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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- "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. "
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
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- "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). "
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.Neurobiology of aging 07/2011; 33(8):1730-43. DOI:10.1016/j.neurobiolaging.2011.05.008 · 4.85 Impact Factor
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- "In the Rotterdam Study, subclinical hyperthyroidism at baseline was also seen to give a 3.5 fold increase in risk for AD and dementia after a 2 year follow-up (Kalmijn et al., 2000). Another study (Wahlin et al., 1998), of the oldest old without dementia, a psychiatric diagnosis or overt thyroid disease, showed a similar association between having low-normal TSH levels and worse episodic verbal memory. In a follow-up study of this cohort (Wahlin et al., 2005), the drop in TSH levels over 6 (but not 3) years predicted decline in verbal memory, but not in other cognitive functions. "
ABSTRACT: Hypothyroidism and subclinical hyperthyroidism have both been associated with cognitive impairment and dementia. The association between thyroid stimulating hormone (TSH), free thyroid hormone or thyroxine (FT4) levels and cognition was investigated at baseline and after a 2 year follow-up in 1047 participants over 64 years of age, without physical frailty or severe cognitive impairment at baseline. Results indicated that high log transformed TSH levels were associated with lower MMSE performance (B=-0.24 (S.E.=0.09), 95% CI=-0.41 to -0.07) at baseline, independent of FT4, age, sex, education and mood, and, in separate analyses, cardiovascular (risk) factors. Importantly, half of all hypothyroid cases were untreated and unaware of having this disorder. In analyses which excluded cases with thyroid disorders, stroke and those suspected of possible dementia/cognitive impairment (MMSE less than 25) or psychiatric mood disorders at baseline, high-normal FT4 levels were associated with worse MMSE performance and a greater risk for a drop of at least 4 points on the MMSE after 2 years (per pmol/l O.R.=1.13, 95% C.I.=1.03-1.22). In conclusion, elderly patients with cognitive impairment should always be assessed for hypothyroidism. It is unclear why high normal FT4 levels were independently associated with accelerated cognitive decline in those without overt thyroid disease. Other studies found that thyroxine can generate oxidative stress and damage neurons. Treatment with thyroxine in those without thyroid disease (as is sometimes done in anti-ageing clinics) is thus not recommended on the basis of these data and the optimal therapeutic level in the elderly may be lower than is assumed.Psychoneuroendocrinology 08/2008; 33(7):1013-22. DOI:10.1016/j.psyneuen.2008.05.008 · 5.59 Impact Factor