Iron-deficiency anemia is associated with altered characteristics of sleep spindles in NREM sleep in infancy

Iron Deficiency and Vitamin D Deficiency Are Associated with Sleep in Females of Reproductive Age: An Analysis of NHANES 2005-2018 Data

BACKGROUND

Iron and vitamin D deficiencies have been implicated in sleep disturbance. Although females are more susceptible to these deficiencies and frequently report sleep-related issues, few studies have examined these associations in females.

OBJECTIVE

This study investigates the association of iron and vitamin D deficiencies on sleep in a nationally representative sample of females of reproductive age.

METHODS

We used 2 samples of 20-49-y-old non-pregnant females from National Health and Nutrition Examination Survey (NHANES) 2005-2008 (N = 2497) and NHANES 2005-2010 and 2015-2018 (N = 6731) to examine the associations of iron deficiency (ID), iron deficiency anemia (IDA), vitamin D deficiency (VDD), vitamin D inadequacy (VDI), and the joint association of both deficiencies with sleep duration, latency, and quality. Sleep outcomes were measured using a self-reported questionnaire. We used the body iron model based on serum ferritin and serum soluble transferrin receptor to identify ID, along with hemoglobin to identify IDA cases. In addition, 25-hydroxyvitamin D levels were used to determine VDD and VDI cases. Logistic regression was used to evaluate these associations, adjusting for potential confounders. In addition, we assessed the multiplicative and additive interactions of both deficiencies.

RESULTS

ID and IDA were associated with poor sleep quality, with 1.42 [95% confidence interval (CI): 1.02, 2.00)] and 2.08 (95% CI: 1.29, 3.38) higher odds, respectively, whereas VDD and VDI were significantly associated with short sleep duration, with 1.26 (95% CI: 1.02, 1.54) and 1.22 (95% CI: 1.04, 1.44) higher odds, respectively. Subjects with both nutritional deficiencies had significantly higher odds of poorer sleep quality compared with subjects with neither condition. For sleep quality, a significant multiplicative interaction was observed between ID and VDD (P value = 0.0005). No associations were observed between study exposures and sleep latency.

CONCLUSIONS

Among females of reproductive age, iron and vitamin D deficiencies are associated with sleep health outcomes. The potential synergistic effect of both deficiencies warrants further assessment.

Childhood sleep: assessments, risk factors, and potential mechanisms

BACKGROUND

Sleep problem is a highly prevalent health issue among pediatric populations across the world. In this review, we aimed to identify risk factors contributing to sleep deficiency and poor sleep hygiene in children. Potential biological, psychosocial, and environmental mechanisms as well as research gaps in the literature are also discussed.

DATA SOURCES

A comprehensive search for relevant English language full-text, peer-reviewed publications was performed focusing on pediatric sleep studies from prenatal to childhood and adolescence in a variety of indexes in PubMed, SCOPUS, and Psych Info. Both relevant data based and systematic reviews are included.

RESULTS

This paper summarizes many risk factors for childhood sleep problems, including biological (e.g., genetics, gender, age and puberty, prenatal factors, postnatal factors); nutritional (e.g., macronutrients, micronutrients, omega-3 fatty acids, obesity); environmental (e.g., heavy metals, noise, light, air pollution); interpersonal (e.g., family, exposure to violence, screen media use, physical injury); and community/socioeconomic variables (e.g., racial/ethnicity and cultural factors, neighborhood conditions and socioeconomic status, school factors, public health disasters/emergencies), to better understand the development of sleep problems in children.

CONCLUSIONS

Poor childhood sleep is a multifactorial issue affected by a wide range of prenatal and early-life biological, environmental, and psychosocial risk factors and contributors. A better understanding of these risk factors and their mechanisms is an important first step to develop future research and prevention programs focusing on pediatric sleep problems.

