Thyroid hormone and attention in school-age children with congenital hypothyroidism

The relationship between attention and thyroid hormone was examined using a retrospective database of 85 7-year-old children with congenital hypothyroidism who received psychological evaluations and thyroid function tests on the same day. Four unique subgroups with different levels of thyroxine and thyrotropin were compared on psychological tasks and measures of attention. Children with high levels of both hormones were found to be significantly more distractable on an index of cognitive attention but were reportedly less hyperactive. Level of thyroxine accounted for over 10% of the variance in attention.

Mild impairment of neuro-otological function in early treated congenital hypothyroidism

Pure tone audiometry, tympanometry, acoustic stapedial reflex thresholds (ASRTs), and auditory evoked brain stem responses (AEBRs) were carried out in 38 children with early treated congenital hypothyroidism aged 10-12 years, together with tests of vestibular function (electronystagraphy, rotational, and caloric tests). Sensorineural hearing loss with thresholds of greater than 15 dB was detected in 18 children (10 at 8 kHz only); only two children had more than 40 dB hearing loss, each in one ear. Raised ASRTs were found in eight children and two children had abnormal AEBRs. Of the 29 children tested, 12 had an abnormality of vestibular function. Although not significant at the 5% level, there was a tendency for the abnormalities to be more prevalent and severe in the children with more severe hypothyroidism, as judged by pretreatment plasma thyroxine. It is concluded that (i) mild abnormality of hearing is still common in children with congenital hypothyroidism despite early treatment but this is much less severe than that found before neonatal screening and (ii) mild abnormalities of vestibular function may be common in early treated congenital hypothyroidism.

Neuropsychologic development in early treated congenital hypothyroidism: analysis of literature data

The aim of this study was to determine the neuropsychologic development in patients with congenital (primary) hypothyroidism (CH) detected by screening and treated from early age. Seven studies were evaluated, including 675 CH patients and 570 controls. Criteria for inclusion of the studies were: 1) age of patients and controls > or = 5 y; 2) control group well defined in the original article. A meta-analysis of the data on the intellectual development was performed. All analyzed studies show a trend toward lower intelligence quotient (IQ) and--as far as investigated--poorer motor skills in CH patients compared with controls. Pooling of data showed a significant deficit of the mean IQ of 6.3 (95% confidence interval: 4.7-7.8). The most important independent risk factor for the eventual outcome appears to be the severity of CH (defined by initial thyroxine at the moment of diagnosis and by skeletal maturation); treatment variables do not seem to have an important effect the cognitive development. We conclude that CH, despite early detection and treatment, results in an IQ deficit; the severity of CH seems to be the most important individual risk factor. Our second conclusion is that, although biomedical risk factors are well investigated, the individual weight of these factors is yet largely unknown. This may be due to the variability of definitions and test tools, especially for the investigation of motor skills, that have been used.

Odor detection performance in hypothyroid and euthyroid rats

The influence of hypothyroidism on the odor detection ability of male Long-Evans rats was determined using high-precision olfactometry and a go/no-go operant task. Nonparametric signal detection measures of sensitivity and responsitivity, as well as measures of S+ response latency, the number of aborted trials, and session time were obtained in daily 200-trial test sessions prior to, during, and after 50 days of maintenance on 0.1% propylthiouracil (PTU). Similar determinations were made in control animals. Neither odor detection nor associated nonsensory performance measures were influenced by hypothyroidism. These results suggest that PTU-induced hypothyroidism does not affect the odor detection performance of rats.

Thyroid hormone and attention in congenital hypothyroidism

OBJECTIVES

To determine in school-age children with congenital hypothyroidism: (i) frequency of a high thyroxine/high thyrotropin profile; (ii) relations between different levels of thyroxine and thyrotropin and attentional function, and (iii) persistence of effects.

DESIGN

Retrospective analysis of an inception cohort.

SETTING

Clinical psychology laboratory in tertiary pediatric hospital.

SUBJECTS

Eighty-six 7 year olds identified with congenital hypothyroidism by newborn screening, who were participating in a long-term prospective study.

