Cognitive function and neurophysiological evaluation in early-treated hypothyroid children

Neuropsychological Alterations in Patients with Congenital Hypothyroidism Treated with Levothyroxine: Linked Factors and Thyroid Hormone Hyposensitivity

Eighty-five percent of the studies of patients with congenital hypothyroidism (CH) treated with Levothyroxine (L-T₄) report neuropsychological sequelae throughout life. In neonates and infants, there is a deficit in sensorimotor skills (impaired balance). In preschool and elementary school children and adolescents, there are alterations in intellectual quotient (low scores), language (delayed phonological acquisition), memory (visual, verbal, visuospatial, visuoconstructive, autobiographical, and semantic), sensorimotor skills (impaired fine and gross motor control), and visuoconstructive–visuospatial domain (low scores in spatial location, block design, and object assembly). These neuropsychological domains are also affected in young adults, except for language (adequate verbal fluency) and visuoconstructive–visuospatial domain (no data). The onset and severity of neuropsychological sequelae in patients with treated CH depend on several factors: extrinsic, related to L-T₄ treatment and social aspects, and intrinsic, such as severity and etiology of CH, as well as structural and physiological changes in the brain. In this review, we hypothesized that thyroid hormone hyposensitivity (THH) could also contribute to neuropsychological alterations by reducing the effectiveness of L-T₄ treatment in the brain. Thus, further research could approach the THH hypothesis at basic and clinical levels to implement new endocrinological and neuropsychological therapies for CH patients.

The Effects of Six-Month L-Thyroxine Treatment on Cognitive Functions and Event-Related Brain Potentials in Children with Subclinical Hypothyroidism

OBJECTIVE

The aim of this study was to investigate the cognitive status of children with subclinical hypothyroidism (SH) before and after L-thyroxine (L-T4) treatment using event-related potentials (ERPs) and neuropsychological tests.

METHODS

This prospective study was conducted on a series of 20 children with mild SH (free T4 normal and thyroid-stimulating hormone level within 5-10 µIU/L) who underwent clinical and cognitive assessment before L-T4 treatment and 6 months afterwards. The recordings of ERPs were done at the time of diagnosis and after 6 months of euthyroid state. Neuropsychiatric tests for attention, perception, close and remote memory were performed on all patients and on the control group which consisted of 20 healthy children of normal intelligence.

RESULTS

While pretreatment verbal memory (VM) and verbal recall (VR) scores of the SH group were significantly lower than those of the control group (p=0.004 and 0.012, respectively), no significant differences between the post-treatment and control groups were found in these scores after 6 months of L-T4 treatment. Post-treatment VM and VR scores were significantly higher than the pretreatment scores in the SH group (p=0.008 and p=0.0001). There were no significant differences between the pre-and post-treatment values of electrophysiological evaluation in N1, P2, P3 latencies or P3 amplitude (p>0.05), although there was a significant decrease in N2 latency in the post-treatment group (p=0.03).

CONCLUSION

SH affects cognition in children and L-T4 replacement therapy leads to normalization of cognitive functions. Neuropsychological tests can be used as complementary measures in the evaluation of children with SH. Determining the association between ERPs and SH would contribute to the comprehensive evaluation of these children.

Factors associated with hearing impairment in patients with congenital hypothyroidism treated since the neonatal period: a national population-based study

CONTEXT

Untreated hypothyroidism is known to impair hearing, but little is known about the long-term hearing of patients treated for congenital hypothyroidism (CH) since the neonatal period.

OBJECTIVE

The purpose of this study was to assess hearing and its determinants in a population-based registry of young adult patients with CH.

DESIGN, SETTING, AND PARTICIPANTS

Self-declared hearing loss was evaluated in 1202 of the 1748 eligible patients with CH who completed a questionnaire on health status at a median age of 23.4 years. Audiograms were obtained for one third of the patients declaring hearing loss (37 of 107).

MAIN OUTCOME MEASURES

Self-declared hearing loss and audiogram characteristics for patients reporting hearing impairment were measured.