Behavioral sleep medicine-The need for harmonization of clinical best practice outcome measures in children and adolescents with intellectual or developmental disabilities and restless sleep

In behavioral medicine, sleep disorders, insomnia in particular, may be considered comorbidities and precipitating factors to intellectual or developmental disabilities (IDD). Nevertheless, sleep alterations have often been neglected in favor of daytime features and symptoms, albeit simple behavioral nighttime observations may disclose hypermotor features that characterize restless sleep. The root of most hypermotor restlessness is linked to central iron deficiency. The latter is often exacerbated by vitamin D deficiency (VDD), which interferes with both dopaminergic and serotonergic mechanisms. In this way, an imbalance affecting daytime behavior and mood is created. Several sleep-related motor disorders such as bruxism, periodic and aperiodic leg movements, Restless Legs Syndrome (RLS), and Restless Sleep Disorder (RSD) are commonly seen in Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorders (ASD). However, they are rarely diagnosed and often overlooked in affected children and adolescents. As a result, not only are these disorders not adequately addressed therapeutically, but their symptoms may be worsened by the side-effects of drugs used to contain disruptive daytime behavior, such as antipsychotics and antidepressants. In children with IDDs, obesity, inactivity and metabolic effects of antipsychotics often lead to Sleep Disordered Breathing (SDB), which is currently understood as an inflammatory state leading to "hyperactive" lethargy and further alterations of the hypoxic chain and vitamin D levels. Endorsing simple routine blood tests, including inflammatory markers such as C-reactive protein, ferritin, transferrin, and vitamin D levels, may favorably complement caregiver observations and ambulatory sleep recordings, leading to a sleep disorder diagnosis and consequent therapy. In fact, the treatment of SDB, RLS, and RSD has been copiously demonstrated to favorably impact vigilance, behavior, social competence, and academic skills in healthy and, to a greater extent, in IDD children. Thus, consulting and deliberating the root causes of functional and categorical diagnoses within a clinical framework may engender a more precise diagnosis and further benefit pediatric daytime and nighttime management of hyperactive behaviors.

Can Iron Play a Crucial Role in Maintaining Cardiovascular Health in the 21st Century?

In the 21st century the heart is facing more and more challenges so it should be brave and iron to meet these challenges. We are living in the era of the COVID-19 pandemic, population aging, prevalent obesity, diabetes and autoimmune diseases, environmental pollution, mass migrations and new potential pandemic threats. In our article we showed sophisticated and complex regulations of iron metabolism. We discussed the impact of iron metabolism on heart diseases, treatment of heart failure, diabetes and obesity. We faced the problems of constant stress, climate change, environmental pollution, migrations and epidemics and showed that iron is really essential for heart metabolism in the 21st century.

Association of maternal hemoglobin levels during pregnancy with sleep and developmental problems in 1‐year‐old infants: A cohort study

Background and Aims

Maternal hemoglobin concentration during pregnancy is reported to be associated with various perinatal outcomes and may also be associated with infant development. This study aims to investigate the association between maternal hemoglobin levels during early or mid‐pregnancy and sleep and developmental problems in 1‐year‐old infants.

Methods

We used the data of 66,935 pregnant women who were participants of the Japan Environment and Children's Study, a nationwide cohort study in Japan, between 2011 and 2014. Maternal hemoglobin level was examined at recruitment (mean gestational age, 15.3 weeks; SD, 2.85 weeks; range, 6–22 weeks). Information on infant sleep and development at the age of 1 year was acquired using a questionnaire. Infant development was evaluated using the Ages and Stages Questionnaire (ASQ).

Results

The mean (SD) maternal hemoglobin level was 12.0 (1.0) g/dl. Maternal hemoglobin levels were not associated with the majority of infant sleep and developmental outcomes. In the group with maternal hemoglobin <10.0 g/dl, the risk ratio (RR) for sleep at 22:00 or later was higher than that in the reference group with 11.0 g/dl ≤ hemoglobin < 14.0 g/dl (RR 1.12, 95% confidence interval = 1.00–1.25). In the analysis with maternal hemoglobin level as a continuous variable, both high and low hemoglobin levels were associated with a higher RR of a late bedtime. In addition, a low maternal hemoglobin level was associated with a higher RR for abnormal fine motor skills in the ASQ.

Conclusion

Our results suggest that a low level of maternal hemoglobin during pregnancy is associated with late bedtime and abnormal fine motor skills in 1‐year‐old infants. Conversely, a high level of maternal hemoglobin may also be associated with the infant's late bedtime.

Serum micronutrient status, sleep quality and neurobehavioural function among early adolescents

OBJECTIVE

To examine associations between serum micronutrients and neurobehavioural function and the mediating role of sleep quality in early adolescents.

DESIGN

In this cross-sectional study, peripheral blood samples were analysed for Fe and Zn levels. The Pittsburgh Sleep Quality Index and Penn Computerized Neurocognitive Battery were used to assess sleep quality and neurobehavioural function, respectively. The logistic/linear regressions and generalised structural equation modelling were performed to estimate the associations.

