Iron deficiency decreases dopamine D1 and D2 receptors in rat brain

Iron and n-3 fatty acid depletion, alone and in combination, during early development provoke neurochemical changes, anhedonia, anxiety and social dysfunction in rats

Objectives: Both iron and omega-3 (n-3) fatty acids (FA) play important roles in the development and functioning of the brain. We investigated the effects of n-3 FA and iron deficiencies, alone and in combination, during early development on behaviour and brain monoamines in rats. Methods: Using a 2-factorial design, female Wistar rats were randomly allocated to one of four diet groups: Control, n-3 FA deficient (n-3 FAD), iron deficient (ID), or n-3 FAD + ID. Females received these diets throughout mating, pregnancy and lactation. Offspring (n = 24/group; male:female = 1:1) continued on the same diet until post-natal day 42-45, and underwent a sucrose preference test (SPT), novel object recognition test, elevated plus maze (EPM) and social interaction test (SIT). Results: ID offspring consumed less sucrose in the SPT and spent more time in closed arms and less time in open arms of the EPM than non-ID offspring. In female offspring only, ID and n-3 FAD reduced time approaching and together in the SIT, with an additive effect of ID and n-3 FAD for even less time approaching and spent together in the n-3 FAD + ID group compared to controls. ID offspring had higher striatal dopamine and norepinephrine and lower frontal cortex dopamine concentrations. N-3 FAD and ID affected frontal cortex serotonin concentrations in a sex-specific manner. Conclusions: Our results suggest that ID and n-3 FAD during early development provoke anhedonia, anxiety and social dysfunction in rats, with potential additive and attenuating effects when combined. These effects may in part be attributed to disturbances in brain neurochemistry and may be sex-specific.

Vitamins, minerals and their maternal levels' role in brain development: An updated literature-review

One's neurobehavioural and mental health are built during the exact and complex process of brain development. It is thought that fetal development is where neuropsychiatric disorders first emerged. Behavioural patterns can change as a result of neuropsychiatric illnesses. The incidence is rising quickly; nevertheless, providing exceptional care remains a significant challenge for families and healthcare systems. It has been demonstrated that one of the main factors causing the transmission of these diseases is maternal exposure. Through physiologic pathways, maternal health and intrauterine exposures can affect brain development. Our attention has been focused on epigenetic factors, particularly in the gestational environment, which may be responsible for human neurodegenerative diseases since our main mental development occurs during the nine months of intrauterine life. After thoroughly searching numerous databases, this study examined the effect of fat-soluble vitamins, water-soluble vitamins, and minerals and their maternal-level effect on brain development.

The influence of depression on clinical outcomes of total shoulder arthroplasty: a systematic Review

PURPOSE

Much of the current literature on total shoulder arthroplasty (TSA) has assessed the impact of preoperative medical comorbidities on postoperative clinical outcomes. The literature concerning the impact of psychological disorders such as depression on TSA has increased in popularity in recent years, but there lacks a thorough review of the influence of depression on postoperative pain and functional outcomes.

METHODS

We queried PubMed/MEDLINE and identified six clinical studies that evaluated the influence of a psychiatric diagnosis of depression on patient outcomes after TSA. Studies that discussed the impacts of depression on TSA, including PROs or adverse events in adults, were included. Studies focused on other psychologic pathology, non-TSA shoulder treatments, or TSA not for primary osteoarthritis were excluded. Non-clinical studies, systematic reviews, letters to the editor, commentaries, dissertations, books, and book chapters were excluded.

RESULTS

Three cohort studies described patient-reported pain and functional outcomes and three database studies assessed the risk of postoperative complications. Cohort studies demonstrated that the prevalence of depression in patients undergoing TSA decreased from preoperatively to 12-months postoperatively. Two studies demonstrated that depression is an independent predictor of less pre- to postoperative improvement in the ASES score at minimum 2-year follow-up; however, one study found the difference between patients with and without depression did not exceed the minimum clinically important difference. Database studies demonstrated that depression was associated with higher rates of blood transfusion (n = 1, OR = 1.8), anemia (n = 1, OR = 1.65), wound infection (n = 2, OR = 1.41-2.09), prosthetic revision (n = 1, OR = 1.92), and length of hospital stay (n = 3, LOS = 2.5-3 days).

CONCLUSION

Although patients with a preoperative diagnosis of depression undergoing TSA can achieve satisfactory relief of shoulder pain and restoration of function, they may experience poorer patient-reported outcomes and a higher risk of postoperative adverse events compared to their peers. Surgeons should be cognizant of the influence of depression in their patients to facilitate proper patient selection that maximizes patient satisfaction, function, and minimizes the risk of adverse events following TSA.

LEVEL OF EVIDENCE

Level IV.

Iron imbalance in neurodegeneration

Iron is an essential element for the development and functionality of the brain, and anomalies in its distribution and concentration in brain tissue have been found to be associated with the most frequent neurodegenerative diseases. When magnetic resonance techniques allowed iron quantification in vivo, it was confirmed that the alteration of brain iron homeostasis is a common feature of many neurodegenerative diseases. However, whether iron is the main actor in the neurodegenerative process, or its alteration is a consequence of the degenerative process is still an open question. Because the different iron-related pathogenic mechanisms are specific for distinctive diseases, identifying the molecular mechanisms common to the various pathologies could represent a way to clarify this complex topic. Indeed, both iron overload and iron deficiency have profound consequences on cellular functioning, and both contribute to neuronal death processes in different manners, such as promoting oxidative damage, a loss of membrane integrity, a loss of proteostasis, and mitochondrial dysfunction. In this review, with the attempt to elucidate the consequences of iron dyshomeostasis for brain health, we summarize the main pathological molecular mechanisms that couple iron and neuronal death.

Celiac disease and depressive disorders as nutritional implications related to common factors - A comprehensive review

Celiac disease (CD) is an immune-mediated disease affecting the small intestine. The only treatment strategy for CD is the gluten-free diet (GFD). One of the more common mental disorders in CD patients is major depressive disorder (MDD). The influence of GFD on the occurrence of MDD symptoms in patients with CD will be evaluated. This diet often reduces nutritional deficiencies in these patients and also helps to reduce depressive symptoms. Both disease entities are often dominated by the same deficiencies of nutrients such as iron, zinc, selenium, iodine, or B and D vitamins. Deficiencies of particular components in CD can favor MDD and vice versa. Gluten can adversely affect the mental state of patients without CD. Also, intestinal microbiota may play an important role in the described process. This work aims to comprehensively assess the common factors involved in the pathomechanisms of MDD and CD, with particular emphasis on nutrient imbalances. Given the complexity of both disease entities, and the many common links, more research related to improving mental health in these patients and the implementation of a GFD would need to be conducted, but it appears to be a viable pathway to improving the quality of life and health of people struggling with CD and MDD. Therefore, probiotics, micronutrients, macronutrients, and vitamin supplements are recommended to reduce the risk of MDD, given that they may alleviate the symptoms of both these disease entities. In turn, in patients with MDD, it is worth considering testing for CD.

Alterations in subcortical magnetic susceptibility and disease-specific relationship with brain volume in major depressive disorder and schizophrenia

Quantitative susceptibility mapping is a magnetic resonance imaging technique that measures brain tissues' magnetic susceptibility, including iron deposition and myelination. This study examines the relationship between subcortical volume and magnetic susceptibility and determines specific differences in these measures among patients with major depressive disorder (MDD), patients with schizophrenia, and healthy controls (HCs). This was a cross-sectional study. Sex- and age- matched patients with MDD (n = 49), patients with schizophrenia (n = 24), and HCs (n = 50) were included. Magnetic resonance imaging was conducted using quantitative susceptibility mapping and T1-weighted imaging to measure subcortical susceptibility and volume. The acquired brain measurements were compared among groups using analyses of variance and post hoc comparisons. Finally, a general linear model examined the susceptibility-volume relationship. Significant group-level differences were found in the magnetic susceptibility of the nucleus accumbens and amygdala (p = 0.045). Post-hoc analyses indicated that the magnetic susceptibility of the nucleus accumbens and amygdala for the MDD group was significantly higher than that for the HC group (p = 0.0054, p = 0.0065, respectively). However, no significant differences in subcortical volume were found between the groups. The general linear model indicated a significant interaction between group and volume for the nucleus accumbens in MDD group but not schizophrenia or HC groups. This study showed susceptibility alterations in the nucleus accumbens and amygdala in MDD patients. A significant relationship was observed between subcortical susceptibility and volume in the MDD group's nucleus accumbens, which indicated abnormalities in myelination and the dopaminergic system related to iron deposition.