RESULTS

These patients had a risk of self-declared hearing loss more than 3 times higher than that for the reference population (relative risk [RR] = 3.7; 95% confidence interval [CI], 2.9-4.7). Hearing impairment was diagnosed at a median age of 7.0 (25th-75th percentiles, 3.4-19.0) years, and 17% of affected patients required hearing support in early adulthood. Hearing loss was associated with the type of CH (patients with athyreosis and gland in situ were more frequently affected than those with an ectopic gland [RR = 2.61; 95% CI, 1.77-3.88]), with disease severity, as assessed by bone maturation delay at the time of diagnosis, with at least one knee epiphyseal ossification center absent in the most severe form (RR = 2.29; 95% CI, 1.39-3.79), and with other associated chronic diseases (RR = 3.64; 95% CI, 2.35-5.62). A trend for association with serum free T4 concentration at diagnosis was also observed (RR = 1.47; 95% CI, 0.96-2.23). Hearing loss was mostly bilateral (90%), mild to moderate (96%), of the sensorineural type (76%), and concerned high or very high frequencies.

CONCLUSION

Despite major improvements in prognosis, hearing loss remains a significant problem, particularly in patients with severe CH. Parents and primary care providers should be aware of this risk, because early diagnosis and intervention could improve the long-term prognosis in these patients.

Prenatal exposure to organochlorine compounds and neonatal thyroid stimulating hormone levels

It has been suggested that prenatal exposure to some organochlorine compounds (OCs) may adversely affect thyroid function and may, therefore, impair neurodevelopment. The main aim of this study was to examine the relationship of cord serum levels of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (4,4'-DDT), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (4,4'-DDE), β-hexachlorocyclohexane (β-HCH), hexachlorobenzene (HCB), four individual polychlorobiphenyl (PCB) congeners (118, 138, 153, and 180), and their sum, with neonatal thyroid stimulating hormone (TSH) levels in blood samples in a mother-infant cohort in Valencia, Spain. This study included 453 infants born between 2004 and 2006. We measured OC concentrations in umbilical cord serum and TSH in blood of newborns shortly after birth. Associations between neonatal TSH levels and prenatal OC exposure adjusted for covariates were assessed using multivariate linear regression analyses. Neonatal TSH levels tended to be higher in newborns with β-HCH levels in umbilical cord above 90th percentile (104 ng/g lipid) than in those with levels below the median (34 ng/g lipid), with an adjusted increment in neonatal TSH levels of 21% (95% confidence interval=-3, 51; P=0.09). No statistically significant association was found between the remaining OCs and TSH at birth. Prenatal exposure to β-HCH may affect neonatal thyroid hormone status and its function in neurological development.

Headache and cognitive profile in children: a cross-sectional controlled study

We investigated whether children affected by tension-type headache and migraine without aura, compared with a healthy control group that was matched by age, culturally and socioeconomically display a diverse intellectual functioning and have a separate “cognitive profile”. A cross-sectional study was conducted from January 2006 to November 2008 at “Sapienza University” in Rome. A total of 134 children were diagnosed as being affected by either migraine without aura (93) or tension-type headache (41). On the basis of our exclusion/inclusion criteria, we enrolled 82 of these 134 children, 63 of whom were affected by migraine without aura and 19 by tension-type headache. On entry, cognitive functions were assessed in both the affected subjects and the control group by the Wechsler Intelligence Scale for Children-revised. Significant differences were found between the headache and control groups in the mean total intelligence quotient and verbal intelligence quotient scores (p < 0.001). Significant negative correlations were found between the total intelligence quotient, verbal intelligence quotient, performance intelligence quotient and the frequency of attacks (r = −0.55 and p < 0.001, r = −0.61 and p < 0.001, r = −0.29 and p < 0.01, respectively), as well as between the total intelligence quotient score and the age at headache onset (r = 0.234, p < 0.05). Our results suggest that the cognitive profile of children affected by headache should be assessed at the first child neurology outpatient observation. From a therapeutic point of view, although within a normal range, the abilities most likely to be less brilliant in such children are verbal skills.

