Written by: Ebtihal Mohsen, Shaima Alhosani
Introduction to Down Syndrome
Down syndrome (DS) is the most recognized genetic cause of intellectual disability. Extra genetic material from chromosome 21 leads to multiple malformations and medical conditions that affect life expectancy and quality of life. Children with DS frequently experience endocrine disturbances, especially thyroid dysfunctions, affecting 28%-40% of these patients. (Belfiore et al.2024)(Szeliga et al., 2022)
Thyroid disease is common in the DS population, with subclinical hypothyroidism (SH) affecting 25% to 60% of patients. Elevated TSH indicates SH while thyroid hormone levels are normal. In DS infants, subclinical thyroid dysfunction (STD) may occur due to delayed HPT axis maturation, usually requiring no treatment. Blood tests should be done every 6-12 months. DS patients also show a higher incidence of autoimmune disorders like Hashimoto’s thyroiditis (HT), with autoantibodies found in 13%-34% of cases and earlier diagnoses noted in DS individuals. (Gay, 2023)
The most common hormonal pattern in HT is subclinical hypothyroidism (SH), then overt hypothyroidism. TSH levels must be monitored, with treatment needed if levels exceed 10 mIU/L. Higher baseline TSH increases the risk of worsening thyroid status, and SH and HT patients can progress to Grave’s disease. Treatment for SH is debated, especially for patients over 65, those with goiter, HT, TA positivity, and individuals with Down syndrome needing regular assessments. (Gay, 2023)
Understanding the Thyroid Gland
The thyroid gland, resembling a butterfly, is located in the lower neck and has two lobes connected by an isthmus. Weighing about 25 g in females and 30 g in males, it contains numerous follicles filled with colloid. Follicular cells produce thyroxine (T4) and triiodothyronine (T3), while parafollicular cells produce calcitonin for calcium metabolism. (Szeliga et al., 2022)
On the thyroid gland are tiny glands that are shaped like rice grains, called parathyroid glands. There are usually four parathyroid glands. Each parathyroid gland weighs about 0.5 g. Parathyroid glands produce the parathyroid hormone (PTH). It also plays a role in calcium metabolism (Yahia et al., 2012).
The thyroid gland is regulated by thyroid-stimulating hormone (TSH) from the pituitary gland. Low TSH causes hypothyroidism in dogs, cats, horses, and humans, resulting in symptoms like puffy eyes, low energy, and weight gain. High TSH leads to hyperthyroidism, especially in older cats, causing excessive thirst and weight loss due to benign thyroid growth. Medications can inhibit hormone production in humans. (Puga et al.2022)
Thyroid Disorders in Individuals with Down Syndrome
Thyroid dysfunctions are common in children with Down syndrome, affecting 28%–40% of patients, primarily presenting as hypothyroidism. Subclinical hypothyroidism occurs in 25% to 60% of DS cases and is linked to comorbidities, gender, and age. Regular screening is recommended as thyroid hormone function may decline over time in initially normal patients. (Szeliga et al., 2022)
The diagnosis of SH occurs when serum TSH is elevated (over 4.5 mU/L in infants) while fT4 and fT3 remain normal. There are concerns regarding SH diagnosis in infants with DS, as thyroid dysfunction may be transient. DS is linked to autoimmune thyrotoxicosis and Hashimoto’s thyroiditis, with autoantibodies found in 13%-34% of patients. Those with both conditions are diagnosed earlier and have a higher incidence of extra-thyroidal autoimmune disorders. The hormonal pattern typically shows SH evolving to overt hypothyroidism. (Burgard et al.2023)
Hypothyroidism and Down Syndrome
Individuals with Down syndrome (DS) are at increased risk of obesity due to metabolic issues linked to thyroid hormones (TH). Hypothyroidism (Hu) results in low TH levels, leading to various symptoms. Hashimoto’s thyroiditis (HT), an autoimmune condition, elevates thyroid autoantibodies (TA) and impairs thyroid function (TD), indicated by high TSH levels. TD prevalence in DS lies between 22-52%. Research exploring thyroid hormone status in DS patients facing weight challenges is limited. This study examines the relationship between TD and obesity (OB) in children and adolescents with DS. (Szeliga et al., 2022)(Niegawa et al., 2017)
A total of 118 participants from Romania and Japan with a westernized diet and lifestyle were surveyed, divided into non-hypothyroid (Hu) and hypothyroid (non-Hu) groups. The Hu group was further split into treated and untreated, revealing higher obesity in untreated individuals. Non-Hu subjects had increased BMI Z-scores with age, while the hypothyroid group showed no change. Untreated individuals also had more obese BD children.
