Individuals with congenital hypothyroidism (CH), even those diagnosed and treated early, experience selective cognitive deficits, the most striking of which involves the visuocognitive domain. However, the range and nature of their visuocognitive disturbances is not fully understood. We assessed a range of higher-order visuocognitive abilities in 19 children and adolescents with CH and 19 age- and sex-matched typically developing peers (TD) using a battery of neuropsychological tests and a novel self-report measure of sense of direction. CH scored lower than TD on direct tests of visuocognitive function (judging line orientation, parts-to-whole localization, copying three-dimensional block towers, discriminating designs, and matching unfamiliar faces in ¾ profile-view) as well as on self-reported problems in spatial ability. Visuocognitive problems were not global as CH and TD did not differ at copying two-dimensional block designs, mentally rotating and matching abstract shapes, or at matching unfamiliar front-view faces, design features, or designs that engaged either figure-ground segregation, visual constancy, or closure. Early and concurrent thyroid stimulating hormone (TSH) levels were associated with visuocognitive ability, although attention and working memory were not. Individuals with CH exhibit selective visuocognitive weaknesses, some of which are related to early and concurrent TSH levels. (JINS, 2013, 19, 1–9)

Memory deficits and hippocampal abnormalities have been described in individuals with thyroid hormone (TH) insufficiencies; however, no study has yet examined their autobiographical memory (AM) abilities, which are known to be compromised by hippocampal damage. Investigations in adults have shown that AM consists of both episodic and semantic components and that the hippocampus is preferentially involved in episodic AM. The present study used the Children's Autobiographical Interview (CAI) to study episodic and semantic AM in 79 children aged 9 to 14 years, including 26 with early-treated congenital hypothyroidism (CH), 23 born to women with inadequately treated hypothyroidism during pregnancy (HYPO), and 30 typically developing controls. Results showed that relative to controls, CH and HYPO groups both exhibited weaknesses in episodic AM, but not semantic AM. In particular, CH and HYPO groups showed difficulty in recalling event details (i.e., the main happenings) and visual details from past experiences. Overall, this study highlights the importance of TH for early neurodevelopment and provides critical new insight into the effects of early treated TH deficiency on long-term memory performance. Furthermore, the present study indicates that the CAI is an effective tool for investigating episodic AM impairment in clinical pediatric populations. (JINS, 2013, 19, 1–11)

Congenital hypothyroidism is a pediatric endocrine disorder caused by insufficient endogenous thyroid hormone production. Children with congenital hypothyroidism have difficulties with episodic memory and abnormalities in hippocampal structure, suggesting deficient hippocampal functioning. To assess hippocampal activation in adolescents with congenital hypothyroidism (N = 14; age range, 11.5–14.7 years) compared with controls (N = 15; age range, 11.2–15.5 years), a functional magnetic resonance imaging visuospatial memory task was used. In this task, participants had to decide if object pairings were novel or were previously studied or if object pairs were in the same location as they were at study or had switched locations. Despite no group differences in task performance, adolescents with congenital hypothyroidism showed both increased magnitude of hippocampal activation relative to controls and bilateral hippocampal activation when only the left was observed in controls. Furthermore, the increased activation in the congenital hypothyroidism group was correlated with the severity of the hypothyroidism experienced early in life. These results suggest that perinatal deprivation of thyroid hormone has longstanding effects on hippocampal function and may account for memory problems experienced by adolescents with congenital hypothyroidism. (JINS, 2012, 18, 49–56)

Recent studies suggest that children with different etiologies of attention disorder also differ as to the types of errors they make on attention tasks. Because these errors are reflective of the core deficits underlying their attention problems, we sought to compare error patterns in children with different attention disorders. Studied were 144 children aged 7–12 years, 43 with attention deficit hyperactivity disorder (ADHD), 35 with congenital hypothyroidism (CH), and 68 controls. Two variations of the continuous performance task (CPT) that differed in demands on inhibitory control and memory were used. One variation, the CPT:A-not-X task, required subjects to observe a continuous stream of letters shown at different rates on the computer screen and respond to all stimuli except “X”. The other variation, the CPT:AX task, required them to respond whenever a specified combination of letter such as “A” followed by “X” appeared on the screen. On the CPT:A-not-X task, children with ADHD differed from controls in commission errors, signifying difficulty with inhibitory control, whereas children with CH differed in perceptual sensitivity or signal detection. Although the CH and ADHD groups both performed more poorly than controls on the CPT:AX task, children with CH made more errors to the first stimulus item, suggesting a problem holding information in memory, whereas children with ADHD made more errors to the second item, suggesting impulsivity. These results therefore signify the utility of these tasks in identifying the different mechanisms underlying the specific attention deficits of different groups of children.

Even though early treatment of congenital hypothyroidism (CH) with newborn screening prevents the mental retardation previously seen in cretinism, affected children still exhibit subtle persisting neurocognitive deficits. One of their commonest problems is poor attention, which reflects both early disease severity and later (high) circulating thyroid hormone levels. While attention is currently regarded as multicomponential in nature, with different processing components supported by different brain regions, the specific components of attention affected by CH have not been identified. In light of animal evidence showing that neonatal thyroid hormone deficiencies impede the neurodevelopment of structures important for selective aspects of attention, we proposed a multicomponential approach to study attention in children with CH. This was accomplished via retrospective analysis of existing data on adolescents with CH whose attention was previously evaluated using multiple tests. Results showed significantly poorer overall attention in CH than controls with differences occurring mainly on focus and inhibit indices. However, performance on various indices was associated with different disease parameters. Poor encode and focus were correlated with more severe hypothyroidism and a longer period of thyroid hormone insufficiency and poor select and shift with higher thyroid hormone levels at testing. These results signify that thyroid hormone is important for the development and later regulation of brain structures supporting distinct aspects of attention. (JINS, 2001, 7, 734–744.)

Visuospatial processing is accomplished in distinct neuroanatomic pathways. One such pathway, known as the where pathway, involves a dorsal route through magnocellular thalamic cells to occipital and parietal cortices and conveys location and motion information. A second pathway, known as the what pathway, involves a ventral route through parvocellular thalamic cells to occipital and temporal cortices and conveys color and form information. The where pathway is thought to be responsible for processing spatial relationships while the what pathway is responsible for object identification. Children with early-treated congenital hypothyroidism (CH) who exhibit selective visuospatial deficits may provide a good model to study the differential development of these pathways. Because children with CH lacked thyroid hormone at a time when needed by developing brain regions such as the parietal cortex, these children may be affected to a greater degree on tasks tapping where but not what pathway processing. We tested this hypothesis via retrospective analysis of their performance on 6 spatial tasks. Compared were 49 adolescents with CH and 49 matched control participants. On the basis of confirmatory factor analysis, tasks were assigned to either where or what pathway groupings. A repeated measures ANOVA showed the CH group was impaired relative to a normal comparison group only on where pathway tasks. Regression analyses indicated that severity of early hypothyroidism was the strongest predictor of where pathway processing but had no effect on what pathway tasks. It is concluded that thyroid hormone is required during late gestation and early life for the normal development of the where aspects of visuospatial processing. (JINS, 2001, 7, 556–562.)