MAIN OUTCOME MEASURES

Wechsler Intelligence Scale for Children-Revised (WISC-R) and Wide Range Achievement Test-Revised (WRAT-R) were administered. WISC-R Full Scale, Verbal and Performance IQs were obtained as well as scores on individual subtests, and three ability composites. Freedom from Distractibility (FFD) served as the indicator of attention.

RESULTS

9.3% of 7 year olds had elevations of both T4 and TSH. These children scored significantly higher on word knowledge and spelling but had significantly lower Digit Span and FFD scores than those in groups with other hormone combinations. Level of thyroxine was the primary predictor of attention, accounting for 10.5% of the variance. Among 9 year olds, 6.1% had T4 and TSH elevations, and although they also scored lowest on FFD, these were not the same children with T4 and TSH elevations at age 7.

CONCLUSIONS

These results signify that a high T4/high TSH profile contributes to poorer attention. Because the individual children who showed the effect were not the same at the two ages, this suggests that thyroid hormone appears to play a role in regulating attention but does not indicate resistance.

Neuroendocrine evidence for an association between hypothyroidism, reduced central 5-HT activity and depression

OBJECTIVE

The incidence of depression in those with hypothyroidism is increased compared to healthy populations, though the mechanism for this is unclear. We tested the hypothesis that central 5-HT activity is reduced in hypothyroidism, and that this subsequently lowers the threshold for developing depression.

PATIENTS

Twenty subjects entered the study: 10 drug free hypothyroid patients and 10 age, sex, weight and menstrual cycle matched controls.

MEASUREMENTS

Patients were diagnosed as being depressed using DSM-IIIR criteria and rated using the Hamilton Rating Scale for Depression (HAM-D) and Beck Depression Inventory (BDI). Cortisol and prolactin responses to dexfenfluramine, a centrally acting 5-HT releasing agent, were used as an index of central 5-HT responsivity.

RESULTS

Both cortisol and PRL responses were reduced in the hypothyroid group relative to the controls. Peak cortisol responses were inversely correlated to TSH levels. Four of the 10 patients were clinically depressed. Depressed patients had higher TSH levels than their non-depressed counterparts, and TSH levels were positively correlated with HAM-D and BDI scores.

CONCLUSIONS

These findings support animal work suggesting that hypothyroidism reduces central 5-HT activity. They also suggest a threshold effect in that higher TSH levels predicted both lower 5-HT mediated endocrine responses and the presence of clinical depression.

Childhood IQ measurements in infants with transient congenital hypothyroidism

OBJECTIVE

In view of the fact that, during the first period of life, thyroid hormones are critical for brain development, we investigated whether even transient congenital hypothyroidism could affect the long-term intellectual development of affected infants.

DESIGN

A case-control study of intellectual development, auxometric parameters and thyroid function performed in late infancy in children with documented transient congenital hypothyroidism or hyperthyrotrophinaemia at birth.

PATIENTS

Nine children born in an endemic goitre area who had short-term transient congenital hypothyroidism or hyperthyrotrophinaemia after birth (TCH) were studied and compared to nine matched children born in the same area at the same time but having normal thyroid function at birth (N).

MEASUREMENTS

Global, verbal and performance IQs were evaluated on the Wechsler scale. Height, bone age, total and free thyroid hormones, thyroid volume, thyroglobulin, basal and TRH stimulated TSH were also measured.

RESULTS

Height and bone age were similar in the two groups. Thyroid function tests were also similar in the two groups except for basal and TRH stimulated serum TSH and serum Tg which were higher in the TCH than in the control group. Global, verbal and performance IQs were systematically lower in the TCH than in the N group. (78.3 +/- 11.1 vs 90.9 +/- 14.2, P < 0.05; 84.4 +/- 15.4 vs 96.2 +/- 14.8, P NS; 75.0 +/- 8.5 vs 89.2 +/- 12.5, P < 0.01 respectively).

