Thyroid function within the normal range and the risk of depression: a population-based cohort study

The Cross-sectional and Longitudinal Association Between Thyroid Function and Depression: A Population-Based Study

CONTEXT

An association of thyroid function with mood disorders has been widely suggested, but very few studies have examined this association longitudinally.

OBJECTIVE

We assessed the cross-sectional and longitudinal association between thyroid function and depression in a population-based cohort.

METHODS

A total of 9471 individuals were included in cross-sectional analyses, of whom 8366 had longitudinal data. At baseline, we assessed thyroid function using serum samples (thyrotropin [TSH], free thyroxine (FT4), and thyroid peroxidase antibodies) and depressive symptoms using the Centre for Epidemiologic Studies Depression (CES-D) scale. Incident depressive events (n = 1366) were continuously followed up with the CES-D and clinical interviews. We analyzed the cross-sectional association of thyroid function and thyroid disease with depressive symptoms using linear and logistic regression, and the longitudinal association with Cox proportional hazard models for depressive events.

RESULTS

Lower TSH levels and lower and higher FT4 levels were cross-sectionally associated with more depressive symptoms with a B value of -0.07 per 1 unit increase of natural log-transformed TSH (95% CI -0.11; -0.04). Furthermore, hypothyroidism was cross-sectionally associated with less depressive symptoms and hyperthyroidism with more depressive symptoms. Longitudinally, there was a U-shaped association between FT4 and incident depressive events but only in euthyroid participants.

CONCLUSION

We show a cross-sectional association between thyroid (dys)function with depressive symptoms, and a U-shaped association between FT4 and incident depressive events in euthyroid individuals. Our findings suggest an association of thyroid function with the risk of developing depression, albeit small. Reverse causation and additional underlying factors may also contribute to the association.

Multi-trait analysis characterizes the genetics of thyroid function and identifies causal associations with clinical implications

To date only a fraction of the genetic footprint of thyroid function has been clarified. We report a genome-wide association study meta-analysis of thyroid function in up to 271,040 individuals of European ancestry, including reference range thyrotropin (TSH), free thyroxine (FT4), free and total triiodothyronine (T3), proxies for metabolism (T3/FT4 ratio) as well as dichotomized high and low TSH levels. We revealed 259 independent significant associations for TSH (61% novel), 85 for FT4 (67% novel), and 62 novel signals for the T3 related traits. The loci explained 14.1%, 6.0%, 9.5% and 1.1% of the total variation in TSH, FT4, total T3 and free T3 concentrations, respectively. Genetic correlations indicate that TSH associated loci reflect the thyroid function determined by free T3, whereas the FT4 associations represent the thyroid hormone metabolism. Polygenic risk score and Mendelian randomization analyses showed the effects of genetically determined variation in thyroid function on various clinical outcomes, including cardiovascular risk factors and diseases, autoimmune diseases, and cancer. In conclusion, our results improve the understanding of thyroid hormone physiology and highlight the pleiotropic effects of thyroid function on various diseases.

The Quartile Levels of Thyroid-Stimulating Hormone by Newborn Screening Stratified Risks of Neurodevelopmental Impairment in Extremely Preterm Infants - A Population Cohort Study

BACKGROUND

To evaluate whether thyroid-stimulating hormone (TSH) by newborn screening (NBS) at birth and at discharge can be surrogate markers for neurodevelopmental impairment (NDI) in extremely preterm infants.

METHODS

The population cohort enrolled infants born <29 weeks' gestation in 2008 - 2020 in southern Taiwan. Infants with a maternal history of thyroid disorders and infants who required thyroxine supplementation during hospitalization were excluded. TSH levels by NBS at birth and at term-equivalent age (TEA)/discharge were respectively categorized into the lowest quartile, the interquartile range, and the highest quartile, which were correlated to NDI outcomes.

RESULTS

Among 392 patients with paired TSH data, 358 (91%) were prospectively followed until corrected age 24 months. At birth, infants with lowest-quartile TSH had higher NDI risks (OR 2.3, 95% CI 1.3 - 4.1, P = 0.004) compared to infants with interquartile-range TSH. Conversely, by TEA/discharge, infants with highest-quartile TSH had increased NDI (OR 1.9, 1.0 - 3.4, P = 0.03). By paired TSH categories, infants persistently in the lowest TSH quartile (48%, aOR 4.4, 1.4 - 14.5, P = 0.01) and those with a shift from interquartile range to the highest quartile (32%, aOR 2.7, 1.0 - 7.4, P = 0.046) had increased NDI risks compared with the reference with consistent interquartile-range TSH.

CONCLUSIONS

Extremely preterm infants persistently in the lowest-quartile TSH level at birth and at discharge had the highest NDI risk. TSH quartile levels by NBS may serve as a population surrogate biomarker for assessing NDI risks in infants born extremely preterm.

Association between thyroid hormone levels in the acute stage of stroke and risk of poststroke depression: A meta-analysis

BACKGROUND

Thyroid hormones have been indicated to be associated with depression, but their relationship with poststroke depression (PSD) remains controversial. Therefore, we performed a meta-analysis to explore the correlation between thyroid hormone levels in acute stroke and PSD.

METHODS

We searched databases for eligible studies. Standard mean differences (SMD) and 95% confidence intervals (CI) were applied to evaluate the association among levels of thyroid hormones, including thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4), in acute stroke patients and the risk of PSD.

RESULTS

A total of 13 studies were included in the analysis. Compared to non-PSD patients, PSD patients had remarkably lower serum TSH and FT3 levels (TSH: SMD = -0.59, 95%CI = -1.04 to -.15, p = .009; FT3: SMD = -0.40, 95%CI = -.51 to -.30, p = .000) and higher serum FT4 levels (SMD = 0.33, 95%CI = .07-.59, p = .013). Subgroup analysis showed that there may be a more statistically significant association between FT3 and the risk of PSD compared to TSH and FT4.

CONCLUSIONS

Our results suggested that patients with lower serum TSH and FT3 levels as well as higher serum FT4 levels in the acute stage of stroke may be more susceptible to PSD.

Thyroid function, renal function, and depression: an association study

Objective

To investigate the correlations between thyroid function, renal function, and depression.

Methods

Clinical data of 67 patients with Major depressive disorder (MDD) and 36 healthy control subjects between 2018 and 2021 were collected to compare thyroid and renal function. Thyroid and renal functions of depressed patients were then correlated with the Hamilton Depression Rating Scale (HAMD) and the Hamilton Anxiety Rating Scale (HAMA).Spearman correlation analysis was used to find the correlation between renal function, thyroid function, and depression. A logistic regression was performed to find significant predictors of depression.