Importância do fonoaudiólogo no acompanhamento de indivíduos com hipotireoidismo congênito

TEMA: o hipotireoidismo congênito é uma alteração metabólica que traz conseqüência graves para indivíduos não tratados e mesmo as crianças que realizam o tratamento podem apresentar distúrbios do desenvolvimento. O Programa Nacional de Triagem Neonatal, instituído pelo Ministério da Saúde, prevê o acompanhamento longitudinal de indivíduos com equipe multidisciplinar. Entretanto, a Fonoaudiologia não é incluída nesta equipe. Deste modo, considerando a ocorrência de distúrbios da comunicação nestes indivíduos, realizou-se levantamento bibliográfico nas bases de dados Lilacs, MedLine e PubMed, no período de 1987 a 2007, referente às alterações em habilidades do desenvolvimento decorrentes do hipotireoidismo congênito. OBJETIVO: verificar, na literatura científica, presença de alterações do desenvolvimento em indivíduos com hipotireoidismo congênito e refletir sobre a importância da atuação fonoaudiológica, em conjunto com equipe multidisciplinar especializada, no acompanhamento dos mesmos. CONCLUSÃO: a literatura relata alterações nas habilidades do desenvolvimento (motoras, cognitivas, lingüísticas e de autocuidados) e destaca que crianças com hipotireoidismo congênito são de risco para alterações no desenvolvimento lingüístico e, portanto, necessitam do acompanhamento longitudinal do desenvolvimento comunicativo. Torna-se evidente a importância da atuação do fonoaudiólogo nos Programas de Triagem Neonatal credenciados pelo Ministério da Saúde. Ressalta-se ainda a necessidade de investigações referentes às outras alterações metabólicas contempladas nestes programas, nas quais o fonoaudiólogo pode atuar de modo a prevenir, habilitar e reabilitar os distúrbios da comunicação, contribuindo para o trabalho em equipe, promovendo saúde nesta população.

TSH concentration within the normal range is associated with cognitive function and ADHD symptoms in healthy preschoolers

OBJECTIVE

Thyroid hormone concentrations outside the normal range affect brain development, but their specific influence on behaviour and mental abilities within normal values is unknown. The objective of this study was to investigate whether thyroid hormone concentrations are related to neurodevelopment and ADHD (attention deficit and hyperactivity disorder) symptoms in healthy preschoolers. DESIGN SUBJECTS AND MEASUREMENTS: Children from two general population birth cohorts in Menorca (n = 289) and Ribera d'Ebre (n = 53), Spain, were assessed in a cross-sectional study at the age of 4. Thyroid hormones (free T4 and T3) and TSH concentrations were measured and mental and motor development was assessed using McCarthy's scales for neuropsychological outcomes and ADHD-DSM-IV for attention deficit and hyperactivity/impulsivity symptoms.

RESULTS

Children with TSH concentrations in the upper quartile of the normal range performed lower on McCarthy's scales and were at higher risk for attention deficit and hyperactivity/impulsivity symptoms. In the Menorca cohort, a decrease of 5.8 (P < 0.05) and 6.9 (P < 0.01) points was observed in memory and quantitative skills, respectively. In contrast, high T4 concentrations were associated with decreased risk of having 1-5 attention deficit symptoms (odds ratio: 0.25; P < 0.01); these findings were observed in both cohorts despite differences in mean TSH concentrations. No associations were observed with T3.

CONCLUSIONS

Despite being within the normal range, high TSH concentrations are associated with a lower cognitive function and high TSH and low free T4 with ADHD symptoms in healthy preschoolers. Statistically significant differences were observed in the highest quartiles of TSH, suggesting a need for re-evaluation of the upper limit of the normal TSH range.

Young adults with severe congenital hypothyroidism: Cognitive event related potentials (ERPs) and the significance of an early start of thyroxine treatment

Congenital hypothyroidism (CH) has devastating effects upon brain development if left untreated. Despite early start of thyroxine treatment, patients still show subtle cognitive deficits compared to controls. We aimed to study auditory event related potentials (ERPs) in young CH adults (N = 12) to verify previous reports of normal attention functions measured by P3 in CH children. We also include ERP components (P1, N1, P2) allowing assessment of a wider range of auditory processing functions. No significant change in P3 latency or amplitude was found in the CH group, but a more subtle change in amplitude topography. A later start of thyroxine treatment was related to increased P3 latency and reduced amplitude. Group differences were found in early ERP components tapping sensory processing, sensory gating and selective attention. The results suggest persisting abnormalities in auditory processing and selective attention that may have influenced cognitive development.