SETTING

Jintan, China.

PARTICIPANTS

In total, 226 adolescents (106 females) from the Jintan Child Cohort study.

RESULTS

Adolescents with low Fe (<75 μg/dl) (OR = 1·29, P = 0·04) and low Zn (<70 μg/dl) (OR = 1·58, P < 0·001) were associated with increased odds for poor sleep quality. Adolescents with low Fe and Zn were associated with fast (Fe: β = -1353·71, P = 0·002, Zn: β = -2262·01, P = 0·02) but less-accurate (Fe: β = -0·97, P = 0·04; Zn: β = -1·76, P = 0·04) performance on non-verbal reasoning task and poor sleep quality partially mediated the associations between low Fe/Zn and non-verbal reasoning (P < 0·05). Additionally, low Fe was associated with a slower reaction on spatial processing task (β = 276·94, P = 0·04), and low Zn was associated with fast (β = -1781·83, P = 0·03), but error-prone performance (β = -1·79, P = 0·04) on spatial processing ability and slower reaction speed (β = 12·82, P = 0·03) on the attention task. We observed similar trends using a cut-off point of 75 μg/dl for low serum Zn, except for the association with attention task speed (P > 0·05).

CONCLUSION

Fe and Zn deficiencies may possibly be associated with poor sleep and neurobehavioural function among early adolescents. Poor sleep may partially mediate the relationship between micronutrients and neurobehavioural function.

Anemia and insomnia: a cross-sectional study and meta-analysis

Background

Several recent genome-wide association studies suggested insomnia and anemia may share some common genetic components. We thus examined whether adults with anemia had higher odds of having insomnia relative to those without anemia in a cross-sectional study and a meta-analysis.

Methods

Included in this cross-sectional study were 12,614 Chinese adults who participated in an ongoing cohort, the Kailuan Study. Anemia was defined as hemoglobin levels below 12.0 g/dL in women and 13.0 g/dL in men. Insomnia was assessed using the Chinese version of the Athens Insomnia Scale (AIS). A total AIS score ≥6 was considered insomnia. The association between anemia and insomnia was assessed using a logistic regression model, adjusting for potential confounders such as age, sex, chronic disease status, and plasma C-reactive protein concentrations. A meta-analysis was conducted using the fixed effects model to pool results from our study and three previously published cross-sectional studies on this topic in adult populations.

Results

Individuals with anemia had greater odds of having insomnia (adjusted odds ratio [OR]: 1.32; 95% confidence interval [CI]: 1.03–1.70) compared with individuals without anemia. A significant association persisted after we excluded individuals with chronic inflammation, as suggested by C-reactive protein levels >1 mg/L (adjusted OR: 1.68; 95% CI: 1.22–2.32). The meta-analysis results, including 22,134 participants, also identified a positive association between anemia and insomnia (pooled OR: 1.39; 95% CI: 1.22–1.57).

Conclusions

The presence of anemia was significantly associated with a higher likelihood of having insomnia in adults. Due to the nature of the cross-sectional study design, results should be interpreted with caution.

The effect of sleep duration on hemoglobin and hematocrit: observational and Mendelian randomization study

STUDY OBJECTIVE

Observationally sleep duration is positively associated with hemoglobin (Hgb), whether this association is causal and consistent by sex remains unclear. Here, we assessed the association of sleep duration with Hgb and hematocrit (Hct) observationally in late adolescence in a population-representative Chinese birth cohort "Children of 1997" with validation using Mendelian randomization (MR) in adults.

METHODS

In the "Children of 1997" birth cohort (recruited = 8327, included = 3144), we used multivariable linear regression to assess the adjusted associations of sleep duration (measured as time in bed) with Hgb and Hct at 17.5 years and any sex differences. Using two-sample MR, we assessed the effect of sleep duration on Hgb and Hct, based on 61 single nucleotide polymorphisms (SNPs) applied to genome-wide association studies of Hgb and Hct in adults (n = 361 194).

RESULTS

Observationally, self-reported sleep duration was positively associated with Hct (0.034 standard deviations [SDs] per hour, 95% confidence interval [CI] 0.019 to 0.049), but not with Hgb. Using MR longer sleep increased Hct (0.077 SD per hour, 95% CI 0.035 to 0.119) and Hgb (0.065 SD per hour, 95% CI 0.020 to 0.109) using Mendelian randomization pleiotropy residual sum and outlier (MR PRESSO), with more pronounced associations in men.