Results

Triiodothyronine protamine (T3), thyroxine (T4), free triiodothyronine protamine (FT3), uric acid, sodium, and anion gap were lower in the MDD group than in the control group (p < 0.05). Correlation analysis of thyroid function, renal function, and factor terms of HAMD in the MDD group suggested that diurnal variation, hopelessness, and depression level were positively correlated with thyrotropin (TSH) (p < 0.05). Cognitive disturbance, retardation, and depression level were negatively correlated with creatinine (p < 0.05). Diurnal variation was negatively correlated with sodium ion (p < 0.01); hopelessness and depression level were positively correlated with chloride ion (p < 0.05); diurnal variation, retardation, and depression level were negatively correlated with anion gap (p < 0.05). Diurnal variation (p < 0.01) and retardation (p < 0.05) were negatively correlated with osmolality. Cognitive disturbance and depression level were positively correlated with estimated glomerular filtration rate (eGFR) (p < 0.05). In the MDD group, correlation analysis of thyroid function, renal function, and HAMA factor terms suggested that the total HAMA score and anxiety level were positively correlated with chloride ion (p < 0.05); psychic anxiety, total HAMA score, and anxiety level were negatively correlated with anion gap (p < 0.05). Furthermore, a low level of anion gap was an independent risk factor for depression and anxiety levels (p < 0.05).

Conclusion

Low thyroid function and reduced waste metabolized by the kidneys in patients with MDD suggest a low intake and low metabolism in depressed patients. In addition, subtle fluctuations in the anion gap in depressed patients were strongly correlated with the degree of depression and anxiety.

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.

Prevalence of overweight and obesity in patients with major depressive disorder with anxiety: Mediating role of thyroid hormones and metabolic parameters

BACKGROUNDS

Anxiety is a common comorbidity in major depressive disorder (MDD); however, its role in overweight and obesity in MDD patients remains unclear. We examined the relationship between severe anxiety and overweight and obesity, as well as the mediating role of thyroid hormones and metabolic parameters in MDD patients.

METHODS

This cross-sectional study recruited 1718 first-episode drug-naïve MDD outpatients. All participants were rated on the Hamilton Depression Rating Scale for depression and Hamilton Anxiety Rating Scale for anxiety and measured in thyroid hormones and metabolic parameters.

RESULTS

A total of 218 (12.7 %) individuals had severe anxiety. The prevalence of overweight and obesity in patients with severe anxiety was 62.8 % and 5.5 %, respectively. Severe anxiety symptoms were related to overweight (Odds Ratio [OR]: 1.47, 95 % CI: 1.08, 2.00) and obesity (OR: 2.10, 95 % CI: 1.07, 4.15). The association between severe anxiety and overweight was mainly attenuated by thyroid hormones (40.4 %), blood pressure (31.9 %), and plasma glucose (19.1 %). For obesity, the association with severe anxiety was mainly attenuated by thyroid hormones (48.2 %), blood pressure (39.1 %), and total cholesterol (28.2 %).

LIMITATIONS

Due to the cross-sectional design, no causal relationship could be derived.

CONCLUSIONS

Thyroid hormones and metabolic parameters can explain the risk of overweight and obesity associated with severe anxiety in MDD patients. These findings add to the knowledge of the pathological pathway of overweight and obesity in severe anxiety comorbid MDD.

Prevalence and risk factors of thyroid dysfunction in outpatients with overweight or obese first-episode and drug-naïve major depressive disorder

BACKGROUND

Thyroid dysfunction is common in patients with major depressive disorder (MDD). However, few studies have examined risk factors for thyroid dysfunction in overweight or obese first-episode and drug-naïve (FEDN) MDD patients. This study aimed to investigate the prevalence and risk factors of thyroid dysfunction in FEDN MDD patients with comorbid high body mass index (BMI).

METHODS

A total of 1718 FEDN MDD patients were included. Hamilton Depression Rating Scale (HAMD), Hamilton Anxiety Rating Scale (HAMA), and Positive and Negative Syndrome Scale (PANSS) positive subscale were used to assess the clinical symptoms of the patients. In addition, metabolic parameters and thyroid hormone levels were measured.

RESULTS

The prevalence of thyroid dysfunction was approximately 1.75 times higher in MDD patients with comorbid overweight or obesity (72.3 %) than in patients without high BMI (58.8 %). The HAMD score, HAMA score, systolic blood pressure (BP), fasting blood glucose (FBG), thyroid peroxidase antibody (TPOAb), total cholesterol (TC), high-density lipoprotein (HDL-C), and low-density lipoprotein (LDL-C), were risk factors for thyroid dysfunction in MDD patients with high BMI. The combination of HAMD, FBG, TC, LDL-C, and systolic BP had a high AUC value of 0.76 differentiating patients with and without thyroid dysfunction.

LIMITATION

Causality cannot be drawn due to cross-sectional design.

CONCLUSIONS

This study demonstrated a high prevalence of thyroid dysfunction in FEDN MDD patients with high BMI. Severity of depression and anxiety, levels of systolic BP, FBG, TPOAb, TC, HDL-C and LDL-C appear to be associated with thyroid dysfunction in FEDN MDD patients with high BMI.

Age-related variation in thyroid function - a narrative review highlighting important implications for research and clinical practice

BACKGROUND

Thyroid hormones are key determinants of health and well-being. Normal thyroid function is defined according to the standard 95% confidence interval of the disease-free population. Such standard laboratory reference intervals are widely applied in research and clinical practice, irrespective of age. However, thyroid hormones vary with age and current reference intervals may not be appropriate across all age groups. In this review, we summarize the recent literature on age-related variation in thyroid function and discuss important implications of such variation for research and clinical practice.

MAIN TEXT

There is now substantial evidence that normal thyroid status changes with age throughout the course of life. Thyroid stimulating hormone (TSH) concentrations are higher at the extremes of life and show a U-shaped longitudinal trend in iodine sufficient Caucasian populations. Free triiodothyronine (FT3) levels fall with age and appear to play a role in pubertal development, during which it shows a strong relationship with fat mass. Furthermore, the aging process exerts differential effects on the health consequences of thyroid hormone variations. Older individuals with declining thyroid function appear to have survival advantages compared to individuals with normal or high-normal thyroid function. In contrast younger or middle-aged individuals with low-normal thyroid function suffer an increased risk of adverse cardiovascular and metabolic outcomes while those with high-normal function have adverse bone outcomes including osteoporosis and fractures.

CONCLUSION

Thyroid hormone reference intervals have differential effects across age groups. Current reference ranges could potentially lead to inappropriate treatment in older individuals but on the other hand could result in missed opportunities for risk factor modification in the younger and middle-aged groups. Further studies are now needed to determine the validity of age-appropriate reference intervals and to understand the impact of thyroid hormone variations in younger individuals.

The use of biochemical indexes in hair for clinical studies of psychiatric diseases: What can we learn about mental disease from hair?