A comprehensive update on the ADMET considerations for α2δ calcium channel ligand medications for treating restless legs syndrome

INTRODUCTION

Restless legs syndrome/Willis-Ekbom disease (RLS/WED) is a sleep-related sensory-motor disorder associated with poor sleep quality and impaired daily functioning. In patients affected by chronic RLS/WED, a pharmacological therapy is recommended. International guidelines suggest to start the treatment with a α2δ calcium channel ligand in most cases, unless contraindicated.

AREAS COVERED

The present review is based on an extensive Internet and PubMed search from 1986 to 2024. Our purpose is to describe the absorption, distribution, metabolism, and toxicology (ADMET) of the α2δ ligands, with common consideration for the therapeutic class, specificities of different compounds, efficacy, and safety in relation to other treatment options.

EXPERT OPINION

α2δ ligands are quite similar in their ADMET profiles, sharing most of the pharmacokinetics and potential adverse effects. However, we highlight the linear kinetic of gabapentin enacarbil and pregabalin, differently from gabapentin. α2δ ligands are safe and effective for the treatment of RLS/WED. Additional benefits can be obtained in comorbid insomnia, chronic pain syndromes, history of impulse control disorder, and comorbid anxiety. The use of α2δ ligands is associated with poor risk of augmentation. We still need new long-term safe and effective treatments, which could be developed along with our knowledge of RLS/WED pathophysiology.

Serum binding folate receptor autoantibodies lower in autistic boys and positively-correlated with folate

Folate receptor autoantibody (FRAA) has caught increasing attention since its discovery in biological fluids of patients with autism spectrum disorder (ASD), but quantification and understanding of its function are still in their infancy. In this study, we aimed to quantify serum binding-FRAA and explore its relation with serum folate, vitamin B12 (VB12) and ferritin. We quantitated serum binding-FRAA in 132 ASD children and 132 typically-developing (TD) children, as well as serum levels of folate, VB12 and ferritin. The results showed that serum binding-FRAA in the ASD group was significantly lower than that in the TD group (p < 0.0001). Further analysis showed that the difference between these two groups was attributed to boys in each group, not girls. There was no statistically significant difference in folate levels between the ASD and TD groups (p > 0.05). However, there was significant difference in boys between these two groups, not girls. Additionally, the combination of nitrite and binding-FRAA showed potential diagnostic value in patients with ASD (AUC > 0.7). Moreover, in the ASD group, the level of folate was consistent with that of binding-FRAA, whereas in the TD group, the binding-FRAA level was high when the folate level was low. Altogether, these differences revealed that the low serum FRAA in autistic children was mediated by multiple factors, which deserves more comprehensive investigation with larger population and mechanistic studies.

Assessing the pattern electroretinogram as a proxy measure for dopamine in the context of iron deficiency

OBJECTIVES

Animal studies have suggested that dietary iron deficiency (ID) negatively affects dopamine (DA) synthesis and re-uptake, which in turn negatively affects memory and cognition. This study was intended to assess whether the pattern electroretinogram (pattern ERG) could be used as an indirect measure of DA in college-age women with and without ID by determining the extent to which features of the ERG were sensitive to iron status and were related to other indirect measures of DA.

METHODS

The pattern ERG was measured in 21 iron deficient non-anemic (IDNA) and 21 iron sufficient (IS) women, who also performed a contrast detection and probabilistic selection task, both with concurrent electroencephalography (EEG). Both spontaneous and task-related blink rates were also measured.

RESULTS

The implicit times of the A- and B-waves were significantly longer for the IDNA than for the IS women. Both the amplitudes and implicit times of the A- and B-waves were significantly correlated with levels of serum ferritin (sFt). Only the amplitude of the A-wave was correlated with spontaneous blink rate. It was possible to accurately identify a woman's iron status solely on the basis of the implicit time of the B-wave. Finally, the implicit times of the ERG features mediated the relationship between iron levels and accuracy in the probabilistic selection task.

CONCLUSIONS

Results suggest the utility of the pattern ERG in testing the hypothesis that iron deficiency affects DA levels in humans and that this may be one of the mechanisms by which iron deficiency negatively affects cognition.

The iron-dopamine D1 coupling modulates neural signatures of working memory across adult lifespan

Brain iron overload and decreased integrity of the dopaminergic system have been independently reported as brain substrates of cognitive decline in aging. Dopamine (DA), and iron are co-localized in high concentrations in the striatum and prefrontal cortex (PFC), but follow opposing age-related trajectories across the lifespan. DA contributes to cellular iron homeostasis and the activation of D1-like DA receptors (D1DR) alleviates oxidative stress-induced inflammatory responses, suggesting a mutual interaction between these two fundamental components. Still, a direct in-vivo study testing the iron-D1DR relationship and their interactions on brain function and cognition across the lifespan is rare. Using PET and MRI data from the DyNAMiC study (n=180, age=20-79, %50 female), we showed that elevated iron content was related to lower D1DRs in DLPFC, but not in striatum, suggesting that dopamine-rich regions are less susceptible to elevated iron. Critically, older individuals with elevated iron and lower D1DR exhibited less frontoparietal activations during the most demanding task, which in turn was related to poorer working-memory performance. Together, our findings suggest that the combination of elevated iron load and reduced D1DR contribute to disturbed PFC-related circuits in older age, and thus may be targeted as two modifiable factors for future intervention.

Iron deficiency and sexual dysfunction in women

INTRODUCTION

Sexual dysfunction negatively affects approximately 40% to 50% of adult women across various stages of life. Common risk factors include sexual traumas, relationship problems, chronic conditions, medication side effects, and poor physical health, including iron deficiency.

OBJECTIVES

This review summarizes a presentation from a symposium that discussed the types and causes of sexual dysfunction at key times in women's lives, focusing on the relationship between iron deficiency and sexual dysfunction.

METHODS

The symposium was held at the XV Annual European Urogynaecological Association Congress, Antibes, France, in October 2022. Symposium content was identified through literature searches of PubMed. Original research, review articles, and Cochrane analyses discussing sexual dysfunction in association with iron deficiency/anemia were included.

RESULTS

Iron deficiency in women is commonly caused by abnormal uterine bleeding, but women may develop iron deficiency anemia (IDA) because of increased iron needs or reduced iron intake/absorption. Treatment with oral iron supplementation has been shown to improve sexual function in women with IDA. Ferrous sulphate is considered as a standard of care for oral iron treatment; prolonged-release iron formulations have improved tolerability, enabling lower doses and better tolerability.

CONCLUSION

IDA and sexual dysfunction are related, so the identification of sexual dysfunction or iron deficiency in a woman should prompt an investigation of the other condition. Testing for iron deficiency is an inexpensive and simple step that can be routinely included in the workup of women with sexual dysfunction. Once identified, IDA and sexual dysfunction in women should be treated and followed to optimize quality of life.

Association between iron deficiency anemia and sleep duration in the first year of life

OBJECTIVE

The aim of this study was to investigate the association between iron deficiency anemia and sleep duration in the first year of life.

METHODS

A total of 123 infants were investigated, with sleep being evaluated at 3, 6, and 12 months of age and anemia at birth and 6 months. The cutoff points for anemia and short sleep duration were hemoglobin <11 g/dL (at birth and/or 6 months) and <10 h (at 3, 6, and 12 months), respectively. The comparison of the average sleep time between infants with and without anemia was performed using the Student's t-test, and logistic regression models were also used to verify differences in the sleep duration (short/not short) between the groups. Linear regression analyses were conducted to determine the association between sleep duration and hemoglobin values. The analyses were adjusted for potential confounders.