Some neurological and psychiatric complications in the disorders of the thyroid gland

A pajzsmirigyhormonok alapvető fontosságúak a központi idegrendszer perinatális fejlődéséhez és a felnőtt agy működéséhez, elsősorban a specifikus célgének transzkripciójának szabályozásával. Fokozzák a kortikális szerotoninerg transzmissziót, szerepet játszanak a noradrenerg funkciók szabályozásában, és érintik a GABA-funkciót. A csecsemő- és kisgyermekkori hypothyreosis mentális retardációhoz vezet, felnőttkorban a demencia és a depresszió a leggyakoribb, de előfordulhat myxoedemás kóma, cerebellaris és agyidegtünetek, megnő a hajlam a cerebrovascularis kórképekre. A periféria részéről polyneuropathia, carpalis alagút syndroma, myalgia gyakori; ritka szövődmény a myokymia. Csaknem minden hyperthyreotikus betegnél előfordulnak minor pszichiátriai tünetek, ritkábban alakul ki pszichózis, demencia, konfúziós állapot, depresszió, apátiás thyreotoxicosis, thyreotoxikus krízis, epilepszia, pyramistünetek vagy chorea. A periféria részvételét krónikus thyreotoxikus myopathia, infiltratív ophthalmomyopathia, myasthenia gravis, thyreotoxikus periódikus hypokalaemiás bénulás és polyneuropathia jelezheti. A figyelemhiányos hiperaktivitásban szenvedők jelentős részénél generalizált pajzsmirigyhormon-rezisztenciát igazoltak. Magas antithyroid antitest titer jellemzi az akut-szubakut indulású, remissziókkal és relapszusokkal jellemezhető, súlyos, életveszélyes, de szteroidra jól reagáló, autoimmun, ritkán előforduló Hashimoto-encephalopathiát.

Median nerve conduction velocity and central conduction time measured with somatosensory evoked potentials in thyroxine-treated infants with Down syndrome

OBJECTIVE

The aim of this study was to determine whether thyroxine treatment would improve nerve conduction in infants with Down syndrome.

METHODS

A single-center, nationwide, randomized, double-blind, clinical trial was performed. Neonates with Down syndrome were assigned randomly to thyroxine (N = 99) or placebo (N = 97) treatment for 2 years. Daily thyroxine doses were adjusted regularly to maintain plasma thyrotropin levels in the normal range and free thyroxine concentrations in the high-normal range. The outcome measures were nerve conduction velocity and central conduction time, determined through median nerve somatosensory evoked potential recording, at the age of 24 months.

RESULTS

At the age of 24 months, somatosensory evoked potential recordings for 81 thyroxine-treated and 84 placebo-treated infants were available for analysis. Nerve conduction velocity and central conduction time did not differ significantly between the 2 treatment groups (nerve conduction velocity: thyroxine: 51.0 m/second; placebo: 50.1 m/second; difference: 0.9 m/second; central conduction time: thyroxine: 8.83 milliseconds; placebo: 8.73 milliseconds; difference: 0.1 milliseconds).

CONCLUSIONS

Postnatal thyroxine treatment of infants with Down syndrome did not alter somatosensory evoked potential-measured peripheral or central nerve conduction significantly. The absence of favorable effects suggests that pathologic mechanisms other than mild postnatal hypothyroidism underlie the impaired nerve conduction. The absence of adverse effects suggests that longstanding plasma free thyroxine concentrations in the high-normal range are not harmful to nerve maturation.

Effects of early high-dose levothyroxine treatment on auditory brain event-related potentials at school entry in children with congenital hypothyroidism

AIMS

We tested whether brain event-related potentials (ERPs) are normal in children with congenital hypothyroidism (CH) after early high-dose levothyroxine treatment.

METHODS

Auditory ERPs were recorded in 33 normal controls and in 15 children with CH at 5 years 9/12. Based on bone maturation at diagnosis, the CH group was divided into severe (n = 8) and moderate (n = 7) subgroups. CH patients were treated at a median age of 14 days with a mean initial dose of levothyroxine of 11.6 microg/kgxday. Two ERP components (N100 and N200) were measured and clinical follow-up variables collected.