Analysis of hair samples provides unique advantages, including non-invasive sampling, sample stability, and the possibility of additional optimization of high sensitivity detection methods. Hair sample analysis is often used in psychiatric disease research to evaluate previous periods of stress encountered by patients. Glucocorticoid analysis is the most frequently tested indicator of stress. Furthermore, the hypothalamus-pituitary-gonad axis and endocannabinoid system also are involved in the occurrence and development of mental disorders. The endocannabinoid and sex hormone levels in patients experiencing mental illness are considerably different from levels observed in healthy individuals. Nevertheless, due to the different methods used to assess the degree of disease and the range of analytical methods involved in clinical research, the trends in changes for these biomarkers are not uniform. The correlations between changes in biomarker concentrations and illness severity also are not clear. The observed alterations suggest these biochemical substances in hair have potential as biomarkers for diagnosis or predictive treatment. However, the variable results obtained thus far could hamper further development of hair samples for clinical assessment in psychiatric disorders. This article summarizes the published reports documenting the changes in the content of relevant substances in hair in individuals experiencing mental illness and the degree of correlation. In the discussion section, we proposed several issues that should be considered in future studies of hair samples obtained from patients with mental disorders to promote the use of hair sample assessment as an aid in diagnosis or predictive treatment.

Graves' disease as a driver of depression: a mechanistic insight

Graves' disease (GD) is characterized by diffuse enlargement and overactivity of the thyroid gland, which may be accompanied by other physical symptoms. Among them, depression can dramatically damage patients' quality of life, yet its prevalence in GD has not received adequate attention. Some studies have established a strong correlation between GD and increased risk of depression, though the data from current study remains limited. The summary of mechanistic insights regarding GD and depression has underpinned possible pathways by which GD contributes to depression. In this review, we first summarized the clinical evidence that supported the increased prevalence of depression by GD. We then concentrated on the mechanistic findings related to the acceleration of depression in the context of GD, as mounting evidence has indicated that GD promotes the development of depression through various mechanisms, including triggering autoimmune responses, inducing hormonal disorders, and influencing the thyroid-gut-microbiome-brain axis. Finally, we briefly presented potential therapeutic approaches to decreasing the risk of depression among patients with GD.

The prevalence and clinical correlates of suicide attempts in comorbid subclinical hypothyroidism in patients with never-treated major depressive disorder in China

BACKGROUND

Previous studies have emphasized the possible association between subclinical hypothyroidism (SCH) and major depressive disorder (MDD). This study aimed to further investigate suicide attempts and their clinical correlates in MDD patients with comorbid SCH.

METHODS

This cross-sectional study recruited 1706 eligible MDD outpatients. The Hamilton Depression Rating Scale (HAMD), Hamilton Anxiety Rating Scale (HAMA), Positive and Negative Syndrome Scale (PANSS) and Clinical Global Impression of Severity Scale (CGI-S) were applied to evaluate mental status. Fasting blood samples were collected to examine thyroid function. SCH was defined as thyroid stimulating hormone (TSH) > 8 mIU/L with normal free thyroxine levels.

RESULTS

The prevalence of suicide attempts in the SCH group (51.7 %) was significantly higher than that in the non-SCH group (15.4 %; p < 0.001). Logistic regression showed that patients with comorbid SCH were 1.81 times more likely to have attempted suicide as compared with those without (p = 0.001). Among those with TSH > 8 mIU/L, patients with severe anxiety were 3.57 times more likely to attempt suicide compared with those without (p < 0.01). Logistic regression also showed that the CGI-S score (p < 0.001) was independently associated with suicide attempts, while TSH level was not.

CONCLUSIONS

SCH comorbidity may pose a specific hazard in MDD patients due to increased suicide attempts. Exhibiting severe anxiety, overall severity of depressive and psychotic symptoms, but not TSH levels, may be independently correlated with suicide attempts in MDD patients with TSH > 8 mIU/L.

Economic and Cardiometabolic Risk Factors Are Predictors of Lower Thyroid Stimulating Hormone (TSH) Levels in Hispanic/Latinx Adults with Euthyroidism-A Community-Based Study

Thyroid hormone abnormalities are among the most common endocrine disorders comorbidly suffered alongside metabolic syndrome and type 2 diabetes mellitus (T2DM), and within the euthyroid range they may also impact other outcomes, such as mood disorders. This study aimed to observationally examine the relationship between TSH and social determinants of health and clinical measures in a euthyroid Hispanic/Latinx patient sample with a diagnosis of anxiety and/or depression disorders from a community health clinic. A needs assessment was completed using a random sample of 100 de-identified medical records of individuals who received free medical care, including mental health, at a community-based clinic. Those with low normal TSH (<2 mIU/L) compared with high normal TSH (≥2 mIU/L) had a greater odds of food insecurity (p = 0.016) and being at 100% of the federal poverty level (p = 0.015). The low normal TSH group had significantly higher fasting glucose (p = 0.046), hemoglobin A1c (p = 0.018), and total cholesterol (p = 0.034) compared with the high normal TSH group. In those with T2DM, individuals with low normal TSH had six-times greater odds of having high fasting glucose (p = 0.022) and high hemoglobin A1c (p = 0.029). These relationships warrant further study, to inform future public health policies and follow-up care for underserved and vulnerable communities.

The Effects of Common Genetic Variation in 96 Genes Involved in Thyroid Hormone Regulation on TSH and FT4 Concentrations

OBJECTIVE

While most of the variation in thyroid function is determined by genetic factors, single nucleotide polymorphisms (SNPs) identified via genome-wide association analyses have only explained ~5% to 9% of this variance so far. Most SNPs were in or nearby genes with no known role in thyroid hormone (TH) regulation. Therefore, we performed a large-scale candidate gene study investigating the effect of common genetic variation in established TH regulating genes on serum thyrotropin [thyroid-stimulating hormone (TSH)] and thyroxine (FT4) concentrations.

METHODS

SNPs in or within 10 kb of 96 TH regulating genes were included (30 031 TSH SNPs, and 29 962 FT4 SNPs). Associations were studied in 54 288 individuals from the ThyroidOmics Consortium. Linkage disequilibrium-based clumping was used to identify independently associated SNPs. SNP-based explained variances were calculated using SumHer software.

RESULTS

We identified 23 novel TSH-associated SNPs in predominantly hypothalamic-pituitary-thyroid axis genes and 25 novel FT4-associated SNPs in mainly peripheral metabolism and transport genes. Genome-wide SNP variation explained ~21% (SD 1.7) of the total variation in both TSH and FT4 concentrations, whereas SNPs in the 96 TH regulating genes explained 1.9% to 2.6% (SD 0.4).

CONCLUSION

Here we report the largest candidate gene analysis on thyroid function, resulting in a substantial increase in the number of genetic variants determining TSH and FT4 concentrations. Interestingly, these candidate gene SNPs explain only a minor part of the variation in TSH and FT4 concentrations, which substantiates the need for large genetic studies including common and rare variants to unravel novel, yet unknown, pathways in TH regulation.

