The association of thyroid stimulating hormone levels with cognitive function and depressed mood: the Rancho Bernardo study

The association between depression and thyroid function

Background

Emerging evidence indicated that depression is currently one of the most burdensome diseases worldwide, and it can lead to a variety of functional physical impairments. However, the studies estimated the association between depression and thyroid function remain sparse. We aimed to investigate the association between depression and thyroid function in the American population.

Methods

A cross-sectional analysis was performed using the data from the National Health and Nutrition Examination Survey conducted from 2007 to 2012. In the 12,502 adults aged 20-80 years, weighted linear regression models and multiple logistic regression models were applied to evaluate the association between depression and thyroid function indicators. The thyroid indicators investigated were mainly free thyroxine (FT4), total T4 (TT4), free triiodothyronine (FT3), total T3 (TT3), thyroid-stimulating hormone (TSH), and antithyroperoxidase antibody (TPOAb), thyroglobulin (Tg) and antithyroglobulin antibody (TgAb).

Results

The final results were reached after adjusting for various confounding factors. In the stratification analysis of subgroups divided by age, depression was significantly negatively correlated with FT4, FT3, and TT3 in both younger adults (p = 0.00122, p < 0.00001, and p = 0.00003) and older adults (p = 0.00001, p = 0.00004, and p < 0.00001). In contrast, depression was significantly negatively correlated with TT4 and Tg in older adults (p = 0.00054, p = 0.00695) and positively correlated in younger adults (p = 0.01352, p < 0.00001). The subgroup analysis by gender revealed that depression was significantly negatively correlated with FT4, FT3, and TT3 in both adult males (p = 0.0164, p = 0.0204, and p = 0.0050) and adult females (p ≤ 0.0001, p < 0.0001, and p < 0.0001), which was more prominent in females. The positive correlation between depression symptoms and TPOAb was only found in adult females (p = 0.0282) and younger adults (p = 0.00488).

Conclusion

This study confirmed a significant correlation between depressive and thyroid function and it varied among different genders or age. In the future, more prospective studies are needed to reveal these findings and confirm a causal relationship between them.

Gender Differences of Antioxidant System and Thyroid Function in Depressed Adolescents with Non-Suicidal Self-Injury

Purpose

The aim of our study was to explore the relation between serum levels of non-enzymatic antioxidants, thyroid function with the risk of non-suicidal self-injury (NSSI) in depressed adolescents.

Patients and Methods

We retrospected the electronic records of 454 hospitalized patients aged 13-17 years old with a diagnosis of major depressive disorder (239 patients with NSSI and 215 subjects without NSSI), and collected their demographic and clinical information, including serum levels of total bilirubin (Tbil), uric acid (UA), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH).

Results

The incidence of NSSI was 52.6% among depressed adolescents aged 13-17, 57.1% in female and 38.5% in male. After using the propensity scoring method to exclude the influence of age between the two groups, it was found that patients with NSSI showed lower levels of Tbil (P=0.046) and UA (P=0.015) compared with those without NSSI. Logistic regression results showed that serum UA was associated with NSSI behavior in female patients (OR=0.995, 95% CI: 0.991-0.999, P=0.014), and TSH was associated with NSSI in male participants (OR=0.499, 95% CI: 0.267-0.932, P=0.029).

Conclusion

Female and male may have different pathological mechanisms of NSSI. NSSI is more likely to be related to antioxidant reaction in female adolescent patients, while more likely to be related to thyroid function in male depressed adolescent patients.

Depressive symptoms, thyroid hormone and autoimmunity in a population-based cohort from Sardinia

OBJECTIVE

To evaluate the association between depressive symptoms and thyroid autoimmunity, and the effect of thyroid hormone on the risk of depression.

METHODS

We included 3138 individuals from SardiNIA project, none of whom was taking thyroid medication and antidepressants. Thyrotropin (TSH), free thyroxine (FT4), and antibodies against thyroperoxidase (TPOAb) were measured in all the sample. Depressive symptoms were assessed with Center for Epidemiologic Studies Depression Scale (CES-D).

RESULTS

We found no association between TPOAb and depressive symptoms and no linear association between TSH or FT4 levels and depressive symptoms. However, individuals in the lowest and highest FT4 quintiles showed a higher CES-D score compared to individuals in the middle quintile. In addition, participants in the lowest and highest FT4 quintiles had an increased risk of CES-D≥16 with odds ratios of 1.44 (95% CI=1.09-1.89) and 1.33 (95% CI=1.01-1.77), respectively.

LIMITATIONS

Cross-sectional design of the study.