RESULTS

The functional anatomical and cognitive organisation of the auditory system, as revealed by the analyses of ERP measures, did not differ between CH and controls, or between severe and moderate CH subjects. However, N200 latency was globally longer in the CH than in the control group (p = 0.01) and was positively correlated with the over-treatment index (r = 0.61; p < 0.05) and verbal IQ. N200 amplitude was negatively correlated with initial dose (r = -0.74; p < 0.005).

CONCLUSION

These data suggest that sensitive tools such as ERPs can reveal differences between CH and controls and relate these differences to the adequacy of treatment of CH.

Congenital hypothyroidism: influence of disease severity and L-thyroxine treatment on intellectual, motor, and school-associated outcomes in young adults

OBJECTIVE

To describe intellectual, motor, and school-associated outcome in young adults with early treated congenital hypothyroidism (CH) and to study the association between long-term outcome and CH variables acting at different points in time during early development (CH severity and early L-thyroxine treatment levels [0-6 years]).

METHODS

Neuropsychological tests were administered to all 49 subjects with CH identified during the first 3 years of the Norwegian neonatal screening program (1979-1981) at a mean age of 20 years and to 41 sibling control subjects (mean age: 21 years).

RESULTS

The CH group attained significantly lower scores than control subjects on intellectual, motor, and school-associated tests (total IQ: 102.4 [standard deviation: 13] vs 111.4 [standard deviation: 13]). Twelve (24%) of the 49 CH subjects had not completed senior high school, in contrast to 6% of the control subjects. CH severity (pretreatment serum thyroxine [T4]) correlated primarily with motor tests, whereas early L-thyroxine treatment levels were related to verbal IQ and school-associated tests. In multiple regression analysis, initial L-thyroxine dose (beta = 0.32) and mean serum T4 level during the second year (beta = 0.48) predicted Verbal IQ, whereas mean serum T4 level during the second year (beta = 0.44) predicted Arithmetic.

CONCLUSIONS

Long-term outcome revealed enduring cognitive and motor deficits in young adults with CH relative to control subjects. Verbal functions and Arithmetic were associated with L-thyroxine treatment variables, suggesting that more optimal treatment might be possible. Motor outcome was associated with CH severity, indicating a prenatal effect.

Acute effects of irradiation on cognition: changes in attention on a computerized continuous performance test during radiotherapy in pediatric patients with localized primary brain tumors

PURPOSE

To assess sustained attention, impulsivity, and reaction time during radiotherapy (RT) for pediatric patients with localized primary brain tumors.

METHODS AND MATERIALS

Thirty-nine patients (median age 12.3 years, range 5.9-22.9) with primary brain tumors were evaluated prospectively using the computerized Conners' continuous performance test (CPT) before and during conformal RT (CRT). The data were modeled to assess the longitudinal changes in the CPT scores and the effects of clinical variables on these changes during the first 50 days after the initiation of CRT.

RESULTS

The CPT scores exhibited an increasing trend for errors of omission (inattentiveness), decreasing trend for errors of commission (impulsivity), and slower reaction times. However, none of the changes were statistically significant. The overall index, which is an algorithm-based weighted sum of the CPT scores, remained within the range of normal throughout treatment. Older patients (age >12 years) were more attentive (p < 0.0005), less impulsive (p < 0.07), and had faster reaction times (p < 0.001) at baseline than the younger patients. The reaction time was significantly reduced during treatment for the older patients and lengthened significantly for the younger patients (p < 0.04). Patients with a shunted hydrocephalus (p < 0.02), seizure history (p < 0.0006), and residual tumor (p < 0.02) were significantly more impulsive. Nonshunted patients (p < 0.0001), those with more extensive resection (p < 0.0001), and patients with ependymoma (p < 0.006) had slower initial reaction times.

CONCLUSION

Children with brain tumors have problems with sustained attention and reaction time resulting from the tumor and therapeutic interventions before RT. The reaction time slowed during treatment for patients <12 years old. RT, as administered in the trial from which these data were derived, has limited acute effects on changes in the CPT scores measuring attention, impulsiveness, and reaction time.