Antithyroid antibodies in major depression

The Association Between Thyroid Stimulating Hormone and Depression: A Historical Cohort Study

OBJECTIVE

To investigate the association between thyroid-stimulating hormone (TSH) and clinically relevant depression (CRD) in a population-based study.

PATIENTS AND METHODS

Adult patients (≥18 years of age) who received care at Mayo Clinic in Rochester, Minnesota, and completed a TSH and Patient Health Questionnaire - 9 (PHQ-9) within 6 months of each other, between July 8, 2017, and August 31, 2021, were included. Demographics, medical comorbidities, thyroid function laboratory data, psychotropic medications, presence of primary thyroid disorder, thyroid hormone replacement (T4 and/or T3), and mood disorder diagnoses (using International Classification of Diseases, 10th version, Clinical Modifications codes) were extracted electronically. The primary outcome, CRD, was defined as a PHQ-9 score greater than or equal to 10. Logistic regression analysis was conducted to assess the association between TSH categories (low ≤0.3 mIU/L; normal >0.3-4.2 mIU/L; high >4.2 mIU/L) and CRD.

RESULTS

The cohort included 29,034 patients, mean age 51.4 years, 65% females, 89.9% White, and a mean body mass index of 29.9 kg/m2. The mean ± standard deviation for TSH was 3.0±8.5 mIU/L, and the mean PHQ-9 score was 6.3±6.2. After adjustment, the odds of CRD were significantly higher among the low TSH category (odds ratio, 1.37; 95% CI, 1.18-1.57; P<.001) compared with the normal TSH category, especially in people 70 years of age or younger compared with people older than 70 years of age. Subgroup analysis did not show an increase in odds of CRD among patients with subclinical/overt hypothyroidism/hyperthyroidism (after adjustment).

CONCLUSION

In this large population-based cross-sectional study, we report that low TSH was associated with higher odds of depression. Future longitudinal cohort studies are needed to investigate the relationship between thyroid dysfunction and depression as well as sex differences.

Depression and Autoimmune Hypothyroidism—Their Relationship and the Effects of Treating Psychiatric and Thyroid Disorders on Changes in Clinical and Biochemical Parameters Including BDNF and Other Cytokines—A Systematic Review

Various autoimmune diseases, including autoimmune hypothyroidism (AHT), are associated with a higher risk of developing mood disorders throughout life. Depression is accompanied by the changes in the levels of inflammatory and trophic factors, including interleukins (IL-1beta, IL-2, IL-6), interferon alpha (IFN-alpha), tumor necrosis factor alpha (TNF-alpha), C-reactive protein (CRP), and brain derived neurotrophic factor (BDNF). Disclosure of the relationship between the coexistence of depression and AHT indicates that the pathomechanism of depression may be related to the changes in the immune system, it is also possible that both conditions may be caused by the same immune processes. The above hypothesis is indirectly supported by the observations that the treatment with both antidepressants and levothyroxine leads to a decrease in the levels of proinflammatory cytokines with an increase in BDNF concentrations, simultaneously correlating with an improvement in the clinical parameters. However, so far there are no long-term studies determining the causal relationship between depression, thyroid autoantibodies, and cytokine profile, which could bring us closer to understanding the interrelationships between them and facilitate the use of an adequate pharmacotherapy, not necessarily psychiatric. We consider the above issues to be insufficiently investigated but of great importance. This article is an overview of the available literature as well as an introduction to our research project.

Hypothyroidism and Depression: Are Cytokines the Link?

CONTEXT

Primary hypothyroidism has been thought of as an inflammatory condition characterized by raised levels of cytokines such as C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). Depression is also well known to occur in hypothyroidism. Depression is also characterized by elevated inflammatory cytokines. We planned to study whether cytokines play an important part in linking these two conditions.

OBJECTIVES

(1) To know the prevalence of depression in overt hypothyroidism due to autoimmune thyroid disease. (2) To correlate the levels of inflammatory markers with the occurrence of depression. (3) To study the effect of levothyroxine on inflammatory markers and depression.

