Influences of Thyroid Stimulating Hormone on Cognitive Functioning in Very Old Age
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.
Available from: Alfonso Gutierrez-Zotes
- "Studies conducted on cognition and thyroid function are very scarce and have found contradictory results. Both TSH and FT4 levels were associated with better verbal learning and memory in the elderly (Wahlin et al., 1998). Another study reported that high levels (but within the normal range) of triiodothyronine (FT3) were associated with poorer performance on tests of executive function and processing speed in healthy women; FT4 levels were not associated with a poorer cognition (Ewins et al., 1991). "
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ABSTRACT: Subjects with a psychotic disorder show mild to moderate cognitive impairment, which is an important determinant of functional outcome. The underlying biological process of cognitive impairment in psychosis is unclear. We aimed to explore whether hypothalamic-pituitary-thyroid axis hormones or thyroid autoimmunity modulate cognitive functioning in subjects with early psychosis.
We studied 70 patients with a psychotic disorder (<3years of illness) and a control group of 37 healthy subjects (HS). Plasma levels of thyroid-stimulating hormone (TSH), free thyroxine (FT4) and thyroid-peroxidase (TPO-Abs) and thyroglobulin antibodies (TG-Abs) were determined. Cognitive assessment was performed with the MATRICS Cognitive Consensus Cognitive Battery. We also explored the relationship between thyroid variables and cognition in three subgroups of psychotic patients: psychosis not otherwise specified, affective psychosis (bipolar disorder or schizoaffective disorder) and non-affective psychosis (schizophrenia or schizophreniphorm disorder).
In patients with early psychosis, higher FT4 levels (but not TSH or thyroid antibodies) were associated with better cognitive performance in attention/vigilance and overall cognition. The relationship between FT4 levels and the attention/vigilance domain remained significant in a multivariate analysis after adjusting for education level, age, gender, substance use, and benzodiazepine and antipsychotic treatments. We did not find a significant association between FT4 and cognitive performance in HS. In the exploratory analysis by psychotic subtypes, subjects with affective psychosis had increased FT4 levels and better cognitive profile than those with non-affective psychosis.
Our study suggests that FT4 levels are associated with cognitive abilities (attention/vigilance and overall cognition) in individuals with early psychosis.
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Available from: Jin Fan
- "De Jong et al.  also reported that higher T4 levels, but not TSH, were associated with an increased risk of dementia. However, Wahlin et al.  found an association between TSH, but not T4, and episodic memory and Livner et al.  found that TSH levels were related to prospective memory function , while T4 levels were unrelated to their deficits. In our study, it is likely that excessive T4 could induce executive network disorders by regulating the metabolism of the midfrontal brain areas and dopamine. "
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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.
Available from: May A Beydoun
- "Overall, a limited number of cross-sectional, cohort, and experimental studies have examined the effect of thyroid function on various cognitive outcomes. Out of 10 crosssectional studies (Almeida et al., 2007; Cárdenas-Ibarra et al., 2008; Ceresini et al., 2009; Kramer et al., 2009; Prinz et al., 1999; Samuels et al., 2007b; Stern et al., 2004; Stuerenburg et al., 2006; Wahlin et al., 1998; Wu et al., 2006), 6 suggested that either hypothyroidism or hyperthyroidism may be linked to adverse cognitive outcomes, 2 had mixed results (Wahlin et al., 1998; Wu et al., 2006), and 2 had no significant results (Almeida et al., 2007; Kramer et al., 2009). Out of 4 cohort studies (de Jong et al., 2009; Gussekloo et al., 2004; Hogervorst et al., 2008; Volpato et al., 2002), 3 suggested positive (de Jong et al., 2009; Hogervorst et al., 2008; Volpato et al., 2002), and 1 suggested negative findings (Gussekloo et al., 2004). "
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ABSTRACT: Neuroanatomical connections point to possible interactions between areas influencing energy homeostasis and those influencing cognition. We assessed whether serum leptin, thyroxine, and thyroid stimulating hormone (TSH) levels are associated with and interact to influence cognitive performance among US adults. Data from the National Health and Nutrition Examination Survey III (1988-1994) were used. Measures included a battery of neuropsychological tests and serum leptin, thyroxine, and TSH levels (20-59-year-old: n = 1114-2665; 60-90-year-old: n = 1365-5519). Among those 20-59-year-old, the middle tertile of leptin (vs. first tertile) was inversely related to the number of errors on the symbol digits substitution test. Increased thyroxine level was associated with a poorer performance on the serial digits test in the 20-59-year-old, but a better performance on the math test in 60-90-year-old group. TSH was associated with poor performance on various tests in the 20-59-year-old, but better performance in the 60-90-year-old group. Significant antagonistic interactions were found in both age groups between thyroxine, TSH, and leptin for a number of tests, including between leptin and thyroxine in the 60-90-year-old group in their association with word recall-correct score. We found significant associations of our main exposures with cognitive function among US adults, going in opposite directions between age groups in the cases of thyroid hormonal levels, as well as some interactive effects between exposures. It is important to conduct prospective cohort studies to provide further insight into potential interventions that would assess interactive effects of various hormonal replacement regimens.
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