Relationship of free thyroxine and triiodothyronine on recurrence in maintenance therapy for bipolar depression

OBJECTIVE

To examine whether thyroid function in the normal range is associated with recurrence of depressive or mania in bipolar disorder patients.

METHODS

104 patients with bipolar disorder in maintenance therapy phase were assigned randomly to mood stabilizer combined with antidepressant group or mood stabilizer group. There were 52 patients in both groups respectively. Clinical symptoms were assessed at baseline, 3rd month, 6th month, 9th month, and 12th month using HAMD-17 and YMRS. Blood samples were analyzed for thyroid function.

RESULTS

There was no statistically significant difference of recurrence rate of depressive episode and mania episode at the end of the 12-months between mood stabilizer combined with antidepressant group and mood stabilizer group. There was significant relation of baseline TT4 (P = 0.020, HR = 0.948), FT3 (P = 0.035, HR = 2.055), and FT4 (P = 0.047, OR=0.769) with the recurrence of depressive episode in mood stabilizer group. The area under curve (AUC) of TT4, FT3, FT4 were 0.685, 0.613, 0.544, respectively. There was significant relation of baseline FT3 (P = 0.044，HR = 4.493) with the recurrence of mania episode for mood stabilizer combined with antidepressants group. The AUC of FT3 was 0.806.

CONCLUSION

Low level of TT4, FT4 and high level of FT3 within normal-range were related with the recurrence of depressive episode in the maintenance treatment with mood stabilizer of bipolar disorder. High level of FT3 within normal-range were related with recurrence of mania when mood stabilizer combined with antidepressants were used in the maintenance treatment of bipolar disorder.

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.

Redefining the Cut-Off Ranges for TSH Based on the Clinical Picture, Results of Neuroimaging and Laboratory Tests in Unsupervised Cluster Analysis as Individualized Diagnosis of Early Schizophrenia

Thyroid abnormalities, including mild forms of hypothyroidism and hyperthyroidism, are reported as risk factors for the development of a number of neuropsychiatric disorders, including schizophrenia. The diagnostic process still takes into account the extreme ranges of the accepted reference values for serum TSH since the concentration of free thyroxine in the serum does not change by definition. TSH mU/L cut-off values in psychiatric patients are currently clinically considered in the case of extremely high serum TSH levels (>4.0 mU/L). The results obtained in this study suggest that the clinically significant value has a lower TSH cut-off point with an upper limit of 2–2.5 mU/L. The criteria for the differential diagnosis of patients with schizophrenia, however, mainly take into account statutory reference ranges without a background related to the history of thyroid diseases in the family. The results indicate the need to lower the upper cut-off values for TSH among patients with early psychosis, which is related to the potential clinical significance of the obtained values both in the field of clinical evaluation and neuroimaging and laboratory evaluation parameters. The cut-off points obtained with the prior available knowledge coincided with the values established in the unsupervised clustering method, which further confirms the legitimacy of their use in the individualized diagnosis strategy of schizophrenia.

Relationship between thyroid hormone and sex hormone levels and non-suicidal self-injury in male adolescents with depression

OBJECTIVE

Non-suicidal self-injury (NSSI) is the intentional and repeated direct injury to one's bodily tissues or organs without the intent to die, which is not socially sanctioned and does not result in death. This study will be the first to explore the relationship between NSSI behavior and thyroid hormone and sex hormone levels in male adolescents with depression.

METHODS

Among the inpatients in the children's ward of Shandong Mental Health Center, eighty male patients with first-episode depressive disorder were randomly selected. Forty male adolescent depressed patients with NSSI behaviors were set as the NSSI group, and forty male adolescent depressed patients without NSSI behaviors were set as the No-NSSI group. Their thyroid hormones (free triiodothyronine, free thyroxine, and thyroid stimulating hormone) and sex hormones (estradiol, progesterone, and testosterone) were measured, and the severity of self-injury in the NSSI group was assessed using the Adolescent Self-Injury Questionnaire. The NSSI group was tested again after 6 weeks of sertraline treatment for biological indicators and assessed by the Self-Injury Questionnaire to compare the hormonal differences between the NSSI group and the No-NSSI group and compare the differences of each index before and after treatment in the NSSI group.

RESULTS

T3/T4 (p = 0.001) and FT3 (p = 0.023), TSH levels (p < 0.001) were lower in the NSSI group than in the No-NSSI group before treatment, and FT4 (p = 0.036) and T (p < 0.001) levels were higher than in the No-NSSI group. T3/T4 levels were higher in the NSSI group after treatment (p < 0.001). FT4 (p < 0.001) and T (p = 0.001) levels and self-injury questionnaire scores (p < 0.001) decreased after treatment in the NSSI group. In the NSSI group at baseline, FT4 levels were negatively correlated with self-injury questionnaire scores (r = -0.459, p = 0.003) and testosterone levels were positively correlated with self-injury questionnaire scores (r = 0.383, p = 0.015), and in the NSSI group after treatment, FT4 difference was negatively correlated with self-injury questionnaire score reduction rate (r = -0.037, p = 0.019), and testosterone difference was positively correlated with self-injury questionnaire score reduction rate (r = 0.424, p = 0.006). Logistic regression analysis showed that low TSH and high testosterone levels were independent risk factors for the development of non-suicidal self-harming behaviors in male adolescent depressed patients.

CONCLUSION

Changes in thyroid hormone and sex hormone levels may be associated with non-suicidal self-injurious behavior in male adolescent depressed patients.

Association of Hypothyroidism and Clinical Depression: A Systematic Review and Meta-analysis

IMPORTANCE

Hypothyroidism is considered a cause of or a strong risk factor for depression, but recent studies provide conflicting evidence regarding the existence and the extent of the association. It is also unclear whether the link is largely due to subsyndromal depression or holds true for clinical depression.

OBJECTIVE

To estimate the association of hypothyroidism and clinical depression in the general population.

DATA SOURCES

PubMed, PsycINFO, and Embase databases were searched from inception until May 2020 for studies on the association of hypothyroidism and clinical depression.

STUDY SELECTION

Two reviewers independently selected epidemiologic and population-based studies that provided laboratory or International Statistical Classification of Diseases and Related Health Problems diagnoses of hypothyroidism and diagnoses of depression according to operationalized criteria (eg, Diagnostic and Statistical Manual of Mental Disorders or International Statistical Classification of Diseases and Related Health Problems) or cutoffs in established rating scales.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently extracted data and evaluated studies based on the Newcastle-Ottawa Scale. Summary odds ratios (OR) were calculated in random-effects meta-analyses.

MAIN OUTCOMES AND MEASURES

Prespecified coprimary outcomes were the association of clinical depression with either hypothyroidism or autoimmunity.