MATERIALS AND METHODS

In this longitudinal, case-controlled study, 33 patients with autoimmune hypothyroidism (thyroid-stimulating hormone >10 uIU/ml) were included with 33 age-, sex-, and body max index-matched healthy controls. Individuals were tested for Serum TNF-α, IL-6, high-sensitivity-CRP (hs-CRP). They were assessed for depression using Montgomery Asberg Depression Rating Scale (MADRS) and World Health Organization Quality of Life (QOL) Scale. Patients received L Thyroxine titrated to achieve euthyroidism and were reassessed for inflammatory markers and cognitive dysfunction.

RESULTS

Nineteen patients (57%) had mild to moderate depression (MADRS >11). After 6 months of treatment, eight patients (42%) had remission of depression with significant improvement in QOL scores (P < 0.05). TNF-α, IL-6, and hs-CRP were significantly elevated in patients compared with controls and reduced with therapy but did not reach baseline as controls. The change in inflammatory markers correlated with improvement in QOL scores in social and environmental domains (P < 0.01).

CONCLUSIONS

Primary autoimmune hypothyroidism is an inflammatory state characterized by elevated cytokines which decline with LT4 therapy. It is associated with depression and poor quality of life. Treatment of hypothyroidism results in alleviation of depression in the majority of patients. Similarly, patients with mild to moderate depression should be tested for hypothyroidism as simple treatment may ameliorate their depression and improves MADRS score and QOL.

Bipolar disorder and antithyroid antibodies: review and case series

Mood disorders and circulating thyroid antibodies are very prevalent in the population and their concomitant occurrence may be due to chance. However, thyroid antibodies have been repeatedly hypothesized to play a role in specific forms of mood disorders. Potentially related forms include treatment-refractory cases, severe or atypical depression, and depression at specific phases of a woman’s life (early gestation, postpartum depression, perimenopausal). With regard to bipolar disorder, studies of specific subgroups (rapid cycling, mixed, or depressive bipolar) have reported associations with thyroid antibodies. Offspring of bipolar subjects were found more vulnerable to develop thyroid antibodies independently from the vulnerability to develop psychiatric disorders. A twin study suggested thyroid antibodies among possible endophenotypes for bipolar disorder. Severe encephalopathies have been reported in association with Hashimoto’s thyroiditis. Cases with pure psychiatric presentation are being reported, the antithyroid antibodies being probably markers of some other autoimmune disorders affecting the brain. Vasculitis resulting in abnormalities in cortical perfusion is one of the possible mechanisms.

The Link between Thyroid Function and Depression

The relation between thyroid function and depression has long been recognized. Patients with thyroid disorders are more prone to develop depressive symptoms and conversely depression may be accompanied by various subtle thyroid abnormalities. Traditionally, the most commonly documented abnormalities are elevated T4 levels, low T3, elevated rT3, a blunted TSH response to TRH, positive antithyroid antibodies, and elevated CSF TRH concentrations. In addition, thyroid hormone supplements appear to accelerate and enhance the clinical response to antidepressant drugs. However, the mechanisms underlying the interaction between thyroid function and depression remain to be further clarified. Recently, advances in biochemical, genetic, and neuroimaging fields have provided new insights into the thyroid-depression relationship.