CONCLUSION

Infants born and living in an academic goitre area, who had biochemical signs of thyroid hypo-function at birth, had a lower intelligence quotient at the age of 7-8 years than matched controls living in the same environmental conditions but with normal thyroid function at birth. The present findings strongly suggest that abnormalities in thyroid function at birth, even when transient, can adversely affect long-term intellectual development.

Delusional depression, hyperparathyroidism, and ECT

A woman with delusional depression and unsuspected primary hyperparathyroid disorders responded completely to electroconvulsive therapy (ECT). Hypercalcemia is a complicating factor in the treatment of delusional depression, but there is little evidence that it is causative and the use of ECT should not be delayed. The case adds to the literature confirming the efficacy and safety of ECT with physically ill patients when it may be a life-saving procedure.

Neurophysiologic studies and cognitive function in congenital hypothyroid children

Minor neurologic and intellectual impairments have been described in some congenital hypothyroid (CH) children in spite of early detection by neonatal screening. The aim of our study was to assess cognitive functions as well as neurophysiologic parameters in hypothyroid children and to compare children detected by neonatal screening (group A) versus hypothyroid patients clinically diagnosed before the beginning of the screening program (group B). Group A consisted of 15 children (13 girls, mean age at the beginning of treatment 33 d). Group B consisted of 11 patients (7 girls, mean age at the start of treatment 10.1 mo). Twenty age-matched healthy children were studied as a control group for neurophysiologic tests. Neurophysiologic tests (Auditory P 300, long latency somatosensory evoked potentials (LL-SEP) were performed along with IQ evaluation. Abnormalities of neurophysiologic tests were detected in 82% of clinically diagnosed hypothyroid children. Surprisingly, 47% of the children detected by neonatal screening, having normal mental development index, showed at least one abnormal neurophysiologic test. LL-SEP latencies were found significantly increased in both groups of CH patients compared with controls. Our data are suggestive for a prenatal or perinatal CNS damage in some children with congenital hypothyroidism, despite early treatment.

[Psychopathological risk in children with early onset of partial epilepsy]

In this study we compare the peculiarities of psychopathological risk in children with partial epilepsy versus children with chronic illness. Sixteen children affected by epilepsy with partial seizures, symptomatic or cryptogenetic (group A), are compared with 16 children affected by diabetes mellitus type 1 (group B) and with 16 early treated congenital hypothyroid children (group C). For the valuation we have used: 1) Rutter scales for parents; 2) questionnaire on maternal attitude towards epilepsy, modified for diabetes and hypothyroid children; 3) anamnestic interviews for epileptic patients; 4) individual observations. We have emphasized that: 1) the quality of life in children with epilepsy and their families is poorer compared to the ones of the other chronically ill children; 2) the attack is the most characterising factor of life quality of both group A and group B; 3) both group A and group B show an important anxiety for cognitive and behavioural disturbances; 4) in epilepsy families several factors contribute to the increased anxiety towards social life: occurrence of seizures, side effects of drugs, real or supposed underlying encephalopathy.

[Biological factors and resistance to antidepressive agents]

Concerning depressive disorders, biological factors remain relatively unknown. However, they might first be risk factors for depressive disorders and secondly could decrease the response to antidepressants. We studied hypothyroidism, diabetes and hypothalamic-pituitary-adrenal axis disorders. In terms of neurotransmitters, beta-adrenergic dysfunction may be involved in hypothyroidism and diabetes whereas a serotonergic dysfunction may be involved in hypothalamic-pituitary-adrenal axis disorders.

Long-term effects of L-thyroxine therapy for congenital hypothyroidism

OBJECTIVE

To study the effects of initial and concurrent dose levels of L-thyroxine on ability and behavior in children with congenital hypothyroidism.

METHODS

An existing database, involving a large cohort of children with congenital hypothyroidism detected by neonatal screening, was analyzed retrospectively. There were 94 children: 89 were assessed at age 7 years for intelligence and selective cognitive abilities, and 87 at age 8 years for behavior, achievement, and selective abilities.