RESULTS

Of 4350 articles screened, 25 studies were selected for meta-analysis, including 348 014 participants. Hypothyroidism and clinical depression were associated (OR, 1.30 [95% CI, 1.08-1.57]), while the OR for autoimmunity was inconclusive (1.24 [95% CI, 0.89-1.74]). Subgroup analyses revealed a stronger association with overt than with subclinical hypothyroidism, with ORs of 1.77 (95% CI, 1.13-2.77) and 1.13 (95% CI, 1.01-1.28), respectively. Sensitivity analyses resulted in more conservative estimates. In a post hoc analysis, the association was confirmed in female individuals (OR, 1.48 [95% CI, 1.18-1.85]) but not in male individuals (OR, 0.71 [95% CI, 0.40-1.25]).

CONCLUSIONS AND RELEVANCE

In this systematic review and meta-analysis, the effect size for the association between hypothyroidism and clinical depression was considerably lower than previously assumed, and the modest association was possibly restricted to overt hypothyroidism and female individuals. Autoimmunity alone may not be the driving factor in this comorbidity.

Homeostatic and endocrine responses as the basis for systemic therapy with medical gases: ozone, xenon and molecular hydrogen

Among medical gases, including gases used therapeutically, this review discusses the comparative physiological activity of three gases - ozone (O3), xenon (Xe) and molecular hydrogen (H2), which together form representatives of three types of substances - typical oxidizing, inert, and typical reducing agents. Upon analysis of published and proprietary data, we concluded that these three medical gases can manipulate the neuroendocrine system, by modulating the production or release of hormones via the hypothalamic-pituitary-adrenal, hypothalamic-pituitary-thyroid, hypothalamic-pituitary-gonadal axes, or the gastrointestinal pathway. With repeated administration of the gases over time, these modulations become a predictable consequence of conditioned homeostatic reflexes, resulting in regulation of physiological activity. For example, the regular activation of the unconditioned defense reflex in response to repeated intoxication by ozone leads to the formation of an anticipatory stable conditioned response, which counteracts the toxic action of O3. The concept of a Pavlovian conditioned reflex (or hormoligosis) is a brief metaphor for the understanding the therapeutic effect of systemic ozone therapy.

Effects of Chronic Suppression or Oversuppression of Thyroid-Stimulating Hormone on Psychological Symptoms and Sleep Quality in Patients with Differentiated Thyroid Cancer

In differentiated thyroid cancer (DTC), the standard treatment includes total thyroidectomy and lifetime levothyroxine (LT4) replacement. However, long-term exogenous LT4 has become controversial due to the adverse effects of oversuppression. The study included 191 patients (aged 18-76 years) with a prospective diagnosis of non-metastatic DTC and 79 healthy individuals. The patients with DTC were stratified into three groups according to their TSH levels: suppressed thyrotropin if TSH was below 0.1 μIU/ml, mildly suppressed thyrotropin if TSH was between 0.11 and 0.49 μIU/ml, and low-normal thyrotropin if THS was between 0.5 and 2 μIU/ml. The Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), Anxiety Sensitivity Index (ASI), Short Symptom Inventory (SSI), and Pittsburgh Sleep Quality Index (PSQI) were administered to all participants. It was found that the BDI, BAI, SSI and PSQI scores were worse in patients with DTC (p=0.024, p=0.014, p=0.012, and p=0.001, respectively). According to theTSH levels, the mean ASI was found to be higher in the suppressed and mildly suppressed thyrotropin groups (19±14.4 vs. 10.6±11.1; 16.4±14.9 vs. 10.6±11.1, p=0.024, respectively), the mean SSI was found higher in the suppressed group (61.0±55.5 vs. 35.1±37.0, p=0.046), and the mean PSQI was higher in all three groups (7.94±3.97 vs. 5.35±4.13; 7.21±4.59 vs. 5.35±4.13; 7.13±4.62 vs. 5.35±4.13, p=0.006) when compared with the controls. No significant difference was found between the groups. A positive correlation was detected in the duration of LT4 use and BDI and SSI, and a weak, negative correlation was detected between TSH levels and ASI and PSQI. Based on our study, it was found that depression, anxiety disorders, and sleep problems were more prevalent in patients with DTC, being more prominent in the suppressed TSH group. These results were inversely correlated with TSH values and positively correlated with the duration of LT4 use. Unnecessary LT4 oversuppression should be avoided in patients with DTC.

Associations of Thyroid Hormones Profile During Normal Pregnancy and Postpartum With Anxiety, Depression, and Obsessive/Compulsive Disorder Scores in Euthyroid Women

Objective

Thyroid dysfunction (overt and subclinical) has been consistently linked to pregnancy adversity and abnormal fetal growth and development. Mood disorders such as anxiety, depression, and obsessive-compulsive disorder (OCD) are frequently diagnosed during pregnancy and at postpartum, and emerging evidence suggests association with impaired offspring neurodevelopment and growth. This study aimed to examine potential associations between thyroid function and mood symptoms during pregnancy and postpartum.

Design

This is a prospective study measuring thyroid hormones and assessing mood symptoms by employing specific questionnaires in the same cohort of 93 healthy pregnant women at the 24th (2nd trimester) and 36th (3rd trimester) gestational weeks and at the 1st postpartum week.

Methods

Serum thyroid hormones, TSH, anti-TPO, and anti-Tg antibodies were measured at the 24th (2nd trimester) and 36th (3rd trimester) gestational weeks and at the 1st postpartum week. Specific validated questionnaires were employed at the same time-points to assess separately symptoms of anxiety [Generalized Anxiety Disorder Inventory (GADI), Penn State Worry Questionnaire (PSWQ), STAI-State Anxiety inventory (STAI-S), STAI-Trait Anxiety Inventory (STAI-T)], depression [Edinburgh Postnatal Depression Scale (EPDS), Stein’s Blues Scale (BLUES), Beck Depression Inventory (BDI)], and obsessive compulsive disorder (OCD) [Yale-Brown Obsessive Compulsive scale (Y-BOCS)].

Results

At the 2nd trimester, GADI score correlated negatively with FT3 (p < 0.010, r = −0.545) and positively with TSH (p < 0.050, r = 0.837) concentrations; GADI, PSWQ, EPDS and Y-BOCS scores correlated negatively with FT4 concentrations (p < 0.010, r = −0.768; p < 0.010, r = −0.384; p < 0.050, r = −0.364; p < 0.010, r = −0.544, respectively). At the 3rd trimester, BLUES score correlated positively with rT3 concentrations (p = 0.00, r = 0.89); GADI, EPDS, and Y-BOCS scores correlated negatively with FT4 concentrations (p = 0.001, r = − 0.468; p = 0.036, r = −0.39; p = 0.001, r = −0.625, respectively); GADI, STAI-S, and Y-BOCS scores correlated positively with TSH concentrations (p = 0.015, r = 0.435; p = 0.024, r = 0.409 p = 0.041, r = 0.389, respectively). At postpartum, PSWQ, STAI-T, EPDS, and BDI scores correlated positively with rT3 concentrations (p = 0.024, r = 0.478; p = 0.014, r = 0.527; p = 0.046, r = 0.44; p = 0.021, r = 0.556, respectively, Y-BOCS score correlated positively with TSH (p = 0.045, r = 0.43), and BLUES score correlated positively with anti-TPO antibody concentrations (p = 0.070, r = 0.586).