Peripheral thyroid dysfunction in depression

The involvement of the thyroid gland and thyroid hormones is generally believed to be important in the aetiopathogenesis of major depression. Major support comes from studies in which alterations in components of the hypothalamic-pituitary-thyroid (HPT) axis have been documented in patients with primary depression. However, screening thyroid tests are often routine and add little to the diagnostic evaluation. Overt thyroid disease is rare among depressed inpatients. The finding that depression often co-exists with autoimmune subclinical thyroiditis suggests that depression may cause alterations in the immune system, or that in fact it could be an autoimmune disorder itself. The outcome of treatment and the course of depression may be related to thyroid status as well. Augmentation of antidepressant therapy with the co-administration of thyroid hormones (mainly T3) is a well-documented treatment option for refractory depressed patients. Review of the literature suggests that there are no conclusive data on the role of thyroid function in depression. It is clear that depression is not characterised by an overt thyroid dysfunction, but it is also clear that a subgroup of depressed patients may manifest subtle thyroid abnormalities, or an activation of an autoimmune process. There is a strong possibility that the presence of a subtle thyroid dysfunction is a negative prognostic factor for depression and may demand specific therapeutic intervention.

Psychiatric symptoms and diagnoses in thyroid disorders: a cross-sectional study

Objective Endocrine dysfunction may produce symptoms that are difficult to distinguish from the clinical manifestations of psychiatric disorders. In particular, the function of the hypothalamic-pituitary-thyroidal axis is known to be associated with a number of psychiatric abnormalities, such as depression and anxiety. In this study, we tested the hypothesis that depression is more commonly encountered in hypothyroidism, while anxiety is more prevalent in hyperthyroidism. Additionally, we aimed to evaluate the correlations of the intensity of the psychiatric symptomatology in these patients with the specific parameters of thyroid function, such as levels of TSH, T3 and T4. Method Patients newly diagnosed as having thyroid disorders were included in the study. They were classified into five study groups (according to the results of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4) and autoantibody (anti-thyroglobulin antibodies and anti-microsomal antibodies) measurements): hypothyroid, hyperthyroid, subclinical hypothyroid, subclinical hyperthyroid, and euthyroid Hashimoto's thyroiditis. Psychopathological symptoms were evaluated on the 17-item Hamilton Rating Scale for Depression (HDRS), Brief Symptom Inventory (BSI), BSI Sub-scales and Hospital Anxiety and Depression Scale (HAD). Psychiatric diagnoses were performed using DSM-IV-SCID (Structured Clinical Interview for DSM). The relationship between the results of the psychiatric evaluation and thyroid function tests was assessed statistically by ANOVA and Pearson correlation tests. Results Eighty patients (68 female and 12 male), with a mean age of 42.5±13.4 years, were evaluated. A positive correlation between the total BSI scores and TSH levels (r = 0.65, P = 0.01) was noted in the hypothyroid (n=25) group. Hyperthyroid patients (n=22) showed a positive correlation between HDRS scores and fT4 levels (r = 0.62, P = 0.01). The BSI scores in hypo- and hyperthyroidism were significantly higher than normal (P<0.05). In the subclinical hypothyroid (n=7), subclinical hyperthyroid (n=11), and euthyroid Hashimoto's thyroiditis (n=15) groups no correlation was found between thyroid function tests and HDRS, BSI, and HAD scores. Conclusion The results indicate that patients with thyroid disorders have high levels of anxiety and depressive symptoms. Thirty-five patients (43%) out of 80 had an axis I psychiatric disorder. However, our findings did not support an association between high levels of depression and hypothyroidism or between high levels of anxiety and hyperthyroidism. Moreover, this study did not reveal any specific psychiatric manifestation of hypothyroidism or hyperthyroidism.

Thyroid function in clinical subtypes of major depression: an exploratory study

BACKGROUND

Unipolar depression might be characterized by a 'low-thyroid function syndrome'. To our knowledge, this is the first study which explores the possible relationship of DSM-IV depressive subtypes and the medium term outcome, with thyroid function.

MATERIAL

Thirty major depressive patients (DSM-IV) aged 21-60 years and 60 control subjects were included. Clinical Diagnosis: The SCAN v 2.0 and the IPDE were used. The psychometric Assessment included HDRS the HAS and the GAF scales. Free-T3, Free-T4, TSH, Thyroid Binding Inhibitory Immunoglobulins (TBII), Thyroglobulin antibodies (TA) and Thyroid Microsomal Antibodies (TMA) were measured in the serum. The Statistical analysis included 1 and 2-way MANCOVA, discriminant function analysis and Pearson Product Moment Correlation Coefficient.