CONCLUSIONS

A U-shaped relation was found between FT4 and depressive symptoms: compared to average FT4 values, both high and low thyroid function was associated with more depressive symptoms. Further studies are necessary to determine the exact cause-effect relation of this association.

Depressive symptoms in patients with subclinical hypothyroidism--the effect of treatment with levothyroxine: a double-blind randomized clinical trial

Despite the increasing evidence for relationships between thyroid dysfunction and neuropsychiatric alterations, the effect of treatment of thyroid disease on various clinical psychiatric outcomes is controversial. The purpose of this study was to investigate the effect of levothyroxine treatment on depressive symptoms in subjects with subclinical hypothyroidism. A randomized double-blind placebo-controlled clinical trial was performed. Sixty subjects (51 females and 9 males) with subclinical hypothyroidism were enrolled. Beck Depression Inventory was completed for all participants at the beginning of the study and 12 weeks after enrollment. The intervention and control groups received levothyroxine and placebo, respectively, for 12 weeks. There were no statistical differences in the total depression score and its subscales between the two groups at the beginning of the study. The Beck Depression Inventory score decreased from 16.79 ± 13.25 to 12.37 ± 10.01 (p value = 0.04) in the intervention group. The change in score was not significant for the control group (13.77 ± 11.71 to 11.86 ± 10.71; p value= 0.16). The affective subscale of Beck Depression Inventory did not change after 12 weeks of treatment with levothyroxine, while somatic subscale remarkably improved in the intervention group (p value = 0.02). This study showed the efficacy of treatment of subclinical hypothyroidism in people with levothyroxine in relation to depressive symptoms.

Hypothyroidism and depression

BACKGROUND

A relationship between hypothyroidism and depression has been assumed for many years; however, the true nature of this association has been difficult to define with many conflicting studies. In recent years, our knowledge in this area has increased significantly with large cohort studies and genetically driven studies being published.

OBJECTIVES

We reviewed the literature on thyroid function and depression to determine if this relationship has been clarified.

METHODS

We performed a search on the Pubmed database using the terms 'thyroid
 ' and 'mental health
 ', 'depression
 ' and 'well-being
 '.

RESULTS

Large epidemiological studies generally suggest no association between thyroid function and depression in subjects without thyroid disease. Subjects on thyroxine have poorer psychological well-being than subjects with no thyroid disease even if biochemically euthyroid, they also show an association between thyroid function and well-being. Whilst there is some early evidence that genetic factors can influence well-being on thyroxine and response to combination therapy, there is also evidence to suggest that much morbidity on thyroxine may be due to initial misdiagnosis and mis-attribution of symptoms.

CONCLUSION

Despite the large number of studies, the relationship between thyroid function and depression remains poorly defined. Clarification of the proportion of subjects on thyroxine incorrectly may assist the large (perhaps genetically driven) studies needed to move forward in this area, as it is expected that they cloud the results.

Thyroid hormones are associated with cognitive function: moderation by sex, race, and depressive symptoms

CONTEXT

Recent evidence indicates that thyroid hormones may be closely linked to cognition among adults.

OBJECTIVE

We investigated associations between thyroid hormones and cognitive performance, while testing effect modification by sex, race, and elevated depressive symptoms (EDS).

DESIGN

This cross-sectional study used extensive data from the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study.

SETTING

The study was conducted in Baltimore, Maryland, from 2004 to 2009.

PARTICIPANTS

PARTICIPANTS were U.S. adults aged 30 to 64 years. The sample size ranged from 1275 to 1346.

MAIN OUTCOME MEASURES

Outcomes included 13 cognitive test scores spanning domains of learning/memory, language/verbal, attention, visuo-spatial/visuo-construction, psychomotor speed, executive function, and mental status.

RESULTS

Within reference ranges and after Bonferroni correction, elevated free thyroxine (fT4) was associated with better performance on tests of visuo-spatial/visuo-construction ability (overall, women, and African Americans) and learning/memory (women and African Americans), whereas a higher total thyroxine (tT4) level was associated with better performance in the domain of psychomotor speed (individuals without EDS) and higher levels of both fT4 and tT4 were linked to better language/verbal test performance among men. In contrast, higher T3(% uptake) was related to better performance on tests of visuo-spatial/visuo-construction ability and psychomotor speed among whites. When the above reference range was compared within the overall population and after Bonferroni correction, a within reference range fT4 was linked to better performance on visuo-spatial/visuo-constrution ability and psychomotor speed, whereas a below normal range TSH level (compared with the reference range) was linked to better performance in domains of psychomotor speed and attention.