RESULTS

Subjects were stratified by median split into low and high starting dose groups. The high-dose group performed better on indexes of intelligence, verbal ability, and memory but had more behavior problems reflecting increased anxiety, social withdrawal, and poorer concentration. The dose of L-thyroxine at age 8 years was negatively correlated with memory task performance.

CONCLUSION

A higher starting dose of L-thyroxine is beneficial for subsequent intellectual outcome in children with congenital hypothyroidism but may be associated with internalizing behavior problems.

Persistent cognitive defects after corrected hypothyroidism

The authors present a case history in which cognitive defects caused by hypothyroidism persist after the patient has been rendered euthyroid. Concentration, recall and short-term memory appear to be most severely affected. The scarce literature on the subject is reviewed.

Thyrotropin response to TRH stimulation in depressed patients with autoimmune thyroiditis

Two thyroid axis findings are often reported in depressed patients: autoimmune thyroiditis and abnormal thyrotropin (thyroid stimulating hormone, TSH) responses to thyrotropin-releasing hormone (TRH). The TSH response to TRH can be exaggerated, suggesting subclinical hypothyroidism; it can alternatively be blunted, for reasons poorly understood. We selected 28 women who had been found to have major depression for TRH testing. Fifteen patients had autoimmune thyroiditis and 13 had diffuse nontoxic goiter. The endocrinological diagnoses were verified by fine-needle aspiration biopsy and cytological assessment. Patients with overt hypothyroidism and hyperthyroidism were excluded from the study. There were no differences between the two groups in total triiodthyronine and thyroxine plasma levels or severity of depression. In the autoimmune group, basal TSH and Dmax TSH tended to be higher (p < 0.1); peak TSH was significantly higher (p < 0.05), suggesting that the prevalence of subclinical hypothyroidism was also higher. Blunted TSH responses were found about as often in one group as the other.

Spectrum of quality of life impairment in hypothyroidism

The aim of this study is to evaluate the frequency and relative importance of different aspects of health related quality of life (HRQOL) impairment in patients with hypothyroidism. A survey of 200 patients with treated hypothyroidism was undertaken. Patients were identified and questionnaires distributed through family physicians, endocrinologists, and regional branches of the Thyroid Foundation of Canada. Frequency of importance of patients' symptoms attributed to hypothyroidism and resolved or improved with treatment were measured. Establishing the wide variety of patient-specific complaints associated with hypothyroidism provides guidance for clinicians dealing with hypothyroid patients, and investigators interested in HRQOL impairment in these patients.

Intellectual development at 10 years in early treated congenital hypothyroidism

Fifty nine children born between 1978 and 1981 with congenital hypothyroidism detected by neonatal screening were assessed at 10 years using the Wechsler intelligence scale for children, together with 59 matched classroom controls. Thirty one children with severe hypothyroidism who had pretreatment plasma thyroxine concentrations of 40 nmol/l or less had a mean (SD) full scale IQ score of 104.7 (15.1), compared with a mean (SD) score of 114.6 (16.3) for the 28 less severely affected children who had pretreatment thyroxine levels greater than 40 nmol/l, and mean (SD) scores of 114.5 (12.8) and 114.8 (13.8) respectively for the 31 and 28 control children. In the hypothyroid children the IQ scores at 10 years were closely related to the IQ scores at 5 years and at 3 years. It is concluded that the deficit in IQ score found at 3 and 5 years in children with severe hypothyroidism is still evident at the age of 10 years.

Relation between biochemical severity and intelligence in early treated congenital hypothyroidism: a threshold effect

OBJECTIVES

To assess whether early treatment of congenital hypothyroidism fully prevents intellectual impairment.

DESIGN

A national register of children with congenital hypothyroidism who were compared with unaffected children from the same school classes and matched for age, sex, social class, and first language.

SETTING

First three years (1982-4) of a neonatal screening programme in England, Wales, and Northern Ireland.

SUBJECTS

361 children with congenital hypothyroidism given early treatment and 315 control children.