RESULTS

Children with anemia were more likely to be short sleepers [odds ratio (95% confidence interval (CI)): 4.02 (1.02-15.76); p≤0.05], and for each unit increase in hemoglobin values, the sleep duration increased by 16.2 min [β (95%CI): 0.27 (0.00-0.55); p≤0.05), regardless of family income, maternal schooling, gender, and body mass index at birth.

CONCLUSIONS

Our results suggest that iron deficiency anemia is associated with short sleep duration in the first year of life and indicate the need for longitudinal investigations, with longer follow-up, to verify the impact of anemia on sleep duration at subsequent ages.

Iron deficiency and cognitive functioning in kidney transplant recipients: findings of the TransplantLines biobank and cohort study

BACKGROUND

Neurocognitive impairment is common in kidney transplant recipients (KTRs). Adequate brain functioning requires energy and neurotransmitter activity, for which iron is essential. We aimed to investigate iron deficiency (ID) as a potentially modifiable risk factor for cognitive impairment in KTRs.

METHODS

We analyzed stable KTRs participating in the TransplantLines Biobank and Cohort study. Participants underwent neuropsychological tests for memory, mental speed, and attention and executive functioning. ID was defined as ferritin <100 µg/mL or 100-299 µg/mL with transferrin saturation (TSAT) ≤20%. Associations between iron status and norm scores of neurocognitive outcomes, corrected for age, sex and education, were assessed using multivariable linear regression analyses adjusted for potential confounders including hemoglobin.

RESULTS

We included 166 KTRs [median (IQR) age 57 (45-65) years, 59% male, estimated glomerular filtration rate 51±18 mL/min/1.73 m2]. Time since transplantation was 5.8 (1.0-12.0) years. Prevalence of ID was 65%. ID was independently associated with lower scores for mental speed (std.β = -0.19, P = .02) and attention and executive functioning (std.β = -0.19, P = .02), and tended to be associated with worse memory (std.β = -0.16, P = .07). Lower plasma ferritin levels were associated with worse memory (std.β = 0.23, P = .007), mental speed (std.β = 0.34, P < .001), and attention and executive functioning (std.β = 0.30, P = .001). Lower TSAT was associated with worse memory (std.β = 0.19, P = .04) and mental speed (std.β = 0.27, P = .003), and tended to be associated with worse attention and executive functioning (std.β = 0.16, P = .08).

CONCLUSIONS

Iron-deficient KTRs performed worse on neurocognitive tasks measuring memory, mental speed, and attention and executive functioning. These findings set the stage for prospective studies addressing whether ID correction restores cognitive function after kidney transplantation.

Iron deficiency and internalizing symptom severity in unmedicated adolescents: a pilot study

BACKGROUND

Iron plays a key role in a broad set of metabolic processes. Iron deficiency is the most common nutritional deficiency in the world, but its neuropsychiatric implications in adolescents have not been examined.

METHODS

Twelve- to 17-year-old unmedicated females with major depressive or anxiety disorders or with no psychopathology underwent a comprehensive psychiatric assessment for this pilot study. A T1-weighted magnetic resonance imaging scan was obtained, segmented using Freesurfer. Serum ferritin concentration (sF) was measured. Correlational analyses examined the association between body iron stores, psychiatric symptom severity, and basal ganglia volumes, accounting for confounding variables.

RESULTS

Forty females were enrolled, 73% having a major depressive and/or anxiety disorder, 35% with sF < 15 ng/mL, and 50% with sF < 20 ng/mL. Serum ferritin was inversely correlated with both anxiety and depressive symptom severity (r = -0.34, p < 0.04 and r = -0.30, p < 0.06, respectively). Participants with sF < 15 ng/mL exhibited more severe depressive and anxiety symptoms as did those with sF < 20 ng/mL. Moreover, after adjusting for age and total intracranial volume, sF was inversely associated with left caudate (Spearman's r = -0.46, p < 0.04), left putamen (r = -0.58, p < 0.005), and right putamen (r = -0.53, p < 0.01) volume.

CONCLUSIONS

Brain iron may become depleted at a sF concentration higher than the established threshold to diagnose iron deficiency (i.e. 15 ng/mL), potentially disrupting brain maturation and contributing to the emergence of internalizing disorders in adolescents.

Attention deficit hyperactivity disorder and restless leg syndrome across the lifespan: A systematic review and meta-analysis

This systematic review aims to assess the association between attention deficit hyperactivity disorder (ADHD) and restless legs syndrome (RLS) in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Databases were searched for original articles that reported prevalence data on ADHD and RLS until January 24th, 2023. Two independent reviewers evaluated the quality of the articles using the National Institutes of Health assessment tool. Among the 208 articles identified between 1996 and 2022, 29 were included. In large general population studies, 2.6-15.3% of participants met the RLS criteria, of which 3.2-17.4% presented with ADHD. In the ADHD group, RLS symptoms ranged from 11 to 42.9% in children and 20-33.0% in adults. This suggests a strong co-occurrence between RLS and ADHD. A common characteristic of these conditions is sleep fragmentation, as discussed in the reviewed papers. Although large-scale studies with comparable diagnostic criteria across the lifespan are required, our findings may advocate a possible common physiological pathway, including sleep fragmentation and dopaminergic system impairment.

Putative Animal Models of Restless Legs Syndrome: A Systematic Review and Evaluation of Their Face and Construct Validity

Restless legs syndrome (RLS) is a sensorimotor disorder that severely affects sleep. It is characterized by an urge to move the legs, which is often accompanied by periodic limb movements during sleep. RLS has a high prevalence in the population and is usually a life-long condition. While its origins remain unclear, RLS is initially highly responsive to treatment with dopaminergic agonists that target D2-like receptors, in particular D2 and D3, but the long-term response is often unsatisfactory. Over the years, several putative animal models for RLS have been developed, mainly based on the epidemiological and neurochemical link with iron deficiency, treatment efficacy of D2-like dopaminergic agonists, or genome-wide association studies that identified risk factors in the patient population. Here, we present the first systematic review of putative animal models of RLS, provide information about their face and construct validity, and report their role in deciphering the underlying pathophysiological mechanisms that may cause or contribute to RLS. We propose that identifying the causal links between genetic risk factors, altered organ functions, and changes to molecular pathways in neural circuitry will eventually lead to more effective new treatment options that bypass the side effects of the currently used therapeutics in RLS, especially for long-term therapy.

Decreased basal ganglia and thalamic iron in early psychotic spectrum disorders are associated with increased psychotic and schizotypal symptoms

Iron deficits have been reported as a risk factor for psychotic spectrum disorders (PSD). However, examinations of brain iron in PSD remain limited. The current study employed quantitative MRI to examine iron content in several iron-rich subcortical structures in 49 young adult individuals with PSD (15 schizophrenia, 17 schizoaffective disorder, and 17 bipolar disorder with psychotic features) compared with 35 age-matched healthy controls (HC). A parametric approach based on a two-pool magnetization transfer model was applied to estimate longitudinal relaxation rate (R₁), which reflects both iron and myelin, and macromolecular proton fraction (MPF), which is specific to myelin. To describe iron content, a synthetic effective transverse relaxation rate (R₂*) was modeled using a linear fitting of R₁ and MPF. PSD patients compared to HC showed significantly reduced R₁ and synthetic R₂* across examined regions including the pallidum, ventral diencephalon, thalamus, and putamen areas. This finding was primarily driven by decreases in the subgroup with schizophrenia, followed by schizoaffective disorder. No significant group differences were noted for MPF between PSD and HC while for regional volume, significant reductions in patients were only observed in bilateral caudate, suggesting that R₁ and synthetic R₂* reductions in schizophrenia and schizoaffective patients likely reflect iron deficits that either occur independently or precede structural and myelin changes. Subcortical R₁ and synthetic R₂* were also found to be inversely related to positive symptoms within the PSD group and to schizotypal traits across the whole sample. These findings that decreased iron in subcortical regions are associated with PSD risk and symptomatology suggest that brain iron deficiencies may play a role in PSD pathology and warrant further study.