3.2. Hyperthyroidism and Down Syndrome
Hyperthyroidism is a common disorder characterized by excess thyroid hormone, leading to a higher basal metabolic rate. The thyroid, a significant endocrine gland, synthesizes and releases these hormones. Increased hormone synthesis is the primary cause of excess release. This condition can be particularly concerning in Down syndrome patients who show recurrent hyperthyroid symptoms and low I-123 uptake in the thyroid. (Niegawa et al., 2017)
Weight management is vital for individuals with Down syndrome approaching adulthood due to obesity risk. Hypothyroidism contributes to weight gain, which can result in complications like Type 2 diabetes, iron deficiency, sleep apnea, and cardiovascular issues. The risk of gaining weight increases during transitions in care, especially after school services end. (Szeliga et al., 2022)
Hyperthyroidism is a rare thyroid issue in Down syndrome, typically marked by fatigue. A 123I thyroid scan can help exclude Graves’ disease with low uptake. Though excessive hormone-related hyperthyroidism is rare here, individuals face higher risks of thyroid problems, including congenital dysgenesis, autoimmune thyroiditis causing hypothyroidism, neoplastic changes, and complications from treatment.
Impact of Thyroid Function on Metabolism
Evidence shows individuals with Down syndrome are often heavier than their non-DS counterparts and face more thyroid issues that are harder to regulate. This condition can result in obesity, Alzheimer’s, and reduced lifespan. Understanding these mechanisms could enhance the quality of life for those with Down syndrome, necessitating further exploration of the link between Down syndrome, thyroid function, and metabolism.
The thyroid, shaped like a butterfly, is crucial for producing hormones such as triiodothyronine (T3) and thyroxine (T4), which affect metabolism and development. Untreated hypothyroidism can increase BMI and fat mass. KD signals a weight above 95% of age- and sex-specific BMI, while obesity is defined as a weight more than five SD from the mean or a BMI over 30 kg/m2. This worsens metabolic syndrome, especially in those with Down syndrome, emphasizing the need for further research. Educating those on thyroid function may help with weight management. (de Fátima dos Santos Teixeira et al., 2020)
Metabolism is a regulated process influenced by hormones, neurotransmitters, nutrition, and diet. Weight-related factors like dietary intake, physical activity, genetics, and hormonal mechanisms vary between adults with Down syndrome (DS) and healthy individuals. Weight management for those with DS should emphasize diet and physical activity. Research indicates DS metabolism may be slower than typical but is affected by modifiable factors that need further study.
Weight Management Challenges in Down Syndrome
Youth with Down syndrome (DS) may be more prone to obesity than those without due to various factors. While some obesity risk factors are universal, certain health conditions specific to DS can affect energy intake and expenditure, leading to weight gain. Weight management for youth with DS must address their unique needs; conventional strategies for typically developing youth may not be suitable and could be harmful. Understanding specific risk factors for weight gain in DS is vital for effective intervention planning, implementation, and evaluation, as well as identifying at-risk youth with DS. (T. Ptomey et al., 2023)
DS is linked to various health issues that affect dietary and physical activity patterns in youth, potentially leading to obesity. These include thyroid dysfunction, OSA, seizure disorders, and joint issues. Thyroid dysfunction occurs in 15-35% of children with DS and is more common than in those without DS. It significantly influences resting metabolic rate, contributing to obesity among those with hypothyroidism. While it is a frequent cause of weight gain in overweight youth with DS, it can be effectively managed through medication and thyroid function tests. (Yahia et al., 2012)
Common Weight Issues
Obesity develops more frequently in individuals with Down syndrome (DS) and is harder to treat. A cohort of 1822 from 1994 shows that the incidence of overweight or obesity in DS children correlates with age and BMI compared to wild-type children. Nearly 40% of children under 3 years are obese. Current data indicate that obesity is a growing public health issue for those with DS. This review highlights common endocrinopathies associated with obesity in the DS population. (Yahia et al., 2012)