RESULTS

All depressive subtypes had significantly higher TBII levels in comparison to controls. Atypical patients had significantly higher TMA in comparison to controls. No significant correlation was observed between the HDRS, HAS and GAF scales and thyroid indices. Discriminant function analysis produced functions based on thyroid indices, which could moderately discriminate between diagnostic groups, but could predict good response to treatment with 89.47% chance of success.

CONCLUSION

Although overt thyroid dysfunction is not common in depression, there is evidence suggesting the presence of an autoimmune process affecting the thyroid gland in depressive patients

Subclinical hypothyroidism: a review of neuropsychiatric aspects

The authors review current information about the prevalence, causes, course, and consequences of subclinical hypothyroidism. There is evidence that subclinical hypothyroidism may be associated with cognitive dysfunction, mood disturbance, and diminished response to standard psychiatric treatments. Recommendations are presented for the screening, evaluation and treatment of patients in whom subclinical hypothyroidism may be contributing to neuropsychiatric dysfunction.

Psychoneuroendocrinology of mood disorders. The hypothalamic-pituitary-thyroid axis

Abnormal thyroid functioning can affect mood and influence the course of unipolar and bipolar disorder. Even mild thyroid dysfunction has been associated with changes in mood and cognitive functioning. Thyroid hormone supplementation may have role in the treatment of certain mood disorders, particularly rapid-cycling bipolar disorder. Women are more vulnerable to thyroid dysfunction than men and also respond better to thyroid augmentation. This article reviews the relationship between thyroid function and mood, and the use of thyroid hormones in the treatment of mood disorders. The impact of gender on these issues is also discussed.

Clinical and subclinical hypothyroidism in patients with chronic and treatment-resistant depression

OBJECTIVE

To investigate the relationship between hypothyroidism and treatment-resistant depression (TRD).

METHOD

A retrospective case audit of 93 inpatients of a specialist Mood Disorders Unit. Patients referred with TRD were sub-classified into 'adequate' or 'inadequate' prior treatment groups on the basis of pre-established criteria, and compared with a 'non-TRD' control sample. Grades I (clinical) and II (subclinical) hypothyroidism were determined by review of relevant thyroid indices.

RESULTS

Patients had chronic depressive disorders (sub-group means of 57.5-82.2 weeks of illness). Of those patients referred with TRD, 22% (10/46) had evidence of clinical or subclinical hypothyroidism compared with 2% (1/47) of the non-TRD patients (p < 0.01). A gradient in the rates of grade I hypothyroidism was observed with the adequately-treated TRD patients having the highest rate (13%), the inadequately-treated TRD patients having an intermediate rate (7%), and the non-TRD patients having the lowest rate (2%). Consistent with this view, the inadequately-treated TRD group had the highest rate of grade II hypothyroidism (p = 0.01) and tended to have higher thyroid stimulating hormone (TSH) values (p = 0.06). Differences in the rates of hypothyroidism could not be accounted for by differences in age or prior exposure to lithium and/or carbamazepine. Duration of the depressive episode was negatively correlated with both the free thyroxine indices (r = -0.25, P < 0.05) and TSH levels (r = -0.32, p < 0.01).

CONCLUSIONS

This study suggests that relative hypothyroidism may play a role in the development of some treatment-resistant depressive disorders.