Perinatal iron deficiency as an early risk factor for schizophrenia

Growing evidence indicates that a suboptimal intrauterine environment confers risk for schizophrenia. The developmental model of schizophrenia posits that aberrant brain growth during early brain development and adolescence may interact to contribute to this psychiatric disease in adulthood. Although a variety of factors may perturb the environment of the developing fetus and predispose for schizophrenia later, a common mechanism has yet to be elucidated. Micronutrient deficiencies during the perinatal period are known to induce potent effects on brain development by altering neurodevelopmental processes. Iron is an important candidate nutrient to consider because of its role in energy metabolism, monoamine synthesis, synaptogenesis, myelination, and the high prevalence of iron deficiency (ID) in the mother-infant dyad. Understanding the current state of science regarding perinatal ID as an early risk factor for schizophrenia is imperative to inform empirical work investigating the etiology of schizophrenia and develop prevention and intervention programs. In this narrative review, we focus on perinatal ID as a common mechanism underlying the fetal programming of schizophrenia. First, we review the neural aberrations associated with perinatal ID that indicate risk for schizophrenia in adulthood, including disruptions in dopaminergic neurotransmission, hippocampal-dependent learning and memory, and sensorimotor gating. Second, we review the pathophysiology of perinatal ID as a function of maternal ID during pregnancy and use epidemiological and cohort studies to link perinatal ID with risk of schizophrenia. Finally, we review potential confounding phenotypes, including nonanemic causes of perinatal brain ID and future risk of schizophrenia.

Modeling relationships between iron status, behavior, and brain electrophysiology: evidence from a randomized study involving a biofortified grain in Indian adolescents

Background

Iron deficiency (ID) and iron deficiency anemia (IDA) are highly-prevalent nutrient deficiencies and have been shown to have a range of negative effects on cognition and brain function. Human intervention studies including measures at three levels—blood, brain, and behavior—are rare and our objective was to model the relationships among measures at these three levels in school-going Indian adolescents.

Methods

Male and female adolescents in rural India were screened for ID/IDA. Subjects consumed 2 meals/day for 6 months; half were randomly assigned to consume meals made from a standard grain (pearl millet) and half consumed meals made from an iron biofortified pearl millet (BPM). Prior to and then at the conclusion of the feeding trial, they completed a set of cognitive tests with concurrent electroencephalography (EEG).

Results

Overall, serum ferritin (sFt) levels improved over the course of the study. Ten of 21 possible measures of cognition showed improvements from baseline (BL) to endline (EL) that were larger for those consuming BPM than for those consuming the comparison pearl millet (CPM). Critically, the best model for the relationship between change in iron status and change in cognition had change in brain measures as a mediating factor, with both change in serum ferritin as a primary predictor and change in hemoglobin as a moderator.

Conclusions

A dietary intervention involving a biofortified staple grain was shown to be efficacious in improving blood iron biomarkers, behavioral measures of cognition, and EEG measures of brain function. Modeling the relationships among these variables strongly suggests multiple mechanisms by which blood iron level affects brain function and cognition.

Trial registration

Registered at ClinicalTrials.gov, NCT02152150, 02 June 2014.

Supplementary Information

The online version contains supplementary material available at (10.1186/s12889-022-13612-z).

Cognitive control inhibition networks in adulthood are impaired by early iron deficiency in infancy

Iron deficiency, a common form of micronutrient deficiency, primarily affects children and women. The principal cause of iron deficiency is undernutrition in low-income countries and malnutrition in middle to upper income regions. Iron is a key element for myelin production, neuronal metabolism, and dopamine functions. Iron deficiency in early life can alter brain development and exert long-lasting effects. Control inhibition is an executive function that involves several brain regions, including the prefrontal cortex and caudate and sub-thalamic nuclei. Dopamine is the prevalent neurotransmitter underlying cognitive inhibition. We followed cohort study participants who had iron deficiency anemia in infancy as well non-anemic controls. At 22 years of age, the participants were subjected to functional magnetic resonance imaging (fMRI) to evaluate the correlation between functional connectivity and performance on an inhibitory cognitive task (Go/No-Go). We hypothesized that former iron deficient anemic (FIDA) participants demonstrate less strength in functional connectivity compared with controls (C). There were not significant group differences in the behavioral results in terms of accuracy and response time. A continuous covariate interaction analysis of functional connectivity and the Go/No-Go scores demonstrated significant differences between the FIDA and C groups. The FIDA participants demonstrated less strength in connectivity in brain regions related to control inhibition, including the medial temporal lobe, impairment in the integration of the default mode network (indicating decreased attention and alertness), and an increase in connectivity in posterior brain areas, all of which suggest slower circuitry maturation. The results support the hypothesis that FIDA young adults show differences in the connectivity of networks related to executive functions. These differences could increase their vulnerability to develop cognitive dysfunctions or mental disorders in adulthood.

Iron, neuro‐bioavailability and depression

Medical management of iron deficiency (ID) requires to consider its consequences in biochemical and physiological plural functions, beyond heme/hemoglobin disrupted synthesis. Fatigue, muscle weakness, reduced exercise capacity, changes in thymia and modified emotional behaviors are the commonest symptoms integrated in the history of ID, dependent or not of the hemoglobin concentration. The relationship between depression and absolute ID (AID) is a condition which is often unrecognized. Neuro‐bioavailability and brain capture of blood iron are necessary for an appropriate synthesis of neurotransmitters (serotonin, dopamine, noradrenaline). These neurotransmitters, involved in emotional behaviors, depend on neuron aromatic hydoxylases functioning with iron as essential cofactor. Noradrenaline also has impact on neuroplasticity via brain‐derived neurotrophic factor (BDNF), which is key for prefrontal and hippocampus neurons playing a role in depression. Establishing the formal relationship between depression and AID remains difficult. Intracerebral reduced iron is still hard to quantify by neuroimaging and single‐photon emission computed tomography (SPECT) now tends to explore the neurotransmission pathways. AID has to be looked for and identified in the context of depression, major episode or resistant to conventional treatment such as serotonin reuptake inhibitor, and even in the absence of anemia, microcytosis or hypochromia (non‐anemic ID). Confronted to brain imaging, blood iron status evaluation is indicated, especially in depressed, treatment‐resistant, iron‐deficient young women. In patients suffering from depression, increase in the prevalence of AID should be considered, in order to deliver a suitable treatment, considering both anti‐depressive program and iron supplementation if AID.

Mitochondrial iron metabolism and neurodegenerative diseases

Iron is a key element for mitochondrial function and homeostasis, which is also crucial for maintaining the neuronal system, but too much iron promotes oxidative stress. A large body of evidence has indicated that abnormal iron accumulation in the brain is associated with various neurodegenerative diseases such as Huntington's disease, Alzheimer's disease, Parkinson's disease, and Friedreich's ataxia. However, it is still unclear how irregular iron status contributes to the development of neuronal disorders. Hence, the current review provides an update on the causal effects of iron overload in the development and progression of neurodegenerative diseases and discusses important roles of mitochondrial iron homeostasis in these disease conditions. Furthermore, this review discusses potential therapeutic targets for the treatments of iron overload-linked neurodegenerative diseases.

BXD Recombinant Inbred Mice as a Model to Study Neurotoxicity

BXD recombinant inbred (RI) lines represent a genetic reference population derived from a cross between C57BL/6J mice (B6) and DBA/2J mice (D2), which through meiotic recombination events possesses recombinant chromosomes containing B6 or D2 haplotype segments. The quantitative trait loci (QTLs) are the locations of segregating genetic polymorphisms and are fundamental to understanding genetic diversity in human disease susceptibility and severity. QTL mapping represents the typical approach for identifying naturally occurring polymorphisms that influence complex phenotypes. In this process, genotypic values at markers of known genomic locations are associated with phenotypic values measured in a segregating population. Indeed, BXD RI strains provide a powerful tool to study neurotoxicity induced by different substances. In this review, we describe the use of BXD RI lines to understand the underlying mechanisms of neurotoxicity in response to ethanol and cocaine, as well as metals and pesticide exposures.

