Influences of thyroid stimulating hormone on cognitive functioning in very old age.
ABSTRACT This study investigated the relationship of thyroxine (T4) and thyroid stimulating hormone (TSH) within normal ranges to cognitive performance in very old age. The participants (N = 200) were selected from a population-based study of nondemented persons aged 75 to 96 years (M = 83.9 years). Tasks assessing episodic memory, verbal fluency, visuospatial ability, short-term memory, and perceptual-motor speed were examined. Results indicated that T4 was unrelated to performance. However, TSH was positively related to episodic memory performance, and the effects were independent of the influence of age, level of education, and depressive mood symptoms. There was no reliable effect of TSH on verbal fluency, short-term memory, perceptual-motor speed, or visuospatial functioning. The influence of TSH on episodic memory was interpreted in terms of its potential effects on encoding and consolidation processes.
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ABSTRACT: Context: Several studies have evidenced the association between subclinical hyperthyroidism and cognitive impairment in the elderly. However, the effect of long-term TSH suppressive therapy on the cognitive function in elderly patients with differentiated thyroid carcinoma (DTC) is still unclear. Objective: Our aim was to investigate the effect of long-term TSH suppression on the cognitive function of elderly patients with DTC. Design, setting, and participant: A cross-sectional case-control study including 50 DTC patients aged 65 years or older (mean age = 70.9 ± 5.0 years) who have received a TSH suppressive therapy for at least 5 years and 90 control subjects matched for age, sex, education period, and depressive mood was conducted. Major outcome measure: Comprehensive cognitive domains were compared between the patient and control groups. The association between serum thyroid hormone concentration and cognitive function was investigated. Results: The patient group had higher serum free T4 levels and suppressed TSH levels compared to the control group. Age, sex, education period, Geriatric Depression Scale (GDS-K), and Cumulative Illness Rating Scale (CIRS) were not different between the two groups. All assessed neuropsychiatric tests were comparable in both groups. In the patient group, those with higher serum free T4 levels performed better on Mini-Mental State Examination and Trail Making Test A. The association between serum free T4 and Trail Making Test A was maintained after adjusting for age, education period, GDS-K, and CIRS. In the control group, serum free T4 and TSH levels were not associated with any of the assessed cognitive domains. Conclusion: Our results demonstrated the safety of long-term TSH suppression on the cognitive function in elderly DTC patients. Furthermore, the positive correlations between serum free T4 levels and some cognitive domains suggest the potential beneficial effects of exogenous levothyroxine on the cognitive function of patients who lack endogenous thyroid hormone.Journal of Clinical Endocrinology & Metabolism 07/2014; 99(10):jc20134454. DOI:10.1210/jc.2013-4454 · 6.31 Impact Factor
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ABSTRACT: Attention disorders are common symptoms in patients with untreated hyperthyroidism. Nevertheless, it is unknown whether they represent a global attention deﬁcit or selective impairment of attention networks. Thirty-seven patients with hyperthyroidism were recruited and underwent the Attention Network Test (ANT), which provided measures of three independent attention networks (alerting, orienting and executive control), before being treated with methimazole. This study demonstrated that patients with untreated hyperthyroidism had significant deficits in the alerting and executive control networks. Interestingly, a significant positive association was also found between T4 level and the value of the executive network in patients with hyperthyroidism. These results suggest that the patients with hyperthyroidism may not just exist a specific impairment of attention networks, and there was some relationship between the level of T4, not T3 or TSH, and the value of the executive control network in patients with hyperthyroidism.Neuroscience Letters 05/2014; DOI:10.1016/j.neulet.2014.05.016 · 2.06 Impact Factor