CONCLUSIONS

Thyroid hormones and cognition are closely linked differentially by sex, race, and EDS status.

Subclinical hypothyroidism, mood, and cognition in older adults: a review

OBJECTIVES

To perform a critical review of the literature on the mood and cognitive changes associated with subclinical hypothyroidism (SCH), with an emphasis on older adults. To evaluate these data against the Consensus Statement on the management of SCH from the American Association of Clinical Endocrinologists, the American Thyroid Association, and The Endocrine Society.

METHOD

A comprehensive literature review.

RESULTS

Subclinical hypothyroidism may be associated with an increased risk of mood and cognitive dysfunction, although the strength of this association and the efficacy of replacement hormone therapy require further investigation.

CONCLUSION

It remains unclear whether SCH leads to significant mood and cognitive impairments in most older patients. More research is required to determine the nature and extent of this association and whether thyroid hormone replacement therapy is appropriate and effective in treating SCH-associated neurobehavioral impairments.

Higher free thyroxine levels predict increased incidence of dementia in older men: the Health in Men Study

CONTEXT

Both hypothyroidism and subclinical hyperthyroidism hinder cognitive function.

OBJECTIVE

We aimed to determine whether more subtle alterations of thyroid hormone levels predict increased incidence of dementia in aging men.

PARTICIPANTS AND DESIGN

Community-dwelling men aged 70-89 yr participated in this prospective longitudinal study.

MAIN OUTCOME MEASURES

The Standardized Mini-Mental State Examination was performed at baseline (2001-2004), and circulating TSH and free T(4) (FT(4)) were assayed. Men with known thyroid disease or dementia, or Standardized Mini-Mental State Examination scores below 24 were excluded from follow-up. New-onset dementia, defined by International Classification of Disease (ICD) codes, was ascertained using data linkage (2001-2009).

RESULTS

During follow-up, 145 of 3401 men (4.3%) were diagnosed for the first time with dementia. Men who developed dementia had higher baseline FT(4) (16.5 ± 2.2 vs. 15.9 ± 2.2 pmol/liter, P = 0.004) but similar TSH (2.2 ± 1.4 vs. 2.3 ± 1.6 mU/liter, P = 0.23) compared with men who did not receive this diagnosis. After adjusting for covariates, higher FT(4) predicted new-onset dementia (11% increased risk per 1 pmol/liter increase in FT(4), P = 0.005; quartiles Q2-4 vs. Q1: adjusted hazard ratio = 1.76, 95% confidence interval = 1.03-3.00, P = 0.04). There was no association between TSH quartiles and incident dementia. When the analysis was restricted to euthyroid men (excluding those with subclinical hyper- or hypothyroidism), higher FT(4) remained associated with incident dementia (11% increase per unit increment, P = 0.03; Q2-4 vs. Q1: adjusted hazard ratio = 2.02, 95% confidence interval = 1.10-3.71, P = 0.024).

CONCLUSIONS

Higher FT(4) levels predict new-onset dementia in older men, independently of conventional risk factors for cognitive decline. Additional studies are needed to explore potential underlying mechanisms and to clarify the utility of thyroid function testing in older men at risk of dementia.

Thyroid disease and mental disorders: cause and effect or only comorbidity?

PURPOSE OF REVIEW

To discuss the effects of thyroid dysfunction and thyroid autoimmunity on mental symptoms and disorders in patients with thyroid disease with reference to recent epidemiological, clinical, and genetic findings.

RECENT FINDINGS

During brain development, iodine deficiency, maternal thyroid dysfunction, and neonatal thyroid malformations together with genetic factors contribute to neurological deficit. Most adults with thyroid dysfunction will develop mental symptoms. In hyperthyroidism, adrenergic hyperactivity is a major cause of psychiatric symptoms, and beta-adrenergic antagonists are effective treatment. Most patients with severe hypothyroidism will also demonstrate mental symptoms; however, causality is not so evident as in hyperthyroidism. Polymorphism in deiodinase genes and in transporter genes appears to make an important contribution to the presentation of mental symptoms as well as to the outcome of treatment of hypothyroidism. A thyroid autoimmunity process may by itself contribute to mental symptoms in vulnerable patients. Data from epidemiological studies provide conflicting evidence as to associations between thyroid disorders and mental symptoms.

SUMMARY

In the adult brain, compared with the developing brain, brain-thyroid relationships are less apparent but still important. Adrenergic hyperactivity is a major cause of psychiatric symptoms in hyperthyroidism. Genetic factors contribute to the development and treatment outcome of mental disorder in hypothyroidism.