Iron deficiency in pregnancy: Influence on sleep, behavior, and molecular markers of adult male offspring

Iron restriction during pregnancy can lead to iron deficiency and changes in the dopaminergic system in the adulthood of offspring, and restless legs syndrome (RLS) is closely related to these changes. Objectives: Analyze whether iron restriction during pregnancy would cause changes in the behavior, sleep, and dopaminergic system of the male offspring. In addition, we aimed to assess whether exercise would be able to modulate these variables. The pregnant rats (Wistar) were divided into four groups with different concentrations of iron in the diet: standard (St), supplementation (Su), restriction since weaning (R1), and restriction only during pregnancy (R2). After birth, the offspring were assigned to their respective groups according to the dams diet (St, Su, R1, and R2) and distributed into sedentary (SD) and exercised (EX) (for 8 weeks of training), reaching eight groups of offspring (O): OSt SD, OSt EX, OSu SD, OSu EX, OR1 SD, OR1 EX, OR2 SD, and OR2 EX. Sleep, behavior, and analysis of key genes of dopaminergic system (D2, DAT) were performed after 8 weeks. The results for trained offspring that the mother received supplementation diet were the most expressive, with increased freezing and the OR1 SD group showed an increase in DAT protein content. These changes may have been due to the association between the dams diet during pregnancy and the practice of exercise by the offspring. The different concentrations of iron during pregnancy caused changes in the offspring, however, they were not associated with fetal programming in the context of RLS.

Genetic differences in ethanol consumption: effects on iron, copper, and zinc regulation in mouse hippocampus

One common characteristic of neurodegenerative diseases is dysregulation of iron, usually with observed increases in its concentration in various regions. Heavy alcohol consumption is believed to contribute to such iron dysregulation in the brain with accompanying dementia. To examine this effect and related genetic-based individual differences in an animal model, we subjected female mice from 12 BXD recombinant inbred strains to 16 weeks of alcohol consumption using the drinking in the dark (DID) method. Daily consumption was recorded and at the end of 16 weeks hippocampus tissues harvested. Concentrations of iron, copper and zinc were measured using X-ray fluorescence technology. The results showed that, DID increased iron overall across all strains, ranging from 3 to 68%. Copper and Zinc both decreased, ranging from 0.4-42 and 5-35% respectively. Analysis of variance revealed significant strain by treatment interactions for all three metals. Additionally, in the DID group, we observed strain differences in reduction of hippocampus mass. These findings are particularly interesting to us because high alcohol consumption in humans has been associated with neurodegeneration and dementia related to disruption of iron regulation. The findings of alcohol consumption associated decreases in copper and zinc are novel. The role of copper regulation and neurological function related to alcohol consumption is as yet largely unexplored. The role of zinc is better known as a neuromodulator in the hippocampus and appears to be protective against neurological damage. It would seem then, that the alcohol-related decrease in zinc in the hippocampus would be of concern and warrants further study.

Saliva Iron Levels to Assess Iron Status in Children

BACKGROUND: Iron plays an essential role in the process of neurotransmitter synthesis and neuron myelination. Iron deficiency impacts low cognitive performance, even involved in long-term effects even though iron deficiency has been overcome. Given the impact caused by iron deficiency, it is necessary to monitor the status of iron in the body. Diagnostic tests carried out so far use blood specimens taken with invasive method. This creates fear for the child because of the pain it causes. AIM: This study aims to obtain a non-invasive alternative diagnostic test in detecting iron deficiency in children using saliva as an examination specimen. METHODS: The design of this study was case control, with a sample of elementary school children aged 9–12 years and for women who had not experienced menstruation. The sample consisted of 40 people who were taken randomly and grouped into iron deficiency and normal. Determine the group of iron deficiency and normal was based on the results of an examination of serum iron levels. Next, saliva samples were taken to determine saliva iron levels. The characteristics of the sample data were obtained through a questionnaire, while the measurement of serum iron levels was carried out by the spectrophotometric method, and the measurement of saliva iron levels was carried out by the ELISA method. Data were analyzed using Spearman’s test. RESULTS: Based on serum iron measurements, it was found that the mean serum iron levels in children with iron deficiency were lower than normal children (38.153 ± 8.99 q/dL vs. 79.198 ± 14.2219 q/dL), on the contrary, on examination of iron levels, it was found that in children with iron deficiency, saliva iron levels were higher than in normal children (5.745 ± 3.04 q/dL vs. 2,576 ± 1.43 q/dL). The correlation test results showed a significant negative correlation between serum iron levels and moderate iron levels (p = 0.000, r = –0.518). CONCLUSION: Saliva iron levels can be used as an alternative non-invasive diagnostic test to assess children’s iron status.

Brain iron assessment in patients with First-episode schizophrenia using quantitative susceptibility mapping

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Patients with first-episode schizophrenia had significantly decreased QSM values in the bilateral substantia nigra, left red nucleus and left thalamus.

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Patients with first-episode schizophrenia had significantly increased regional volumes in the bilateral putamen and bilateral substantia nigra.

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QSM provides superior sensitivity over R₂* mapping in the evaluation of schizophrenia-related iron alterations.

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QSM values in regions that showed intergroup differences did not exhibited significant correlations with PANSS scores.

Purpose

Decreased serum ferritin level was recently found in schizophrenia. Whether the brain iron concentration in schizophrenia exists abnormality is of research significance. Quantitative susceptibility mapping (QSM) was used in this study to assess brain iron changes in the grey matter nuclei of patients with first-episode schizophrenia.

Methods

The local ethics committee approved the study, and all subjects gave written informed consent. Thirty patients with first-episode schizophrenia and 30 age and gender-matched healthy controls were included in this study. QSM and effective transverse relaxation rate (R₂*) maps were reconstructed from a three-dimensional multi-echo gradient-echo sequence. The inter-group differences of regional QSM values, R₂* values and volumes were calculated in the grey matter nuclei, including bilateral caudate nucleus, putamen, globus pallidus, substantia nigra, red nucleus, and thalamus. The diagnostic performance of QSM and R₂* was evaluated using receiver operating characteristic curve. The correlations between regional iron variations and clinical PANSS (Positive and Negative Syndrome Scale) scores were assessed using partial correlation analysis.

Results

Compared to healthy controls, patients with first-episode schizophrenia had significantly decreased QSM values (less paramagnetic) in the bilateral substantia nigra, left red nucleus and left thalamus (p < 0.05, FDR correction). QSM proved more sensitive than R₂* regarding inter-group differences. The highest diagnostic performance for first-episode schizophrenia was observed in QSM value of the left substantia nigra (area under the curve, AUC = 0.718, p = 0.004). Regional volumes of bilateral putamen and bilateral substantia nigra were increased (p < 0.05, FDR correction) in first-episode schizophrenia. However, both QSM and R₂* values did not show significant correlations with PANSS scores (p > 0.05).

Conclusion

This study reveals decreased iron concentration in grey matter nuclei of patients with first-episode schizophrenia. QSM provides superior sensitivity over R₂* in the evaluation of schizophrenia-related brain iron changes. It demonstrated that QSM may be a potential biomarker for further understanding the pathophysiological mechanism of first-episode schizophrenia.

Dopamine-related striatal neurophysiology is associated with specialization of frontostriatal reward circuitry through adolescence

Characterizing developmental changes in frontostriatal circuitry is critical to understanding adolescent development and can clarify neurobiological mechanisms underlying increased reward sensitivity and risk-taking and the emergence of psychopathology during this period. However, the role of striatal neurobiology in the development of frontostriatal circuitry through human adolescence remains largely unknown. We examined background connectivity during a reward-guided decision-making task ("reward-state"), in addition to resting-state, and assessed the association between age-related changes in frontostriatal connectivity and age-related changes in reward learning and risk-taking through adolescence. Further, we examined the contribution of dopaminergic processes to changes in frontostriatal circuitry and decision-making using MR-based assessments of striatal tissue-iron as a correlate of dopamine-related neurobiology. Connectivity between the nucleus accumbens (NAcc) and ventral anterior cingulate, subgenual cingulate, and orbitofrontal cortices decreased through adolescence into adulthood, and decreases in reward-state connectivity were associated with improvements reward-guided decision-making as well as with decreases in risk-taking. Finally, NAcc tissue-iron mediated age-related changes and was associated with variability in connectivity, and developmental increases in NAcc R2' corresponded with developmental decreases in connectivity. Our results provide evidence that dopamine-related striatal properties contribute to the specialization of frontostriatal circuitry, potentially underlying changes in risk-taking and reward sensitivity into adulthood.