CONCLUSIONS

Our novel findings indicate sleep increases both Hgb and Hct, particularly in men, perhaps contributing to its restorative qualities. Potential difference by sex and the implications of these findings warrant investigation.

Night Sleep Duration and Risk of Incident Anemia in a Chinese Population: A Prospective Cohort Study

The purpose was to study the association between sleep duration and the prevalence of anemia in Chinese people. There were 84,791 participants (men: 79.1%; women: 20.9%) aged 18–98 years in the prospective study. We divided the participants into five categories based on the individual sleep duration: ≤5 h, 6 h, 7 h(reference), 8 h, and ≥9 h. Anemia was defined based on hemoglobin <12 g/dL for men and <11 g/dL for women. The Cox proportional hazards model was used to assess the association between sleep duration and anemia. During median follow-up of 7.9 years, 2698 cases of anemia had occurred. The HRand (95% CI) of anemia (7 h as the reference group) for individuals reporting ≤5 h, 6 h, 8 h, and ≥9 h were 1.23(1.04–1.45), 1.26(1.11–1.44), 1.04(0.92–1.16) and 1.42(1.08–1.86), respectively. It showed that there was a significant interaction on the risk of anemia between sleep duration and sex in the secondary analysis (p < 0.001).The significant association between long sleepduration and anemia was found in women (HR, 2.29; 95% CI, 1.56–3.37), not in men(HR, 0.90; 95% CI, 0.60–1.34). Both short and long night sleep duration were associated with increased risk of anemia.

Association Between Non-Iron-Deficient Anemia and Insomnia Symptoms in Community-Dwelling Older Adults: The Baltimore Longitudinal Study of Aging

Background

Anemia is associated with poorer sleep in children, and clinically, anemia is linked to insomnia. However, the association between anemia and insomnia in older adults is understudied.

Methods

We examined the cross-sectional association between anemia and insomnia in 1,053 adults (71.4 ± 10.6 years) in the Baltimore Longitudinal Study of Aging. Participants were classified as nonanemic, non-iron-deficient anemic, or iron-deficient anemic based on hemoglobin, ferritin, transferrin saturation, and mean cell volume. Insomnia symptoms were evaluated by the Women's Health Initiative Insomnia Rating Scale (WHIIRS). A total score (range 0-20) was generated, and participants were also classified as having 0, 1, or 2+ symptoms.

Results

Overall, 10.5% of participants had non-iron-deficient anemia, 0.9% had iron-deficient anemia, and 88.5% had no anemia. Due to its low prevalence, the iron-deficient anemic group was dropped from analyses. In models adjusted for demographics, number of medical conditions, and Center for Epidemiologic Studies Depression Scale score, non-iron-deficient anemic individuals had significantly higher WHIIRS total scores, indicating greater insomnia severity, compared to those without anemia (predicted adjusted mean WHIIRS of 7.24 [95% confidence interval (CI): 6.40-8.08] vs 5.92 [95% CI: 5.65-6.19]). They also had twice the risk of reporting ≥2 insomnia symptoms (vs 0 symptoms; relative risk ratio = 2.20, 95% CI: 1.25-3.89).

Conclusions

Results suggest that individuals with non-iron-deficient anemia are more likely to experience insomnia symptoms than those who are nonanemic. These results may have implications for insomnia treatment or the identification of underlying frailty in individuals with sleep problems.

Iron therapy substantially restores qEEG maturational lag among iron-deficient anemic infants

OBJECTIVE

To use quantitative electroencephalography (qEEG) to assess the impact of iron-deficiency anemia on central nervous system maturation in the first year of life.

METHOD

Twenty-five infants (3-12 months old) presenting ferropenic anemia (IDA) and 25 healthy controls (CTL1), matched by age/gender with the former, were studied in two stages. Electroencephalogram during spontaneous sleep was recorded from all participants; the fast Fourier transform was calculated to obtain absolute power (AP) and relative power (RP) qEEG measures. In the first stage, a qEEG comparison between CTL1 and IDA was performed. Second stage consisted in comparing qEEG of the IDA infants before and after supplementation with iron (IDA-IS group), and comparing qEEG of the IDA-IS group with another control age-matched group (CTL2). Non-parametric multivariate permutation tests (NPT) were applied to assess differences between CTL1 and IDA groups, as well as IDA vs. IDA-IS, and IDA-IS vs. CTL2.