Conclusion

The reported findings demonstrate positive associations between low-normal thyroid function at the 2nd and 3rd trimesters of pregnancy and postpartum with anxiety, depression, and OCD scores.

Thyroid Function and Mood Disorders: A Mendelian Randomization Study

Background: Observational studies suggest that even minor variations in thyroid function are associated with the risk of mood disorders, including major depressive disorder (MDD) and bipolar disorder (BD). However, it is unknown whether these associations are causal or not. We used a Mendelian randomization (MR) approach to investigate causal effects of minor variations in thyrotropin (TSH) and free thyroxine (fT4) levels on MDD and BD risk. Materials and Methods: We performed two-sample MR analyses using data from the largest publicly available genome-wide association studies on normal-range TSH (n = 54,288) and fT4 (n = 49,269) levels, MDD (170,756 cases, 329,443 controls) and BD (20,352 cases, 31,358 controls). Secondary MR analyses investigated the effects of TSH and fT4 levels on specific MDD and BD subtypes. Reverse MR was also performed to assess the effects of MDD and BD on TSH and fT4 levels. Results: There were no associations between genetically predicted TSH and fT4 levels and MDD risk, nor MDD subtypes and minor depressive symptoms. A one standard deviation increase in fT4 levels was nominally associated with an 11% decrease in the overall BD risk (odds ratio [OR] = 0.89, 95% confidence interval [CI] = 0.80-0.98, p = 0.022) and a 13% decrease in the BD type 1 risk (OR = 0.87, CI = 0.75-1.00, p = 0.047). In the reverse direction, genetic predisposition to MDD and BD was not associated with TSH nor fT4 levels. Conclusions: Variations in normal-range TSH and fT4 levels have no effects on the risk of MDD and its subtypes, and neither on minor depressive symptoms. This indicates that depressive symptoms should not be attributed to minor variations in thyroid function. Borderline associations with BD and BD type 1 risks suggest that further clinical studies should investigate the effect of thyroid hormone treatment in BD.

Epigenome-Wide Association Study of Thyroid Function Traits Identifies Novel Associations of fT3 With KLF9 and DOT1L

CONTEXT

Circulating concentrations of free triiodothyronine (fT3), free thyroxine (fT4), and thyrotropin (TSH) are partly heritable traits. Recent studies have advanced knowledge of their genetic architecture. Epigenetic modifications, such as DNA methylation (DNAm), may be important in pituitary-thyroid axis regulation and action, but data are limited.

OBJECTIVE

To identify novel associations between fT3, fT4, and TSH and differentially methylated positions (DMPs) in the genome in subjects from 2 Australian cohorts.

METHOD

We performed an epigenome-wide association study (EWAS) of thyroid function parameters and DNAm using participants from: Brisbane Systems Genetics Study (median age 14.2 years, n = 563) and the Raine Study (median age 17.0 years, n = 863). Plasma fT3, fT4, and TSH were measured by immunoassay. DNAm levels in blood were assessed using Illumina HumanMethylation450 BeadChip arrays. Analyses employed generalized linear mixed models to test association between DNAm and thyroid function parameters. Data from the 2 cohorts were meta-analyzed.

RESULTS

We identified 2 DMPs with epigenome-wide significant (P < 2.4E-7) associations with TSH and 6 with fT3, including cg00049440 in KLF9 (P = 2.88E-10) and cg04173586 in DOT1L (P = 2.09E-16), both genes known to be induced by fT3. All DMPs had a positive association between DNAm and TSH and a negative association between DNAm and fT3. There were no DMPs significantly associated with fT4. We identified 23 differentially methylated regions associated with fT3, fT4, or TSH.

CONCLUSIONS

This study has demonstrated associations between blood-based DNAm and both fT3 and TSH. This may provide insight into mechanisms underlying thyroid hormone action and/or pituitary-thyroid axis function.

Nerve impulse transmission pathway-focused genes expression analysis in patients with primary hypothyroidism and autoimmune thyroiditis

OBJECTIVE

Thyroid hormones have important actions in the adult brain. They regulate genes expression in myelination, differentiation of neuronal and glial cells, and neuronal viability and function.

METHODS

We used the pathway-specific real-time PCR array (Neurotrophins and Receptors RT2 Profiler PCR Array, QIAGEN, Germany) to identify and verify nerve impulse transmission pathway-focused genes expression in peripheral white blood cells of patients with postoperative hypothyroidism, hypothyroidism as a result of autoimmune thyroiditis (AIT) and AIT with elevated serum an anti-thyroglobulin (anti-Tg) and anti-thyroid peroxidase (anti-TPO) antibodies.

RESULTS

It was shown that patients with postoperative hypothyroidism and hypothyroidism resulting from AIT had significantly lower expression of BDNF and CBLN1. In patients with AIT with elevated serum anti-Tg and anti-TPO antibodies, the expression of GDNF was significantly down-regulated and the expression of PNOC was up-regulated. The expression levels of MEF2C and NTSR1 were decreased in the group of patients with postoperative hypothyroidism and AIT, correspondingly.

CONCLUSIONS

The results of this study demonstrate that AIT and hypothyroidism can affect the expression of mRNA nerve impulse transmission genes in gene specific manner and that these changes in gene expressions can be playing a role in the development of neurological complications associated with thyroid pathology. Detection of the transcriptional activity of nerve impulse transmission genes in peripheral white blood cells can be used as an important minimally invasive prognostic marker of the risk for developing neurological complications comorbid with thyroid pathology.

