system
Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, RESULTS. Meshes: Attention Deficit Disorder with Hyperactivity, Child, Preschool, Cognition Disorders, Cross-Sectional Studies, Female, Humans, Linear Models, Male, Multivariate Analysis, Neuropsychological Tests, Reference Values, Thyroid Function Tests, Thyrotropin, Thyroxine, Triiodothyronine.
user
Is tSH concentration within the normal range associated with cognitive function and ADHD symptoms in healthy preschoolers? Context: 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. 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.
assistant
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. Final Decision: yes