Cognitive Function in Children With Idiopathic Subclinical Hypothyroidism: Effects of 2 Years of Levothyroxine Therapy

Ameliorative effects of thiamin on learning behavior and memory dysfunction in a rat model of hypothyroidism: implication of oxidative stress and acetylcholinesterase

Hypothyroidism causes learning and memory impairment. Considering the neuroprotective properties of thiamine (Vitamin B1), this study was conducted to investigate the effects of thiamine on acetylcholinesterase (AChE) activity, oxidative damage, and memory deficits in hypothyroid rats.In this study, 50 rats (21 days old) were randomly divided into 5 groups and treated with propylthiouracil (0.05% in drinking water) and thiamine (50, 100, and 200 mg/kg, oral) for 7 weeks. Following that, Morris water maze (MWM) and passive avoidance (PA) tests were performed. Finally, oxidative stress indicators and AChE activity were measured in brain tissue.Treatment of hypothyroid rats with thiamine, especially at 100 and 200 mg/kg, alleviated the ability to remember the location of the platform as reflected by less time spent and distance to reach the platform, during the MWM test (P < 0.05 to P < 0.001). In the PA test, the latency to enter the dark chamber and light stay time were increased in rats who received thiamine compared to the hypothyroid group (P < 0.05 to P < 0.001). In addition, thiamine increased the levels of total thiol groups and superoxide dismutase while decreasing the levels of malondialdehyde and AChE.Our results suggest that thiamine supplementation could effectively improve memory loss in a rat model of hypothyroidism. The positive effects of thiamin on the learning and memory of hypothyroid rats may be due to amelioration of redox hemostasis and cholinergic disturbance.

Subclinical hypothyroidism and digit span test performance in children: a systematic review and meta-analysis

Background The digit span (DS) test is one of the most commonly used neuropsychological tests to assess certain cognitive domains, i.e., short-term verbal memory, working memory, and attention. Subclinical hypothyroidism (SH) may be associated with a risk of cognitive impairment in children and adolescents. Objective To evaluate the association between SH and DS test performance in children. Methods Eligible studies evaluating SH and DS test performance were included in this systematic review and further assessed for risk of bias using the Newcastle Ottawa Scale. We carried out a meta-analysis using the random effects model to determine mean difference with 95% confidence interval (95%CI) for continuous data. This systematic review was conducted according to the Preview Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. Results Out of 1,511 participants in the five included studies, 129 had SH and 1,382 were euthyroid.  The quality of all studies were fair to good. Three studies were extracted for meta-analysis, with results showing a trend toward a poorer DS test performance in the SH group compared to controls, although this difference was statistically insignificant (IV -0.57; 95%CI -1.61 to 0.46; P=0.28). There was no significant heterogeneity among the included studies (I2=0%; P=0.69). Conclusion No significant association was noted between SH and the domains of cognitive function assessed using the DS test. Several intrinsic and extrinsic factors and inability of the DS test to detect subtle impairment may limit its usefulness in children.

Emotional intelligence scores in children and adolescents with subclinical hypothyroidism-correlation with serum serotonin and thyroid-stimulating hormone (TSH) concentrations

INTRODUCTION

Thyroxine is essential for nervous system development. Subclinical hypothyroidism (SCH), also known as mild thyroid failure, is associated with impaired cognitive function in children and mood disorders in adults. Serotonin is also involved in brain development as well as in mood and behavior modulation. The possible interaction between thyroid function tests, serum serotonin concentrations, and emotional intelligence (EI) was studied.

METHODS

A total of 224 schoolchildren from the Peloponnese, Greece, aged 11-19, were included in the study, of whom 26.3% had SCH. Emotional quotients (EQ), such as well-being, self-control, emotionality, and sociability, were assessed using the TEIQue-ASF questionnaire, and TSH, fT4, and serum serotonin concentrations were also evaluated.

RESULTS

Children and adolescents with SCH had a lower EQ total score (p < 0.001), EQ well-being score (p = 0.025), EQ self-control score (p = 0.029), EQ emotionality score (p = 0.029), and EQ sociability score (p = 0.010) and lower serum serotonin concentrations (p < 0.001).

CONCLUSIONS

Children and adolescents with SCH exhibited lower EI scores and lower serum serotonin concentrations when compared with age-matched healthy controls.

Long-Term Follow-Up and Outcomes of Autoimmune Thyroiditis in Childhood

Background: Autoimmune thyroiditis (AIT) is the most common cause of acquired hypothyroidism in children. The natural outcome of AIT in childhood has been reported previously however follow-up duration is generally short and results variable. Objectives: To characterize clinical and biochemical findings at presentation of AIT, evaluate long-term outcomes and assess which factors at presentation predict evolution over time. Study cohort: 201 children under 18 years of age at presentation (82% female) were enrolled. Subjects were divided into five subgroups according to thyroid stimulating hormone (TSH) level at referral. Results: Mean follow-up was 8.1 years (range 0-29 years). At presentation, 34% of patients had overt hypothyroidism, 32% subclinical hypothyroidism (SCH), 16% compensated hypothyroidism, 14% were euthyroid, and 3.7% had Hashitoxicosis. Children with overt hypothyroidism were younger (10.6 vs. 13.2 years) and had higher thyroid peroxidase antibody titers. At the time of the study, levothyroxine (LT₄) therapy was required in 26% of children who were euthyroid at presentation, 56% of SCH patients, 83-84% of those with TSH above 10 mIU/L, and 57% of those with Hashitoxicosis. Over the years, 16% of children presenting with overt hypothyroidism stopped therapy. Free T₄ at presentation was the only predictor of outcome over time. Conclusions: Our findings suggest that only 26% children who were euthyroid at presentation developed hypothyroidism, whereas over 50% of those with SCH went on to require treatment. Of those presenting with overt hypothyroidism, 16% recovered with time. The only predictive parameter for LT₄ therapy at the end of the study was free T₄ levels at presentation. Long-term follow-up is required to determine ongoing therapy needs and screen for additional autoimmune diseases.