Outcomes of Thyroid Dysfunction in People Aged Eighty Years and Older: An Individual Patient Data Meta-Analysis of Four Prospective Studies (Towards Understanding Longitudinal International Older People Studies Consortium)

Background: Subclinical and overt thyroid dysfunction is easily detectable, often modifiable, and, in younger age groups, has been associated with clinically relevant outcomes. Robust associations in very old persons, however, are currently lacking. This study aimed to investigate the associations between (sub-)clinical thyroid dysfunction and disability in daily living, cognitive function, depressive symptoms, physical function, and mortality in people aged 80 years and older. Methods: Four prospective cohorts participating in the Towards Understanding Longitudinal International older People Studies (TULIPS) consortium were included. We performed a two-step individual participant data meta-analysis on source data from community-dwelling participants aged 80 years and older from the Netherlands, New Zealand, United Kingdom, and Japan. Outcome measures included disability in daily living (disability in activities of daily living [ADL] questionnaires), cognitive function (Mini-Mental State Examination [MMSE]), depressive symptoms (Geriatric Depression Scale [GDS]), physical function (grip strength) at baseline and after 5 years of follow-up, and all-cause five-year mortality. Results: Of the total 2116 participants at baseline (mean age 87 years, range 80-109 years), 105 participants (5.0%) were overtly hypothyroid, 136 (6.4%) subclinically hypothyroid, 1811 (85.6%) euthyroid, 60 (2.8%) subclinically hyperthyroid, and 4 (0.2%) overtly hyperthyroid. Participants with thyroid dysfunction at baseline had nonsignificantly different ADL scores compared with euthyroid participants at baseline and had similar MMSE scores, GDS scores, and grip strength. There was no difference in the change of any of these functional measures in participants with thyroid dysfunction during five years of follow-up. Compared with the euthyroid participants, no 5-year survival differences were identified in participants with overt hypothyroidism (hazard ratio [HR] 1.0, 95% confidence interval [CI 0.6-1.6]), subclinical hypothyroidism (HR 0.9 [CI 0.7-1.2]), subclinical hyperthyroidism (HR 1.1 [CI 0.8-1.7]), and overt hyperthyroidism (HR 1.5 [CI 0.4-5.9]). Results did not differ after excluding participants using thyroid-influencing medication. Conclusions: In community-dwelling people aged 80 years and older, (sub-)clinical thyroid dysfunction was not associated with functional outcomes or mortality and may therefore be of limited clinical significance.

Heterogeneity and Dynamics of Vasculature in the Endocrine System During Aging and Disease

The endocrine system consists of several highly vascularized glands that produce and secrete hormones to maintain body homeostasis and regulate a range of bodily functions and processes, including growth, metabolism and development. The dense and highly vascularized capillary network functions as the main transport system for hormones and regulatory factors to enable efficient endocrine function. The specialized capillary types provide the microenvironments to support stem and progenitor cells, by regulating their survival, maintenance and differentiation. Moreover, the vasculature interacts with endocrine cells supporting their endocrine function. However, the structure and niche function of vasculature in endocrine tissues remain poorly understood. Aging and endocrine disorders are associated with vascular perturbations. Understanding the cellular and molecular cues driving the disease, and age-related vascular perturbations hold potential to manage or even treat endocrine disorders and comorbidities associated with aging. This review aims to describe the structure and niche functions of the vasculature in various endocrine glands and define the vascular changes in aging and endocrine disorders.

Prevalence of Thyroid Dysfunction Among Depression Patients in a Tertiary Care Centre

Introduction:

Patients with thyroid disorders are more prone to develop depressive symptoms and conversely depression may be accompanied by various subtle thyroid abnormalities. The aim of the study was to estimate the prevalence of thyroid dysfunction in depression.

Methods:

This is a descriptive cross-sectional study conducted at Devdaha Medical College and Research Institute employing a simple random sampling technique during the period of August 2019-January 2020. The research was approved by the Ethical Committee of the Institutional Review Board of Devdaha Medical College and Research Institute. The protocol approval number is 009/019. Data analysis was done in Statistical Package for the Social Sciences (Version 23). Results were presented as frequencies and percentages where required.

Results:

Among 263 patients with depression, 69 (26.2%) had abnormal thyroid status with most common being subclinical hypothyroidism 32 (12.2%), 13 (4.9%) overt hypothyroidism and 7 (2.7%) overt hyperthyroidism.

Conclusions:

The prevalence of thyroid dysfunction is high among patients with depression. We recommend to conduct routine thyroid function tests for all the patients with depression.

Evaluation of anxiety and depression in patients with thyroid function disorder

OBJECTIVES We aim to determine the anxiety and depression levels of patients treated for hypothyroidism who assumed euthyroid status. These patients also frequently attend family medicine outpatient clinics. METHODS This study was conducted on 76 euthyroid volunteer participants (patient groups) who were treated for hypothyroidism and followed-up and 22 healthy volunteers (control group). Questionnaires were administered to all participants to assess anxiety and depression levels. The Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI) were applied to all the groups. In addition, BAI sub-parameters were evaluated in detail. RESULTS At least mild depression was detected in 54.5% of the first group, 41.7% of the second group, and 33.3% of the third group. When the BDI and BAI total scores of the participants in different groups were compared, statistically significant differences were determined. Statistically significant results were detected related to different BAI sub-parameters between the patient groups and in comparison to the fourth group. CONCLUSIONS We found that patients were predisposed to anxiety and depression even if they were euthyroid. When the sub-parameters of BAI were evaluated in detail, we observed that the duration of the disease significantly affected some anxiety-related symptoms.

Effect of increased levothyroxine dose on depressive mood in older adults undergoing thyroid hormone replacement therapy

OBJECTIVE

Depressive mood consequent to hypothyroidism can be reversed with levothyroxine (LT4) replacement therapy. However, it is unclear whether increasing LT4 dose confers additional mood benefits.

DESIGN AND PATIENTS

A single-blinded before-and-after study of 24 patients with hypothyroidism who were aged 65 years or older and undergoing LT4 replacement therapy with stable doses.

MEASUREMENTS

Geriatric Depression Scale (GDS-K) and Hyperthyroid Symptom Scale (HSS-K) were assessed at baseline, 3 months after increasing LT4 dose by an additional 12.5 µg/d, and finally 3 months after returning to the baseline dose.

RESULTS

Serum thyroid-stimulating hormone (TSH) concentrations decreased at the higher LT4 dose (1.95 ± 2.16 vs 0.47 ± 1.09 mIU/L, P < .001) and recovered after returning to the baseline dose. Serum-free thyroxine levels and HSS-K scores were unchanged during the study period. GDS-K scores improved on the increased dose (9.5 ± 6.6 vs 7.5 ± 4.7, P = .029), and this improvement was maintained after returning to the baseline dose (9.5 ± 6.6 vs 7.4 ± 5.4, P = .010). Higher serum TSH was independently associated with both higher GDS-K and depression risk among those with depressive mood (GDS-K > 10) at baseline.

CONCLUSIONS

Depressive mood improves with increased LT4 dose, without significant hyperthyroid symptoms or signs, in older adults undergoing thyroid hormone replacement. These findings suggest the potential for varying the treatment target for hypothyroidism based on mood status and that low-dose LT4 treatment might be an ancillary treatment for depression.

The effect of iatrogenic subclinical hyperthyroidism on anxiety, depression and quality of life in differentiated thyroid carcinoma

Background/aim

Overt thyroidism is known to cause neuropsychiatric disorders but studies on subclinical hyperthyroidism (SCH) are limited. Subclinical hyperthyroidism induction by administering L-Thyroxine (LT4) is the standard treatment method in differentiated thyroid carcinoma (DTC) follow-up. Our aim was to investigate whether anxiety, depression and quality of life are affected in DTC patients followed-up with exogenous SCH.

