been identified as a risk factor for cognitive disorders. The hippocampus is a key brain region associated with cognitive function, among which excitatory synapse transmission plays an important role in the process of learning and memory. However, the mechanism by which hyperthyroidism leads to cognitive dysfunction through a synaptic mechanism remains unknown. We investigated the synaptic mechanisms in the effects of hyperthyroidism in an animal model that involved repeated injection of triiodothyronine (T3). These mice displayed impaired learning and memory in the Novel object recognition test, Y-maze test, and Morris Water Maze test, as well as elevated anxiety in the elevated plus maze. Mature dendritic spines in the hippocampal CA1 region of hyperthyroid mice were significantly decreased, accompanied by decreased level of AMPA- and NMDA-type glutamate receptors in the hippocampus. In primary cultured hippocampal neurons, levels of AMPA- and NMDA-type glutamate receptors also decreased and whole-cell patch-clamp recording revealed that excitatory synaptic function was obviously attenuated after T3 treatment. Notably, pharmacological activation of AMPAR or NMDAR by intraperitoneal injection of CX546, an AMPAR agonist, or NMDA, an NMDAR agonist can restore excitatory synaptic function and corrected impaired learning and memory deficit in hyperthyroid mice. Together, our findings uncovered a previously unrecognized AMPAR and NMDAR-dependent mechanism involved in regulating hippocampal excitatory synaptic transmission and learning and memory disorders in hyperthyroidism.

Neurometabolite Changes in Hyperthyroid Patients Before and After Antithyroid Treatment: An in vivo 1H MRS Study

Purpose: Patients with hyperthyroidism have frequent neuropsychiatric symptoms such as lack of attention, concentration, poor memory, impaired executive functions, depression, and anxiety. These neurocognitive impairments such as memory, attention, and executive functions appear to be associated with dysfunction in brain regions. This study was conducted to investigate the metabolic changes in the brain subcortical regions, i.e., posterior parietal cortex and dorsolateral prefrontal cortex (DLPFC), in patients with hyperthyroidism before and after antithyroid treatment using proton magnetic resonance spectroscopy (¹H MRS). Materials and Methods: We collected neuropsychological and ¹H MRS data from posterior parietal cortex and DLPFC, in both control (N = 30) and hyperthyroid (N = 30) patients. In addition, follow-up data were available for 19 patients treated with carbimazole for 30 weeks. The relative ratios of the neurometabolites were calculated using the Linear Combination Model (LCModel). Analysis of co-variance using Bonferroni correction was performed between healthy controls and hyperthyroid patients, and a paired t-test was applied in patients at baseline and follow-up. Spearman's rank-order correlation was used to analyze bivariate associations between thyroid hormone levels and metabolite ratios, and the partial correlation analysis was performed between neuropsychological scores and metabolite ratios, with age and sex as covariates, in the patients before and after treatment. Results: Our results revealed a significant decrease in choline/creatine [glycerophosphocholine (GPC) + phosphocholine (PCh)/creatine (tCr)] in both the posterior parietal cortex and DLPFC in hyperthyroid patients, and these changes were reversible after antithyroid treatment. The posterior parietal cortex also showed significantly reduced glutamate/creatine (Glu/tCr), (glutamate + glutamine)/creatine (Glx/tCr), and increased glutathione/creatine (GSH/tCr) ratios in the hyperthyroid patients over control subjects. In DLPFC, only (N-acetyl aspartate + N-acetyl aspartyl-glutamate)/creatine (NAA + NAAG)/tCr was increased in the hyperthyroid patients. After antithyroid treatment, (GPC + PCh)/tCr increased, and Glx/tCr decreased in both brain regions in the patients at follow-up. Gln/tCr in the posterior parietal cortex was decreased in patients at follow-up. Interestingly, (GPC + PCh)/tCr in DLPFC showed a significantly inverse correlation with free tri-iodothyronine (fT3) in hyperthyroid patients at baseline, whereas NAA/tCr showed positive correlations with fT3 and free thyroxine (fT4) in hyperthyroid patients before and after antithyroid treatment, in the posterior parietal cortex. In DLPFC, only (NAA + NAAG)/tCr showed positive correlations with fT3 and fT4 in the patients before treatment. Conclusion: The overall findings suggest that all the brain metabolite changes were not completely reversed in the hyperthyroid patients after antithyroid treatment, even after achieving euthyroidism.

Risk Preferences, Rationality of Choices, and Willingness to Pay for Preventive Medicine in Patients with Graves' Thyrotoxicosis

PURPOSE

Patients with thyrotoxicosis show neuropsychological changes, and these may damage the quality of informed consent in clinical practice. Therefore, we examined patients' real-life preferences to assess whether change in risk preferences was dependent on thyroid function state.

PATIENTS AND METHODS

The participants were 86 patients who were newly diagnosed with Graves' thyrotoxicosis between 1 January and 31 December 2018 (group A), and an additional 33 euthyroid patients diagnosed before 2018 (group B). In a survey conducted via a questionnaire based on the concept of behavioral economics, we sought to determine risk preferences, rationality of choices, and other relevant factors. An identical second survey was completed 6-12 months later by 36 patients in group A after their thyroid functions had been normalized by treatment, and by 11 euthyroid patients in group B. We performed paired analysis of the first and second surveys in 32 patients of group A and single regression analysis of a total of 140 surveys obtained from 119 patients by combining the first and second surveys of groups A and B with serum level of FT3 as an independent variable.

RESULTS

The paired analysis indicated that there was no significant difference in any survey item. The single regression analysis revealed that willingness-to-pay (WTP) for preventive medicine and monthly average out-of-pocket (OOP) expenditure on medical care were both significantly positively associated with serum level of FT3. Patients in the hyperthyroid state tend to have high WTP for preventive medicine, which may be accelerated by the anchoring effect of OOP expenditure.

CONCLUSION

Almost all risk preferences of patients with Graves' disease are constant, rational, and reproducible in the hyperthyroid and euthyroid states. However, medical professionals should be aware that the willingness of patients with thyrotoxicosis to pay for medical costs may change after the normalization of thyroid function.

Study of Cognitive Disfunctions in Thyroid Pathology

Thyroid pathology is characterized by abnormal values of thyroid hormones that can affect the brain and can lead to cognitive impairment (attention, memory, mood), depression and anxiety. The aim of the study is to evaluate the association between the cognitive disorders and thyroid disease and the link between thyroid hormone levels FT4 and TSH in depression and anxiety. We included 130 individuals from Endocrinology Clinic of Craiova, over a period of 6 years (2014-2020), none of whom was taking thyroid medication and antidepressants. The most important symptom found in thyroid pathology is depression, which occurs in those with long-lasting illness. We obtained that 45.38% of the cases were diagnosed with depression and 46.92% with anxiety. Depressive symptoms were assessed with Hamilton scale and anxiety symptoms with the Beck scale. Regarding the impaired cognitive function, we found it in 34.7% of cases of hypothyroidism (loss of memory / lack of concentration) and for the cases with hyperthyroidism, we found changes in 51,42%.