MAIN OUTCOME MEASURES

Intelligence quotient (IQ) measured at school entry at 5 years of age with the Wechsler preschool and primary scale of intelligence.

RESULTS

There was a discontinuous relation between IQ and plasma thyroxine concentration at diagnosis, with a threshold at 42.8 nmol/l (95% confidence interval 35.2 to 47.1 nmol/l). Hypothyroid children with thyroxine values below 42.8 nmol/l had a mean IQ 10.3 points (6.9 to 13.7 points) lower than those with higher values and than controls. None of the measures of quality of treatment (age at start of treatment (range 1-173 days), average thyroxine dose (12-76 micrograms in the first year), average thyroxine concentration during treatment (79-234 nmol/l in the first year), and thyroxine concentration less than 103 nmol/l at least once during the first year) influenced IQ at age 5.

CONCLUSIONS

Despite early treatment in congenital hypothyroidism the disease severity has a threshold effect on brain development, probably determined prenatally. The 55% of infants with more severe disease continue to show clinically significant intellectual impairment; infants with milder disease show no such impairment. The findings predict that 10% of early treated infants with severe hypothyroidism, compared with around 40% of those who presented with symptoms in the period before screening began, are likely to require special education.

The thyroid and mixed affective states

The relationship between Grade II subclinical hypothyroidism and mixed affective states were examined in a cohort of 66 patients with bipolar affective disorder. The overall frequency of Grade II subclinical hypothyroidism was 20%. There was no difference in frequency of subclinical hypothyroidism or in mean thyroid hormone levels between the mixed state and non-mixed-state group.

Correlation of cognitive test scores and adequacy of treatment in adolescents with congenital hypothyroidism. New England Congenital Hypothyroidism Collaborative

PURPOSE

To measure the frequency of noncompliance and its possible effect on school achievement test and cognitive test scores in our older patients with congenital hypothyroidism.

METHODS

Fifty patients born from 1976 through 1978 were studied at home when they were 14 years of age. Each patient was given a battery of psychometric and school achievement tests, and blood for hormonal assays was drawn without forewarning from 36 of the patients on the day of examination. Efforts were made to improve control after the second year. During the third summer the tests were repeated in 25 of the 29 patients who had been tested at the age of 14; thyrotropin and thyroxine concentrations were measured in 23 of these 25 patients.

RESULTS

At the age of 14 years 16 of the 36 children had poorly controlled hypothyroidism, as defined by thyrotropin values greater than 15 mU/L. Of these 16 patients, 13 also had thyroxine concentrations of less than 85 nmol/L (6.6 micrograms/dl). A second examination at 15 or 16 years of age disclosed significant improvements in hormonal concentrations without changes in thyroxine dosage. Poor control was demonstrated on at least one occasion in 74% of 27 children older than 12 years of age who had 3 to 8 thyrotropin measurements during a period of 9 months. Cognitive test results in the patients did not differ from those in control subjects or from previous test results in the same children. The improved hormonal concentrations at the age of 15 or 16 years, however, were accompanied by significant improvement in cognitive test results; mean IQ increased from 106 to 112 (p = 0.002). Patients with greater improvement in hormonal values had significantly greater improvement in IQ.

CONCLUSIONS

The prevalence of noncompliance in the adolescent children of our cohort with congenital hypothyroidism was high. Subsequent improvement in thyroid control was associated with significant improvement in psychometric test scores.

Thyroid function screening in newly admitted psychiatric inpatients

Thyroid function tests (T4, T3RU, free thyroxine index) were performed upon admission in 269 acute psychiatric patients during a 2-year period. Thyroid disease was detected in 3% and euthyroid abnormalities in 9.3%. T4 and free thyroxine index were significantly lower in depressed patients than those with mania or schizophrenia. The rate of abnormal thyroid tests was lower in this study than in previously reported surveys of psychiatric admissions. Laboratory techniques or differences in population may be responsible for the difference. The differences in thyroid function test values between psychiatric diagnoses are relatively new findings, and appear worthy of investigation.