The immune system and major depression

This paper reviews research literature on the links between human immune functioning and mood disorders. It summarizes the initial steps of this fledgling research area since its inception in the late 1970s, and outlines a range of studies that are needed to increase our neuroimmunological sophistication. Future investigations will require greater specificity in several interrelated realms of inquiry: diagnostic, epidemiologic, and physiologic. In particular, this paper highlights basic physiological studies needed in both neurophysiology and immunology to provide a foundation for meaningful examination of their interface. Among the areas that require more specific investigation in both immunologic and mood disorders research is that of temporal organization. Just as psychiatric researchers have begun to scrutinize temporal cycles of mood, behavior, and neurophysiology, so too exploration of immune functioning must take into account predictable temporal cycles such as circadian and ultradian rhythms, as they shape responses to unanticipated external perturbations. Clarification of the temporal dimension will add significantly to our analysis of the links between immune functioning and mood disorders. The basic science of psychoneuroimmunology continues to mature, bringing new discoveries and revealing hitherto unknown mechanisms and interactions. This is a field of study in many ways still on the frontier, and explication of the long suspected links between mood disorders and immune functioning continues to beckon.

Thyrotropin response to TRH stimulation in depressed patients with autoimmune thyroiditis

Two thyroid axis findings are often reported in depressed patients: autoimmune thyroiditis and abnormal thyrotropin (thyroid stimulating hormone, TSH) responses to thyrotropin-releasing hormone (TRH). The TSH response to TRH can be exaggerated, suggesting subclinical hypothyroidism; it can alternatively be blunted, for reasons poorly understood. We selected 28 women who had been found to have major depression for TRH testing. Fifteen patients had autoimmune thyroiditis and 13 had diffuse nontoxic goiter. The endocrinological diagnoses were verified by fine-needle aspiration biopsy and cytological assessment. Patients with overt hypothyroidism and hyperthyroidism were excluded from the study. There were no differences between the two groups in total triiodthyronine and thyroxine plasma levels or severity of depression. In the autoimmune group, basal TSH and Dmax TSH tended to be higher (p < 0.1); peak TSH was significantly higher (p < 0.05), suggesting that the prevalence of subclinical hypothyroidism was also higher. Blunted TSH responses were found about as often in one group as the other.

Effects of thyroid hormones on central nervous system in aging

Support for the many relationships between thyroid hormones and brain function comes from both laboratory and clinical studies. Studies in laboratory animals provide convincing evidence for a neuroregulatory role of thyroid hormones in the brain, suggesting that they may affect behavior. This notion is supported by human studies which have revealed that the effects of thyroid hormones on brain function are most important during the development and maturation of the brain; thereafter, age does not seem to critically affect brain-thyroid hormone relationships.

A perspective on the thyroid and depression

There is extensive literature documenting an association between abnormalities of the hypothalamic-pituitary-thyroid axis and disorders of mood. However, the specific abnormality in thyroid functioning associated with primary affective disorder remains poorly understood. Various aspects of the relationship between thyroid functioning and affective illness are reviewed. Particular attention is paid to psychiatric symptoms and clinical thyroid disorders as well as abnormalities of basal thyroid hormone levels in depression and the use of thyroid hormones in the treatment of depressive illness. Current hypotheses regarding the association between altered thyroid functioning and depressive illness are critically reviewed.

The presence of antithyroid antibodies in patients with affective and nonaffective psychiatric disorders

We determined the frequency of antithyroglobulin and antimicrosomal antibodies in 173 consecutively admitted psychiatric inpatients. (We found antithyroid antibodies in 8% (5/65) of patients with DSM-III major depression, 13% (4/31) with biploar disorder, and in 0% (0/4) of those with schizoaffective disorder.) The rate of antibody occurrence was unrelated to lithium exposure either within individual diagnostic categories or for the sample as a whole. The overall frequency of positive antithyroid antibody titers in patients with DSM-III affective disorder, 9% (9/99), did not differ from that in patients with nonaffective disorders, 10% (7/68). However, patients with bipolar affective disorder-mixed or bipolar affective disorder-depressed had a higher rate of positive antithyroid antibody titers than other patients. Our findings confirm earlier reports that thyroid disorders may be particularly common in patients with bipolar affective disorder, even in the absence of lithium exposure. However, as antithyroid antibodies also occurred at a relatively high rate in nonaffective disorders, the possible psychiatric effects of autoimmune thyroiditis do not appear to be limited to affective dysregulation.