RESULTS

More power in slow frequency bands and less power in fast frequency bands in 64% of IDA babies were observed. NPT evinced higher alpha AP and RP (P < 0.001), less theta AP, and less delta and theta RP in CTL1 than in IDA. After iron-restoration therapy, alpha AP and RP increased while theta AP and theta and delta RP decreased, reaching almost normal values.

DISCUSSION

This work reveals CNS developmental delay through the study of qEEG (less rapid and more slow frequencies) which recovered significantly with iron supplementation. It is concluded that IDA constitutes a high risk factor for a lag of CNS maturation.

The relationship between micronutrient status and sleep patterns: a systematic review

OBJECTIVE

To review articles on the relationship of dietary and circulating micronutrients with sleep patterns, and to identify issues surrounding implications for future research and public health practice.

DESIGN

A systematic review was conducted. PubMed, Embase and Scopus were searched through January 2016.

SETTING

Both experimental and observational studies were included. However, studies that focused on secondary sleep impairment due to comorbidities were excluded.

SUBJECTS

Individuals in different age groups, from infants to older adults.

RESULTS

A total of twenty-six articles were selected. In the articles reviewed, researchers generally supported a potential role of micronutrients, particularly Fe and Mg, in the development of sleep stages among infants and in reversing age-related alterations in sleep architecture in older adults. Micronutrient status has also been linked to sleep duration, with sleep duration positively associated with Fe, Zn and Mg levels, and negatively associated with Cu, K and vitamin B12 levels. The mechanisms underlying these relationships include the impact of micronutrients on excitatory/inhibitory neurotransmitters and the expression of circadian genes.

CONCLUSIONS

Although the number of studies on the relationship between micronutrient status and sleep remains low, evidence has emerged that suggests a link between dietary/circulating micronutrients and sleep. Future research is needed to investigate the dose-dependent as well as the longitudinal relationships between micronutrient levels and human sleep across populations, test the interactions among micronutrients on sleep outcomes, and ultimately examine the clinical relevance of micronutrients on sleep health.

Sleep Spindle Deficit in Schizophrenia: Contextualization of Recent Findings

Sleep spindles are wax and waning brain oscillations at a frequency range of 11-16 Hz, lasting 0.5-2 s, that define non-rapid eye movement sleep stage 2. Over the past few years, several independent studies pointed to a decrease of sleep spindles in schizophrenia. The aim of this review is to contextualize these findings within the growing literature on these oscillations across other neuro-psychiatric disorders. Indeed, spindles reflect the coordinated activity of thalamocortical networks, and their abnormality can be observed in a variety of conditions that disrupt local or global thalamocortical connectivity. Although the broad methodological variability across studies limits the possibility of drawing firm conclusions, impaired spindling activity has been observed in several neurodevelopmental and neurodegenerative disorders. Despite such lack of specificity, schizophrenia remains the only condition with a typical late adolescence to young adulthood onset in which impaired spindling has been consistently reported. Further research is necessary to clearly define the pathogenetic mechanisms that lead to this deficit and the validity of its widespread use as a clinical biomarker.

Developmental changes in sleep and breathing across infancy and childhood

Sleep and breathing are physiological processes that begin in utero and undergo progressive change. While the major period of change for both sleep and breathing occurs during the months after birth, considered a period of vulnerability, more subtle changes continue to occur throughout childhood. The systems that control sleep and breathing develop separately, but sleep represents an activity state during which breathing and breathing control is significantly altered. Infants and young children may spend up to 12 hours a day sleeping; therefore, the effects of sleep on breathing are fundamental to understanding both processes in childhood. This review summarizes the current literature relevant to understanding the normal development of sleep and breathing across infancy and childhood.

Associations between Blood Zinc Concentrations and Sleep Quality in Childhood: A Cohort Study

Little evidence is available regarding the relationship between zinc and sleep in school children. The present study aimed to examine the cross-sectional and longitudinal associations between blood zinc concentrations and sleep quality throughout childhood. A total of 1295 children from the Jintan Child Cohort in China were included in this study. Venous blood sample of zinc and subjective sleep data were collected when the children were at preschool age (3-5 years old) and early adolescence (11-15 years old). Odds ratios (ORs) reflect the odds of the sleep quality/subdomain being at a greater impairment level associated with 1 unit increase in log zinc concentration. Cross-sectional analyses showed negative correlation of blood zinc concentrations with insufficient sleep duration (OR = 0.432, p = 0.002), sleep disturbances (OR = 0.454, p = 0.009) and poor sleep quality (OR = 0.559, p = 0.049) in adolescence, but no association at preschool age (p > 0.05). Longitudinal analyses indicated that blood zinc concentrations at preschool age predict poor sleep efficiency (OR = 0.186, p = 0.000) and poor sleep quality (OR = 0.358, p = 0.020) in adolescence. Our findings suggest that sufficient zinc concentration is associated with good sleep quality, dependent on the developmental stage in childhood. Future interventional research is warranted to examine the short and long-term effect of zinc status on sleep heath.