Thyroid dysfunctions are common in children with Down’s syndrome (DS), observed in up to 54% of cases. Attention to these dysfunctions is crucial as they can positively influence the prediction of psychomotor development and guide treatments like levothyroxine supplementation. This publication reviews thyroid dysfunctions in DS, discussing both hypo- and hyperthyroidism, mechanisms of elevated thyroid-stimulating hormone, and some medications causing non-immune hyperthyroidism. Recommendations for thyroid examinations and hypothyroidism treatment in these children are also included. (Szeliga et al., 2022)
Psychosocial Factors
Down syndrome (DS), or Trisomy 21, affects roughly 315,000 individuals in the U.S., with those affected having a higher obesity risk, averaging a BMI of 31 kg/m², which can lead to chronic diseases. Evolutionary factors might contribute to this obesity tendency, particularly the idea of a “thrifty genotype” due to gene loss. Unlike apes, humans lack metabolic responses to stress that prevent weight gain, resulting in fat accumulation. Abdominal obesity links to insulin resistance, hypertension, dyslipidemia, and inflammation, constituting metabolic syndrome. While there’s no agreed-upon definition for metabolic syndrome in DS, future research should define thresholds related to obesity. Strategies to combat obesity include promoting healthy lifestyles, encouraging play, limiting screen time, providing food education, restricting unhealthy foods, and using non-food rewards for active behavior. Screening and monitoring health can support these interventions. (Yahia et al., 2012)(T. Ptomey et al., 2023)
The Role of Diet in Managing Weight
Diet plays a vital role in growth and development, making balanced nutrition essential for health, particularly in young individuals. It helps prevent congenital defects and chronic diseases influenced by poor diets, like obesity and diabetes. Overweight children with Down syndrome show unique features compared to typical obesity cases. Social and environmental factors also influence dietary behavior differently in children with and without Down syndrome, impacting meal times, snack choices, and parental diets. Analyzing these habits with family factors offers insights into obesity’s environmental influences, especially in children with developmental disabilities. (Yahia et al., 2012)
Few studies exist on dietary habits in children with Down syndrome and body weight. No research specifically examines the relationship between these dietary habits, child weight, and parental factors. Children with Down syndrome display different eating behaviors than typically developing peers, resulting in unhealthy patterns like lower vegetable intake and higher fast-food consumption. In typically developing children, diet correlates with BMI z-scores, highlighting the need to study these associations for better understanding. (Hielscher et al.2023)
Nutritional Needs
Nutritional needs (including nutrient and food group intake): What nutrients or food groups are people with Down syndrome (DS) at risk for not eating adequately? How do weight status and age affect nutritional intake? What role does food texture/ food-medicine interaction play?
Youth with Down syndrome (DS) often consume insufficient whole grains, fruits, vegetables, potassium, fiber, calcium, and Vitamin D. Nutrient intake generally decreases with age, while fiber intake increases. Overweight or obese youth typically eat fewer whole grains and vegetables. These variations can result from physiological reactions, eating habits, and food accessibility. Consequently, youth with DS often have lower nutrient density compared to neurotypical peers, risking deficiencies. Clinicians must identify these shortfalls to improve nutrition education and interventions, especially for older and overweight individuals. (Roccatello et al., 2021)(T. Ptomey et al., 2023)
Dietary education and environmental changes can enhance understanding and consumption of crucial food categories. Introducing whole grains in popular items like breads, pizza crusts, and tortillas could effectively boost intake. Educating people about the benefits of fiber, potassium, calcium, and Vitamin D may encourage them to incorporate these foods into their diets.
Dietary Recommendations
Limited studies on dietary recommendations for individuals with Down syndrome (DS) contrast with extensive literature for others. This paper summarizes evidence and offers dietary recommendations for youth with DS.