Parkinson's disease: Alterations in iron and redox biology as a key to unlock therapeutic strategies

A plethora of studies indicate that iron metabolism is dysregulated in Parkinson's disease (PD). The literature reveals well-documented alterations consistent with established dogma, but also intriguing paradoxical observations requiring mechanistic dissection. An important fact is the iron loading in dopaminergic neurons of the substantia nigra pars compacta (SNpc), which are the cells primarily affected in PD. Assessment of these changes reveal increased expression of proteins critical for iron uptake, namely transferrin receptor 1 and the divalent metal transporter 1 (DMT1), and decreased expression of the iron exporter, ferroportin-1 (FPN1). Consistent with this is the activation of iron regulator protein (IRP) RNA-binding activity, which is an important regulator of iron homeostasis, with its activation indicating cytosolic iron deficiency. In fact, IRPs bind to iron-responsive elements (IREs) in the 3ꞌ untranslated region (UTR) of certain mRNAs to stabilize their half-life, while binding to the 5ꞌ UTR prevents translation. Iron loading of dopaminergic neurons in PD may occur through these mechanisms, leading to increased neuronal iron and iron-mediated reactive oxygen species (ROS) generation. The "gold standard" histological marker of PD, Lewy bodies, are mainly composed of α-synuclein, the expression of which is markedly increased in PD. Of note, an atypical IRE exists in the α-synuclein 5ꞌ UTR that may explain its up-regulation by increased iron. This dysregulation could be impacted by the unique autonomous pacemaking of dopaminergic neurons of the SNpc that engages L-type Ca+2 channels, which imparts a bioenergetic energy deficit and mitochondrial redox stress. This dysfunction could then drive alterations in iron trafficking that attempt to rescue energy deficits such as the increased iron uptake to provide iron for key electron transport proteins. Considering the increased iron-loading in PD brains, therapies utilizing limited iron chelation have shown success. Greater therapeutic advancements should be possible once the exact molecular pathways of iron processing are dissected.

Cannabis for Restless Legs Syndrome

Restless legs syndrome (RLS) is a chronic sensorimotor disorder characterized by an urge to move the legs. This urge is often accompanied by pain or other uncomfortable and unpleasant sensations, it either occurs or worsens during rest, particularly in the evening and/or at night, and temporarily improves with activity. Affecting nearly 3% of the North American and European populations in its moderate-to-severe form, RLS has a considerable negative impact on the quality of life, and sleep and is associated with significant morbidity. Although new developments have deepened our understanding of the disorder, yet, the corresponding pathophysiologic features that underlie the sensorimotor presentation are still not fully understood. Usually, symptoms respond well to dopamine agonists (DA), anticonvulsants, or opiates, used either alone or in any combination, but still, a subset of patients remains refractory to medical therapy and serious side effects such as augmentation and impulse control disorder may occur in patients with RLS under DA. Convincing treatment alternative are lacking but recently patients' spontaneous reports of a remarkable and total remission of RLS symptoms following cannabis use has been reported. The antinociceptive effect of marijuana has been documented in many painful neurological conditions and the potential benefit of cannabis use in patients with refractory RLS should, therefore, be questioned by robust clinical trials. Here, we review basic knowledge of RLS and the putative mechanisms by which cannabis may exert its analgesic effects.

Deficiency of Meis1, a transcriptional regulator, in mice and worms: Neurochemical and behavioral characterizations with implications in the restless legs syndrome

Restless legs syndrome is a sleep-related sensorimotor neurological disease affecting up to 10% of the population. Genetic analyses have identified Myeloid Ecotropic viral Integration Site 1 (MEIS1), a transcriptional regulator, to be associated with not only the restless legs syndrome but also self-reported symptoms of insomnia and sleep. This study is to determine if Meis1 deficiency in mice can lead to restless legs syndrome-like phenotypes, and if it is the case, what the underlying mechanisms are. We used two genetic model systems, Caenorhabditis elegans and mice. Egg retention assay and fluorescent reporters were used with C. elegans. For mice, we performed behavioral tests, serum and brain iron detection, qRT-PCR, western blot, immunohistochemistry, and in vitro brain-slice recording. Our results showed that with C. elegans, the function of dop-3, an orthologue of DRD2, was diminished after the knockdown of unc-62, an ortholog of MEIS1. Additionally, unc-62 knockdown led to enhanced transcription of the orthologue of tyrosine hydroxylase, cat-2. Meis1 knockout mice were hyperactive and had a rest-phase-specific increased probability of waking. Moreover, Meis1 knockout mice had increased serum ferritin and altered striatal dopaminergic and cholinergic systems. Specifically, Meis1 knockout mice showed an increased mRNA level but decreased protein level of tyrosine hydroxylase in the striatum. Furthermore, Meis1 knockout mice had increased striatal dopamine turnover and decreased spontaneous firing regularity of striatal cholinergic interneurons. Our data suggest that Meis1 knockout mice have restless legs syndrome-like motor restlessness and changes in serum ferritin levels. The symptoms may be related to dysfunctional dopaminergic and cholinergic systems.

The impact of brain iron accumulation on cognition: A systematic review

Iron is involved in many processes in the brain including, myelin generation, mitochondrial function, synthesis of ATP and DNA and the cycling of neurotransmitters. Disruption of normal iron homeostasis can result in iron accumulation in the brain, which in turn can partake in interactions which amplify oxidative damage. The development of MRI techniques for quantifying brain iron has allowed for the characterisation of the impact that brain iron has on cognition and neurodegeneration. This review uses a systematic approach to collate and evaluate the current literature which explores the relationship between brain iron and cognition. The following databases were searched in keeping with a predetermined inclusion criterion: Embase Ovid, PubMed and PsychInfo (from inception to 31st March 2020). The included studies were assessed for study characteristics and quality and their results were extracted and summarised. This review identified 41 human studies of varying design, which statistically assessed the relationship between brain iron and cognition. The most consistently reported interactions were in the Caudate nuclei, where increasing iron correlated poorer memory and general cognitive performance in adulthood. There were also consistent reports of a correlation between increased Hippocampal and Thalamic iron and poorer memory performance, as well as, between iron in the Putamen and Globus Pallidus and general cognition. We conclude that there is consistent evidence that brain iron is detrimental to cognitive health, however, more longitudinal studies will be required to fully understand this relationship and to determine whether iron occurs as a primary cause or secondary effect of cognitive decline.

Magnesium, Iron, Zinc, Copper and Selenium Status in Attention-Deficit/Hyperactivity Disorder (ADHD)

In this study, we critically review the literature concerning the relation of Mg, Fe, Zn, Cu and Se and attention-deficit/hyperactivity disorder (ADHD). Elemental status is estimated using peripheral blood parameters, hair, urine, daily intake and response to supplementation. The observed associations between concentration levels of the elements Mg, Fe, Zn, Cu and Se and ADHD symptoms are contradictory. This is partly due to the heterogeneity and complexity of the disorder. As a trend, lower ferritin and zinc levels can be observed. However, this correlation is not causative, as illustrated by placebo-controlled trials reporting conflicting evidence on the efficacy of supplementation. Well-defined studies on changes in concentration levels of the elements in relation to ADHD symptoms before and after treatment with therapeutics it will be possible to shed more light on the significance of these elements in this behavioral disorder. The discussion on whether a change in concentration of an element is cause or consequence of ADHD is not within the scope of this article.

Clinical Factors Affecting the Therapeutic Efficacy of Evening Primrose Oil on Mastalgia

BACKGROUND

Saturated fatty acid esters may cause mastalgia via hypersensitivity of breast epithelium to circulating hormones. Evening primrose oil (EPO) may restore the saturated/unsaturated fatty acid balance and decrease sensitivity to steroidal hormones or prolactin. Conflicting results exist regarding EPO treatment for mastalgia. The aim of this study was to determine the effectiveness of EPO and factors affecting its efficacy in treatment of mastalgia.