Inhibitory control in otherwise healthy overweight 10-year-old children

BACKGROUND

Preventing obesity is a worldwide public health priority. In vulnerable children living in obesogenic environments, with easy access to high-caloric food, alterations in inhibitory control functions might favor excessive food intake and affect energy regulation. We hypothesized that overweight/obese children would present lower inhibitory control in comparison to normal weight children.

METHODS

We measured inhibitory control functions in 93 otherwise healthy overweight/obese and 92 normal weight 10-year-old children using the Stroop test and the Go/No-Go task. Event-related potentials were recorded during the Go/No-Go task.

RESULTS

Overweight/obese children showed slower reaction times (1248.6 ms (95% confidence interval (CI): 1182.9-1314.3) vs 1149.0 ms (95% CI: 1083.0-1215.1)) on the Stroop test, higher reaction time variability (0.25 (95% CI: 0.22-0.27) vs 0.21 (95% CI: 0.19-0.24)) on the Go/No-Go task and decreased P300 amplitude (4.1 μV (95% CI: 3.0-5.2) vs 6.4 μV (95% CI: 5.2-7.6)) on event-related potentials compared with normal weight children.

CONCLUSIONS

Our results indicate altered inhibitory control functions in otherwise healthy overweight/obese children, which might contribute to their excessive food consumption.

Iron supplementation in infancy contributes to more adaptive behavior at 10 years of age

Most studies of behavioral/developmental effects of iron deficiency anemia (IDA) or iron supplementation in infancy have found social-emotional differences. Differences could relate to behavioral inhibition or lack of positive affect and altered response to reward. To determine long-term behavioral effects, the study was a follow-up of a randomized controlled trial of behavioral/developmental effects of preventing IDA in infancy. Healthy Chilean infants free of IDA at age 6 mo were randomly assigned to iron supplementation or no added iron (formula with iron/powdered cow milk, vitamins with/without iron) from ages 6 to 12 mo. At age 10 y, 59% (666 of 1123) and 68% (366 of 534) of iron-supplemented and no-added-iron groups were assessed. Social-emotional outcomes included maternal-reported behavior problems, self-reported behavior, examiner ratings, and video coding of a social stress task and gamelike paradigms. Examiners rated the iron-supplemented group as more cooperative, confident, persistent after failure, coordinated, and direct and reality-oriented in speech and working harder after praise compared with the no-added-iron group. In a task designed to elicit positive affect, supplemented children spent more time laughing and smiling together with their mothers and started smiling more quickly. In the social stress task they smiled and laughed more and needed less prompting to complete the task. All P values were <0.05; effect sizes were 0.14-0.36. There were no differences in behaviors related to behavioral inhibition, such as anxiety/depression or social problems. In sum, iron supplementation in infancy was associated with more adaptive behavior at age 10 y, especially in affect and response to reward, which may improve performance at school and work, mental health, and personal relationships.

Long-term neuroendocrine effects of iron-deficiency anemia in infancy

INTRODUCTION

Iron-deficiency anemia (IDA) is recognized to have long-lasting effects on neurodevelopment, but there is little research on neuroendocrine systems.

METHODS

This study examined the effects of IDA in early or later infancy on plasma cortisol and prolactin stress-response patterns for 1 h after a venipuncture and catheter placement in 10-y-old healthy Chilean children. Children identified with IDA at 6 mo (IDA-6; n = 13) or 12 mo (IDA-12; n = 24) and who were iron sufficient (IS) at other infancy time points were compared to children who were IS at all time points during infancy (n = 23). All children received at least 6 mo of oral iron treatment in infancy.