Youth with DS should eat a diet high in fruits, vegetables, whole grains, lean proteins, and low-fat dairy while limiting processed foods, added sugars, and saturated fats. This aligns with the Dietary Guidelines for Americans. (T. Ptomey et al., 2023)
Multiple studies on the dietary intake of youth with Down Syndrome (DS) indicate overall low dietary quality, which correlates with higher BMI. This aspect requires more attention from researchers and practitioners, urging more longitudinal studies to understand how various individual, familial, social, and environmental factors influence dietary habits. (Belleri et al.2024)
Weight management is crucial for improving health behaviors and quality of life for youth with Down syndrome (DS). They face a higher risk of obesity compared to typically developing youth, particularly among females. These differences may stem from biological factors. Youth with DS are more susceptible to obesity due to both syndrome-related factors and environmental influences. (Yahia et al., 2012)
Exercise and Physical Activity
Descending locomotion strategies in kindergarten children with Down syndrome.
Exercise and physical activity are essential for weight management, crucial in community and family efforts to prevent obesity and related conditions in youth with Down syndrome. While the youth in this report effectively achieved the goal of 30 minutes of moderate-to-vigorous exercise at least 4 days a week, maintaining this over the long term may be challenging. Programs in sports, recreation, and swimming can help youth develop necessary skills and interests in physical activity. (T. Ptomey et al., 2023)
Family-based programs will promote family support for healthy behaviors at home, laying the groundwork for long-term behavior changes. Parents require encouragement to engage in physical activity, and modifying the physical environment is crucial for creating more opportunities for it. Schools should assess their physical education and recess programs to evaluate the time dedicated to inclusive physical activities for all students.
Families can adopt strategies like walking or biking to school, having outings to parks or gyms, or creating home obstacle courses. They should also explore free websites for aerobic and strength exercises, and limit screen time. (Alico Lauria, 2019)
Benefits of Regular Exercise
Physical activity is crucial for improving cognitive deficits in adults with Down syndrome. Early resistance training studies showed improved fitness and performance while ensuring safety. This training enhances exercise outlook and lowers depression rates, uplifting emotional health. Nonetheless, physical activity remains low among this group, increasing obesity and metabolic disease risks. They also experience higher accident rates, impacting quality of life. Resistance training effectively boosts strength, balance, motor function, and benefits cognition, motor skills, and mood. (M. Post et al., 2022)
The study evaluated a nutrition and exercise intervention for teens aged 14 to 19 with Down syndrome. Body composition was measured through body mass index before and after the intervention. The intervention group exercised more than the waitlist group, indicating effectiveness. Minor body composition changes suggest a longer program may be needed. Limitations included insufficient power to detect nutrition knowledge changes, though feedback was positive. Future research should explore nutrition strategies, exercise trials, and parental involvement. (Alico Lauria, 2019)
Creating an Exercise Plan
An exercise plan is essential for families or providers to help individuals with Down syndrome develop a lifelong, enjoyable exercise habit. The plan should include fundamental components. If individuals grasp basic exercise concepts, have free time, or participate in group settings, joint exercise opportunities can be arranged. Plans should prioritize imitation, accuracy, and then speed or consistency of movements. (Alico Lauria, 2019)(M. Post et al., 2022)
Aerobic exercise is often the initial focus, with various modes like walking, cycling, or sports being introduced. Intensity should be gradually increased, followed by a stepwise increase in session duration after achieving an adequate aerobic capacity. Patience is crucial, as individuals with Down syndrome typically exhibit lower aerobic capacity and slower learning. Fostering self-awareness of body and heart fitness is essential, using methods like monitoring heart rate or assessing energy levels with tests to promote heart health awareness.
Certain groups may not be suitable. A family history of Down syndrome is significant. It’s beneficial to partner with a suitable community member. Engaging in the same sports weekly might prevent poor fits. Early education and government support are essential to expand access to sports.
Strategies for Caregivers
Pediatricians must monitor the weight of children with Down syndrome (DS) due to high obesity rates linked to low energy expenditure, energy-dense foods, and sedentary behavior. Lower aerobic capacity can result in higher body fat, necessitating increased physical activity for weight maintenance. While family-based weight management programs work for non-DS children, more research is needed for those with DS. Families should understand caloric intake and food consumption. Treatment strategies use studies on healthy children, focusing on family challenges and promoting positivity. While resources for healthy eating exist, specific research for DS children’s obesity management is scarce. Families should track diet and activity regularly, encouraging healthy habits. Recommendations for youth with DS include family-style meals and limiting screen time to one hour daily. (T. Ptomey et al., 2023)(Yahia et al., 2012)
Supporting Healthy Habits
In Down syndrome (DS), medical issues like hypothyroidism and obstructive sleep apnea are common and can lead to unhealthy weight. Clinicians and families should ensure youth with DS are regularly screened for these issues, especially if no prior assessments have been made. Depending on the medical condition, more frequent tests may be necessary. Weight management strategies should be individualized, considering these underlying medical issues and their impact. (T. Ptomey et al., 2023)
Identifying barriers to healthy eating and activity is essential. A personalized plan should track health behavior targets and monitor weight management progress tailored to individual preferences. Parents need to learn supportive techniques, model healthy habits, and minimize unhealthy influences.