METHODS

The study included 1015 patients, ages 14-82 (mean age 42.21 ± 10.8), admitted to Acibadem Breast Clinic between January 2015 and March 2018. The patients were divided into group I (n = 581) treated with EPO (1300 mg, twice a day) and group II (n = 434) treated with paracetamol (500 mg, twice a day). The visual analog scale was used to assess EPO's therapeutic efficacy, compared with paracetamol, measured at admittance, 2 weeks, and 6 weeks. Clinical factors affecting the efficacy of EPO were analyzed.

RESULTS

The therapeutic efficacy of EPO on mastalgia was significantly higher than with paracetamol (p < 0.001). Factors significantly affecting the efficacy of EPO treatment were hormone replacement therapy (HRT), IUD-with-levonorgestrel, iron deficiency, overt hypothyroidism, and Hashimoto thyroiditis (p < 0.01). Replacement of iron or thyroid hormone efficiently treated mastalgia in patients that did not respond to EPO treatment. Side effects (allergy, anxiety, blurred vision, constipation, and nausea) were rare and not statistically significant (p = 0.88).

CONCLUSION

EPO can be used in the treatment of mastalgia without significant side effects. HRT, IUD-with-levonorgestrel, iron deficiency, overt hypothyroidism, and Hashimoto thyroiditis significantly affect the efficacy of EPO on mastalgia.

Irritability and Perceived Expressed Emotion in Adolescents With Iron Deficiency and Iron Deficiency Anemia: A Case-Control Study

The objective of this study was to assess the difference in irritability and perceived expressed emotion (EE) between adolescents with iron deficiency (ID) or iron deficiency anemia (IDA) and their healthy peers. In addition, we aimed to investigate the relationship between hemogram parameters, irritability, and perceived EE in adolescents with ID and IDA. The sample of this single-center cross-sectional case-control study consisted of 89 adolescents from 12 to 17 years of age. Of the participants, 19 had been diagnosed with ID, 31 had IDA, and 39 were healthy controls. Significant differences in the self-reported and parent-reported irritability scores were observed between the ID group and the control group and between the IDA group and the control group. There was also a significant difference in the subscale of irritability between the ID group and the control group. The difference between the IDA and control groups in the intrusiveness subscale was found to be significant as well. Adolescents with IDA and ID exhibited significantly perceived irritability compared with the control group. In terms of irritability, adolescents with IDA and ID revealed greater irritability than their healthy peers. The results of this study suggest that irritability and perceived EE should be investigated in cases of ID, whether with or without anemia. As chronic diseases may benefit substantially from psychiatric consultation, psychosocial evaluation and intervention should be considered a complementary treatment option in the management of ID and IDA.

BTBD9 and dopaminergic dysfunction in the pathogenesis of restless legs syndrome

Restless legs syndrome (RLS) is characterized by an urge to move legs, usually accompanied by uncomfortable sensations. RLS symptoms generally happen at night and can be relieved by movements. Genetic studies have linked polymorphisms in BTBD9 to a higher risk of RLS. Knockout of BTBD9 homolog in mice (Btbd9) and fly results in RLS-like phenotypes. A dysfunctional dopaminergic system is associated with RLS. However, the function of BTBD9 in the dopaminergic system and RLS is not clear. Here, we made use of the simple Caenorhabditis elegans nervous system. Loss of hpo-9, the worm homolog of BTBD9, resulted in hyperactive egg-laying behavior. Analysis of genetic interactions between hpo-9 and genes for dopamine receptors (dop-1, dop-3) indicated that hpo-9 and dop-1 worked similarly. Reporter assays of dop-1 and dop-3 revealed that hpo-9 knockout led to a significant increase of DOP-3 expression. This appears to be evolutionarily conserved in mice with an increased D₂ receptor (D₂R) mRNA in the striatum of the Btbd9 knockout mice. Furthermore, the striatal D₂R protein was significantly decreased and Dynamin I was increased. Overall, activities of DA neurons in the substantia nigra were not altered, but the peripheral D₁R pathway was potentiated in the Btbd9 knockout mice. Finally, we generated and characterized the dopamine neuron-specific Btbd9 knockout mice and detected an active-phase sleepiness, suggesting that dopamine neuron-specific loss of Btbd9 is sufficient to disturb the sleep. Our results suggest that increased activities in the D₁R pathway, decreased activities in the D₂R pathway, or both may contribute to RLS.

Association between anemia and maternal depression: A systematic review and meta-analysis

Previous observational epidemiological studies have reported inconsistent findings regarding the association between anemia and the risk of maternal depression. In the present study, we investigated the relationship between anemia and the risk of maternal depression using a meta-analysis. We searched PubMed, EMBASE, and the bibliographies of relevant articles in May 2019. Three evaluators independently reviewed and selected the eligible studies based on the predetermined selection criteria. A random-effects model was employed to calculate meta-estimates of the association between anemia and maternal depression. Of the 1305 articles, 15 observational epidemiological studies (five case-control studies and 10 cohort studies) were included in the final analysis. A total of 32,792,378 women were included. Anemia was significantly associated with an increased risk of maternal depression in the random-effects meta-analysis of 15 studies (OR/RR: 1.53, 95% CI: 1.32-1.78). The association was consistent in both antepartum (OR/RR: 1.36, 95% CI: 1.07-1.72) and postpartum depression (OR/RR: 1.53, 95% CI: 1.32-1.78). Subgroup meta-analyses based on definition of anemia, definition of depression, and methodological quality reported consistent findings. The current meta-analysis showed that anemia was associated with an increased risk of maternal depression.

Striatal histamine mechanism in the pathogenesis of restless legs syndrome

STUDY OBJECTIVES

Restless legs syndrome (RLS) has been hypothesized to be generated by abnormal striatal dopamine transmission. Dopaminergic drugs are effective for the treatment of RLS. However, long-term use of dopaminergic drugs causes adverse effects. We used iron-deficient (ID) and iron-replacement (IR) rats to address the neuropathology of RLS and to determine if a histamine H3 receptor (H3R) antagonist might be a useful treatment. Histamine H3R antagonists have been shown to decrease motor activity.

METHODS

Control and ID rats were surgically implanted with electrodes for polysomnographic recording. After 3 days of baseline polysomnographic recordings, rats were systemically injected with the H3R agonist, α-methylhistamine, and antagonist, thioperamide. Recordings were continued after drug injection. Striatal H3R levels from control, ID, and IR rats were determined by western blots. Blood from control, ID, and IR rats was collected for the measurement of hematocrit levels.

RESULTS

α-Methylhistamine and thioperamide increased and decreased motor activity, respectively, in control rats. In ID rats, α-methylhistamine had no effect on motor activity, whereas thioperamide decreased periodic leg movement (PLM) in sleep. Sleep-wake states were not significantly altered under any conditions. Striatal H3R levels were highest in ID rats, moderate to low in IR rats, and lowest in control rats. Striatal H3R levels were also found to positively and negatively correlate with PLM in sleep and hematocrit levels, respectively.

CONCLUSIONS

A striatal histamine mechanism may be involved in ID anemia-induced RLS. Histamine H3R antagonists may be useful for the treatment of RLS.

Neural circuitry and mechanisms of waiting impulsivity: relevance to addiction

Impatience-the failure to wait or tolerate delayed rewards (e.g. food, drug and monetary incentives)-is a common behavioural tendency in humans. However, when rigidly and rapidly expressed with limited regard for future, often negative consequences, impatient or impulsive actions underlie and confer susceptibility for such diverse brain disorders as drug addiction, attention-deficit hyperactivity disorder (ADHD) and major depressive disorder. Consequently, 'waiting' impulsivity has emerged as a candidate endophenotype to inform translational research on underlying neurobiological mechanisms and biomarker discovery for many of the so-called impulse-control disorders. Indeed, as reviewed in this article, this research enterprise has revealed a number of unexpected targets and mechanisms for intervention. However, in the context of drug addiction, impulsive decisions that maximize short-term gains (e.g. acute drug consumption) over longer-term punishment (e.g. unemployment, homelessness, personal harm) defines one aspect of impulsivity, which may or may not be related to rapid, unrestrained actions over shorter timescales. We discuss the relevance of this distinction in impulsivity subtypes for drug addiction with reference to translational research in humans and other animals. This article is part of the theme issue 'Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications'.