RESULTS

At 10 y of age, IDA-6 and IDA-12 children demonstrated altered cortisol response patterns; both showed a more immediate decline and IDA-12 children showed a blunted curvature as compared to IS children. IDA-12 children showed significantly lower cortisol levels at 30 and 45 min after venipuncture and catheter placement than did IS children. There were no significant differences for stress-responsive plasma prolactin patterns between groups.

DISCUSSION

The results indicate that having IDA during infancy is associated with long-term neuroendocrine effects on stress-responsive cortisol patterns.

Iron-fortified vs low-iron infant formula: developmental outcome at 10 years

OBJECTIVE

To assess long-term developmental outcome in children who received iron-fortified or low-iron formula.

DESIGN

Follow-up at 10 years of a randomized controlled trial (1991-1994) of 2 levels of formula iron. Examiners were masked to group assignment.

SETTING

Urban areas around Santiago, Chile.

PARTICIPANTS

The original study enrolled healthy, full-term infants in community clinics; 835 completed the trial. At 10 years, 473 were assessed (56.6%).

INTERVENTION

Iron-fortified (mean, 12.7 mg/L) or low-iron (mean, 2.3 mg/L) formula from 6 to 12 months.

MAIN OUTCOME MEASURES

We measured IQ, spatial memory, arithmetic achievement, visual-motor integration, visual perception, and motor functioning. We used covaried regression to compare iron-fortified and low-iron groups and considered hemoglobin level before randomization and sensitivity analyses to identify 6-month hemoglobin levels at which groups diverged in outcome.

RESULTS

Compared with the low-iron group, the iron-fortified group scored lower on every 10-year outcome (significant for spatial memory and visual-motor integration; suggestive for IQ, arithmetic achievement, visual perception, and motor coordination; 1.4-4.6 points lower; effect sizes, 0.13-0.21). Children with high 6-month hemoglobin levels (> 12.8 g/dL [to convert to grams per liter, multiply by 10]) showed poorer outcome on these measures if they received iron-fortified formula (10.7-19.3 points lower; large effect sizes, 0.85-1.36); those with low hemoglobin levels (< 10.5 g/dL) showed better outcome (2.6-4.5 points higher; small but significant effects, 0.22-0.36). High hemoglobin levels represented 5.5% of the sample (n = 26) and low hemoglobin levels represented 18.4% (n = 87).

CONCLUSION

Long-term development may be adversely affected in infants with high hemoglobin levels who receive 12.7 mg/L of iron-fortified formula. Optimal amounts of iron in infant formula warrant further study.

Sleep alterations and iron deficiency anemia in infancy

Iron deficiency anemia (IDA) continues to be the most common single nutrient deficiency in the world. An estimated 20-25% of the world's infants have IDA, with at least as many having iron deficiency without anemia. Infants are at particular risk due to rapid growth and limited dietary sources of iron. We found that infants with IDA showed different motor activity patterning in all sleep-waking states and several differences in sleep states organization. Sleep alterations were still apparent years after correction of anemia with iron treatment in the absence of subsequent IDA. We suggest that altered sleep patterns may represent an underlying mechanism that interferes with optimal brain functioning during sleep and wakefulness in former IDA children.

Home intervention improves cognitive and social-emotional scores in iron-deficient anemic infants

BACKGROUND

Iron-deficiency anemia (IDA) is associated with alterations in infant behavior and development that may not be corrected with iron therapy.

OBJECTIVE

To determine if a home-based intervention to foster child development improves behavior and development of infants with IDA.

METHODS

Infants with IDA and nonanemic infants aged 6 and 12 months were treated with oral iron and randomly assigned to a year of surveillance or intervention. Infants in the surveillance group were visited weekly, and information on iron intake, feeding, and health were recorded. Infants in the intervention were visited weekly, and the home visits included an hour-long program to foster child development by providing support to the mother-infant relationship. The number of infants enrolled was 128 (66 who received intervention) and 149 (70 intervention) at 6 and 12 months, respectively. Psychologists who were unaware of iron status and intervention assignment assessed infants' cognitive, motor, and social-emotional development (Bayley Scales) at the beginning, midpoint, and end of the year; 116 6-month-olds and 134 12-month-olds had at least 2 assessments. Hierarchical linear modeling was used to analyze change over time.

RESULTS

Infants with IDA, regardless of enrollment age, were rated as less positive in social-emotional behavior at baseline. There were significant interactions between iron status and intervention associated with change in cognitive performance and positive social-emotional behavior. Infants with IDA who received intervention had developmental trajectories comparable to those of nonanemic infants in the intervention and surveillance groups, but these infants did not catch up in social-emotional behavior. Infants with IDA who received surveillance showed less increase in cognitive scores and had declines in positive social-emotional ratings.