Families should encourage their youth by praising healthy behaviors that aid weight management. During counseling visits, clinicians should endorse adherence to recommendations and share positive outcomes from these strategies. It’s essential to communicate positive regard without shaming the child for their weight, instead focusing on their positive attributes.
Navigating Healthcare Services
Navigating healthcare for individuals with Down syndrome (DS) and their caregivers is tough. Critical screenings like health assessments are often missed, despite higher risks for obesity and hypothyroidism. Clinicians need more support to follow policies and reduce disparities. Implementing annual health checks for adults with DS is essential.
Healthcare providers may not fully understand the challenges faced by those with Down Syndrome (DS), such as inadequate screenings. Children with DS often have difficulty processing information, leading to short interactions with primary care providers (PCPs). Clinician assumptions can obstruct support. It’s essential for health professionals to connect with DS individuals and families to enhance awareness and services. Health organizations should focus on effective interventions and assess the efficacy of screening tests. (Alico Lauria, 2019)(Puga et al.2022)
Childhood obesity causes long-term health problems, especially in children with Down syndrome (DS), who often gain weight early and have a higher peak BMI. Monitoring their height and weight is crucial, as definitions of overweight vary. Local guidelines must consider dysmorphic features and enable referrals for growth services. Family-based behavioral interventions are essential. Addressing obesity in DS reduces health disparities; recent reports highlight the connection between oxidative stress and obesity. (Liang et al.2023)
Studies show a link between decreased thyroid function and obesity, yet few compare these in obese children with and without the disorder. This study investigated leptin, insulin, and thyroid hormone levels in obese children and adolescents with DS versus those without. (Yahia et al., 2012)
Conclusion
The exploration of the connection between Down syndrome, thyroid function, and weight management is essential because individuals with other genetic syndromes have lower incidence of hypertension and reduced risk of developing obesity compared to the general population. Possessing the least duplicated genomic element, the 21 genes that exert the syndromic phenotype of Down syndrome, would have suggested the most extreme metabolic disadvantage, but individuals with Down syndrome show a greater metabolic advantage when compared to other genetic syndromes and the general population. To preserve the brevity necessary to merit publication, the potential metabolic interactions linking the various hormones, genes, and other products regarded to be beneficial or damaging to individuals with Down syndrome is withheld for inclusion in a subsequent paper.
The significantly increased risk of thyroid dysfunction in children with Down syndrome suggests the need for surveillance of thyroid function. The high prevalence of weight problems in children with Down syndrome should be viewed in the context of the high burden of thyroid dysfunction, as one influential factor. Young children, 4–6 years of age, with poorly controlled or newly diagnosed hypothyroidism gain weight. While the evidence of benefit in children with well-controlled hypothyroidism is lacking, weight and thyroid function measurements should be obtained concurrently during the following visit. Some clinics could add or eliminate weight-based hypothetical diagnoses if the feasibility for weight measurement is problematic.
The study is limited by the quality of the data and the inherent bias in clinical evaluations. Other environmental factors such as medications, diet, and physical activity levels could differ, but few centers have comprehensive epidemiologic survey instruments for these variables. Regardless of the variety of clinics, the pediatricians and endocrinologists have established quality metrics using adherence to evidence-based guidelines, and children who meet weight-based goals are likely seen less frequently. Children with Down syndrome are disproportionately affected by weight and thyroid problems, and systematic screening for both may confer beneficial health effects on the greater population. High utilization rates of weight-for-height and thyroid measurements were observed in following up children with Down syndrome and these health metrics should be targeted for other children with overweight and obesity in the vast majority of clinics.
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