Longitudinal Development of Brain Iron Is Linked to Cognition in Youth

Brain iron is vital to multiple aspects of brain function, including oxidative metabolism, myelination, and neurotransmitter synthesis. Atypical iron concentration in the basal ganglia is associated with neurodegenerative disorders in aging and cognitive deficits. However, the normative development of brain iron concentration in adolescence and its relationship to cognition are less well understood. Here, we address this gap in a longitudinal sample of 922 humans aged 8-26 years at the first visit (M = 15.1, SD = 3.72; 336 males, 486 females) with up to four multiecho T2* scans each. Using this sample of 1236 imaging sessions, we assessed the longitudinal developmental trajectories of tissue iron in the basal ganglia. We quantified tissue iron concentration using R2* relaxometry within four basal ganglia regions, including the caudate, putamen, nucleus accumbens, and globus pallidus. The longitudinal development of R2* was modeled using generalized additive mixed models (GAMMs) with splines to capture linear and nonlinear developmental processes. We observed significant increases in R2* across all regions, with the greatest and most prolonged increases occurring in the globus pallidus and putamen. Further, we found that the developmental trajectory of R2* in the putamen is significantly related to individual differences in cognitive ability, such that greater cognitive ability is increasingly associated with greater iron concentration through late adolescence and young-adulthood. Together, our results suggest a prolonged period of basal ganglia iron enrichment that extends into the mid-twenties, with diminished iron concentration associated with poorer cognitive ability during late adolescence.SIGNIFICANCE STATEMENT Brain tissue iron is essential to healthy brain function. Atypical basal ganglia tissue iron levels have been linked to impaired cognition in iron deficient children and adults with neurodegenerative disorders. However, the normative developmental trajectory of basal ganglia iron concentration during adolescence and its association with cognition are less well understood. In the largest study of tissue iron development yet reported, we characterize the developmental trajectory of tissue iron concentration across the basal ganglia during adolescence and provide evidence that diminished iron content is associated with poorer cognitive performance even in healthy youth. These results highlight the transition from adolescence to adulthood as a period of dynamic maturation of tissue iron concentration in the basal ganglia.

The Prevalence of Insomnia and the Link between Iron Metabolism Genes Polymorphisms, TF rs1049296 C>T, TF rs3811647 G>A, TFR rs7385804 A>C, HAMP rs10421768 A>G and Sleep Disorders in Polish Individuals with ASD

Iron deficiency have been found to be linked to sleep disorders. Both genetic and environmental factors are risk factors for skewed iron metabolism, thus sleep disruptions in autism spectrum disorders (ASD). The aim of our study was to assess the prevalence of single nucleotide polymorphisms (SNPs) within transferrin gene (TF) rs1049296 C>T, rs3811647 G>A, transferrin receptor gene (TFR) rs7385804 A>C, and hepcidin antimicrobial peptide gene (HAMP) rs10421768 A>G in Polish individuals with ASD and their impact on sleep pattern. There were 61 Caucasian participants with ASD and 57 non-ASD controls enrolled. Genotypes were determined by real-time PCR using TaqMan SNP assays. The Athens Insomnia Scale (AIS) was used to identify sleep disruptions. There were 32 cases (57.14%) with insomnia identified. In the ASD group, the defined counts of genotypes were as follows: TF rs1049296, C/C n = 41 and C/T n = 20; TF rs3811647, G/G n = 22, G/A n = 34, and A/A n = 5; TFR rs7385804, A/A n = 22, A/C n = 29, and C/C n = 10; and HAMP rs10421768, A/A n = 34, A/G n = 23, and G/G n = 4. There were no homozygous carriers of the TF rs1049296 C>T minor allele in the ASD group. All analyzed SNPs were not found to be linked to insomnia. The investigated polymorphisms are not predictors of sleep disorders in the analyzed cohort of individuals with ASD.

The Role of BTBD9 in Striatum and Restless Legs Syndrome

Restless legs syndrome (RLS) is a sensory-motor neurological disorder characterized by uncomfortable sensations in the extremities, generally at night, which is often relieved by movements. Genome-wide association studies (GWAS) have identified mutations in BTBD9 conferring a higher risk of RLS. Knockout of the BTBD9 homolog in mice (Btbd9) and fly results in motor restlessness and sleep disruption. Clinical studies have found RLS patients have structural and functional abnormalities in the striatum; however, whether and how striatal pathology contributes to the pathogenesis of RLS is not known. Here, we used fMRI to map regions of altered synaptic activity in basal ganglia of systematic Btbd9 knock-out (KO) mice. We further dissected striatal circuits using patch-clamp electrophysiological recordings in brain slices. Two different mouse models were generated to test the effect of specific knockout of Btbd9 in either striatal medium spiny neurons (MSNs) or cholinergic interneurons (ChIs) using the electrophysiological recording, motor and sensory behavioral tests. We found that Btbd9 KO mice showed enhanced neural activity in the striatum, increased postsynaptic currents in the MSNs, and decreased excitability of the striatal ChIs. Knocking out Btbd9 specifically in the striatal MSNs, but not the ChIs, led to rest-phase specific motor restlessness, sleep disturbance, and increased thermal sensation in mice, which are consistent with results obtained from the Btbd9 KO mice. Our data establish the role of Btbd9 in regulating the activity of striatal neurons. Increased activity of the striatal MSNs, possibly through modulation by the striatal ChIs, contributes to the pathogenesis of RLS.

Comparing the effectiveness of vitamin D plus iron vs vitamin D on depression scores in anemic females: Randomized triple-masked trial

Background: Low levels of 25-hydroxyvitamin D (25(OH)D) have been related to depression and anxiety. It seems that anemia is associated with vitamin D deficiency. We aimed to evaluate the effects of iron-vitamin D co-supplementation versus vitamin D alone on depression scores in anemic females with low levels of serum 25-hydroxyvitamin D. Methods: This randomized controlled trial was conducted on eighty premenopausal females who were recruited between May 2015 and October 2015 from primary health care centers. Women with anemia and low concentrations of 25(OH)D were randomized to either 1000 IU/d vitamin D plus 27 mg/d iron (D-Fe) or vitamin D plus placebo supplements (D-P) for 12 weeks. Depressive and anxious symptoms were evaluated with the Beck Depression Inventory (BDI) with subscales 1-13 and 14-21 and Beck Anxiety Inventory (BAI). To compare the groups, Mann-Whitney or chi-squared tests were used and within groups comparison was performed using Wilcoxon signed ranks test. The study was registered on www.clinicaltrial.org as NC 01876563. Results: The serum concentrations of 25(OH)D were increased significantly in both groups at the end of the study. In both groups, there was a significant improvement in total BDI, the BDI subscale, and the BAI scores (p<0.001). No differences were found between groups (p>0.05). Conclusion: Although the potential positive effect of vitamin D on mental health was evident, iron plus vitamin D co-supplementation did not demonstrate any significant benefits over vitamin D alone, neither in depression score reduction nor anxiety symptoms.

D3 and D1 receptors: The Yin and Yang in the treatment of restless legs syndrome with dopaminergics

Dopaminergic treatments targeting the D3 receptor subtype to reduce the symptoms of RLS show substantial initial clinical benefits but fail to maintain their efficacy over time. Sensorimotor circuits in the spinal cord are the gateway for the sensory processing of the symptoms and critical for the associated leg movements that relieve the symptoms and the periodic limb movements that often develop during sleep. There is a high preponderance of the inhibitory D3 receptor in the sensory-processing areas of the spinal cord (dorsal horn), whereas the motor areas in the ventral horn more strongly express the excitatory D1 receptor subtype. D3 and D1 receptors can form functional heteromeric ensembles that influence each other. In the spinal cord, long-term treatment with D3 receptor agonists is associated with the upregulation of the D1 receptor subtype and block of D1 receptor function at this stage can restore the D3 receptor effect. Alternate scenarios for a role of dopamine involve a role for the D5 receptor in regulating motor excitability and for the D4 receptor subtype in controlling D3-like effects. A model emerges that proposes that the behavioral changes in RLS, while responsive to D3 receptor agonists, may be ultimately be the result of unmasked increased D1-like receptor activities.