CONCLUSIONS

Home-based intervention to foster child development improved cognitive and social-emotional scores in infants with IDA, but social-emotional differences remained between infants with IDA and those without IDA.

Sleep disturbances and serum ferritin levels in children with attention-deficit/hyperactivity disorder

BACKGROUND

A subset of children with attention-deficit/hyperactivity disorder (ADHD) may present with impairing sleep disturbances. While preliminary evidence suggests that iron deficiency might be involved into the pathophysiology of daytime ADHD symptoms, no research has been conducted to explore the relationship between iron deficiency and sleep disturbances in patients with ADHD. The aim of this study was to assess the association between serum ferritin levels and parent reports of sleep disturbances in a sample of children with ADHD.

SUBJECTS

Sixty-eight consecutively referred children (6-14 years) with ADHD diagnosed according to DSM-IV criteria using the semi-structured interview Kiddie-SADS-PL.

MEASURES

parents filled out the Sleep Disturbance Scale for Children (SDSC) and the Conners Parent Rating Scale (CPRS). Serum ferritin levels were determined using the Tinaquant method.

RESULTS

Compared to children with serum ferritin levels >or=45 microg/l, those with serum ferritin levels <45 microg/l had significantly higher scores on the SDSC subscale "Sleep wake transition disorders" (SWTD) (P = 0.042), which includes items on abnormal movements in sleep, as well as significantly higher scores on the CPRS-ADHD index (P = 0.034). The mean scores on the other SDSC subscales did not significantly differ between children with serum ferritin >or=45 and <45 microg/l. Serum ferritin levels were inversely correlated to SWTD scores (P = 0.043).

CONCLUSION

Serum ferritin levels <45 microg/l might indicate a risk for sleep wake transition disorders, including abnormal sleep movements, in children with ADHD. Our results based on questionnaires set the basis for further actigraphic and polysomnographic studies on nighttime activity and iron deficiency in ADHD. Research in this field may suggest future trials of iron supplementation (possibly in association with ADHD medications) for abnormal sleep motor activity in children with ADHD.

Sleep and neurofunctions throughout child development: lasting effects of early iron deficiency

Iron-deficiency anemia (IDA) continues to be the most common single nutrient deficiency in the world. Infants are at particular risk due to rapid growth and limited dietary sources of iron. An estimated 20% to 25% of the world's infants have IDA, with at least as many having iron deficiency without anemia. High prevalence is found primarily in developing countries, but also among poor, minority, and immigrant groups in developed ones. Infants with IDA test lower in mental and motor development assessments and show affective differences. After iron therapy, follow-up studies point to long-lasting differences in several domains. Neurofunctional studies showed slower neural transmission in the auditory system despite 1 year of iron therapy in IDA infants; they still had slower transmission in both the auditory and visual systems at preschool age. Different motor activity patterning in all sleep-waking states and several differences in sleep states organization were reported. Persistent sleep and neurofunctional effects could contribute to reduced potential for optimal behavioral and cognitive outcomes in children with a history of IDA.

Delayed CNS maturation in iron-deficient anaemic infants

Direct evidence of CNS developmental alterations in iron-deficient anaemic (IDA) infants was obtained. Twenty 3-15-month-old IDA and 20 non-IDA infants (age and gender matched), healthy in every other respect, were studied. Complete blood and iron kinetics tests determined an IDA status. Psychomotor development was assessed through the test of Rogers and co-workers [Rogers SJ, Donovan CM, D'Eugenio D, Brown SL, Whiteside E, Moersch MS, Schafer DS. (eds) Developmental Programming for Infants and Young Children, Vol 2. University of Michigan Press, 1981] and under the 10-20 International System qEEG was performed (sleep/stage II). A Pearson's correlation test was applied between haematological, psychomotor and broad band EEG variables, and through ANOVA psychomotor and AP means were compared. IDA infants showed lower scores in cognition, fine motor and social/emotional areas, higher delta/theta and lower alpha power. Most correlations between haematological/psychological variables were positive. Delta/theta correlations were negative with self-care/gross and motor items while alpha/beta AP showed positive correlations with psychomotor and haematological variables. A clear association was found between EEG alterations and a low haematological/iron profile leading to a delayed psychomotor development.