Materials and methods

The patients were divided into exogenous SCH by LT4-DTC (n = 127), euthyroid-DTC (n = 66) and exogenous euthyroid-benign thyroid noduüle (BTN) who underwent thyroidectomy for benign thyroid pathology (n = 85) groups.

Results

The rate of moderate/severe anxiety was significantly higher in SCH-DTC than euthyroid-BTN group (27.5%, n = 35 vs. 9.4%, n = 8) (P = 0.001). TSH levels and Beck anxiety inventory (BAI) scores were significantly negatively correlated(P = 0.009 r = –0.16). Free T4 and BAI were significantly positively correlated (P = 0.04 r = 0.4). The groups were similar in terms of depression severity (P = 0.15). Subclinical hyperthyroid-DTC group scored significantly lowerthan euthyroid-BTN group in all scales of SF-36 quality of life survey.

Conclusion

LT4-induced SCH, which is a part of traditional DTC treatment, can exacerbate the anxiety symptoms in patients and disrupt their quality of life, depending on the level of fT4.

The Genetic Basis of Thyroid Function: Novel Findings and New Approaches

CONTEXT

Genetic factors are major determinants of thyroid function. Over the last two decades, multiple genetic variants have been associated with variations in normal range thyroid function tests. Most recently, a large-scale genome-wide association study (GWAS) doubled the number of known variants associated with normal range thyrotropin (TSH) and free thyroxine (FT4) levels.

EVIDENCE ACQUISITION

This review summarizes the results of genetic association studies on normal range thyroid function and explores how these genetic variants can be used in future studies to improve our understanding of thyroid hormone regulation and disease.

EVIDENCE SYNTHESIS

Serum TSH and FT4 levels are determined by multiple genetic variants on virtually all levels of the hypothalamus-pituitary-thyroid (HPT) axis. Functional follow-up studies on top of GWAS hits has the potential to discover new key players in thyroid hormone regulation, as exemplified by the identification of the thyroid hormone transporter SLC17A4 and the metabolizing enzyme AADAT. Translational studies may use these genetic variants to investigate causal associations between thyroid function and various outcomes in Mendelian Randomization (MR) studies, to identify individuals with an increased risk of thyroid dysfunction, and to predict the individual HPT axis setpoint.

CONCLUSIONS

Recent genetic studies have greatly improved our understanding of the genetic basis of thyroid function, and have revealed novel pathways involved in its regulation. In addition, these findings have paved the way for various lines of research that can improve our understanding of thyroid hormone regulation and thyroid diseases, as well as the potential use of these markers in future clinical practice.

Anger and Depression in Middle-Aged Men: Implications for a Clinical Diagnosis of Chronic Traumatic Encephalopathy

OBJECTIVE

In recent years, it has been proposed that problems with anger control and depression define clinical features of chronic traumatic encephalopathy (CTE). The authors examined anger problems and depression in middle-aged men from the general population and related those findings to the proposed clinical criteria for CTE.

METHODS

A sample of 166 community-dwelling men ages 40-60 was extracted from the normative database of the National Institutes of Health Toolbox. All participants denied prior head injury or traumatic brain injury (TBI). Participants completed scales assessing anger, hostility, aggression, anxiety, and depression.

RESULTS

In response to the item "I felt angry," 21.1% of men reported "sometimes," and 4.8% reported "often." When asked "If I am provoked enough I may hit another person," 11.4% endorsed the statement as true. There were moderate correlations between anger and anxiety (Spearman's ρ=0.61) and between depression and affective anger (ρ=0.51), hostility (ρ=0.56), and perceived hostility (ρ=0.35). Participants were dichotomized into a possible depression group (N=49) and a no-depression group (N=117) on the basis of the question "I feel depressed," specific to the past 7 days. The possible depression group reported higher anxiety (p<0.001, Cohen's d=1.51), anger (p<0.001, Cohen's d=0.96), and hostility (p<0.001, Cohen's d=0.95).

CONCLUSIONS

Some degree of anger and aggression are reported by a sizable minority of middle-aged men in the general population with no known history of TBI. Anger and hostility are correlated with depression and anxiety, indicating that all tend to co-occur. The base rates and comorbidity of affective dysregulation in men in the general population is important to consider when conceptualizing CTE phenotypes.

Prevalence and clinical correlates of subclinical hypothyroidism in first-episode drug-naive patients with major depressive disorder in a large sample of Chinese

BACKGROUND

The coexistence of subclinical hypothyroidism (SCH) and depression has been intensively examined in the patients receiving thyroxine or antidepressant treatment. This study aimed to investigate the prevalence and clinical correlates of severe SCH in Chinese first-episode drug naïve patients with major depressive disorder (MDD).

METHODS

Using a cross-sectional design, we recruited a total of 1706 MDD patients. Depressive symptoms were evaluated using the 17-item Hamilton Depression Rating Scale (HAMD). Severity of anxiety and psychiatric symptoms were evaluated by the Hamilton Anxiety Rating Scale (HAMA) and the Positive and Negative Syndrome Scale (PANSS), respectively. Serum thyroid function parameters were measured by a chemiluminescence immunoassay. Based on the serum thyroid stimulating hormone (TSH) level, SCH was further divided into mild (TSH < 10 mIU/L) and severe SCH (TSH ≥ 10 mIU/L).

RESULTS

More patients with severe SCH had severe anxiety, psychotic symptoms, suicide attempts (all p < 0.001), compared with those without severe SCH. Logistic regression showed that suicide attempts and psychiatric symptoms were associated with severe SCH (both p < 0.001). Multiple linear regression showed that age (p < 0.05), BMI (p < 0.001), HAMD score (p < 0.001), HAMA score (p < 0.001), PANSS positive subscore (p = 0.001) and CGI score (p = 0.001) were associated with TSH levels.

CONCLUSION

Our findings suggest that suicide attempts and psychiatric symptoms may be associated with severe SCH. Moreover, severe anxiety, depressive and psychotic symptoms, as well as older age and higher BMI are possibly related to elevated TSH levels.

Adult onset of type 3 deiodinase deficiency in mice alters brain gene expression and increases locomotor activity

Constitutive loss of the type 3 deiodinase (DIO3) causes abnormally increased levels of thyroid hormone action in the developing and adult brain, leading to an array of behavioral abnormalities. To determine to what extent those phenotypes derive from a lack of DIO3 in the adult brain, versus developmental consequences, we created a mouse model of conditional DIO3 inactivation. Mice carrying "floxed" Dio3 alleles and a tamoxifen-inducible cre transgene were injected with tamoxifen at two months of age. Compared to oil-injected controls, the brain tissue of these mice showed a 75-80% decrease in DIO3 activity and 85-95% Dio3 mRNA was expressed from recombinant alleles. Mice with adult DIO3 deficiency did not show significant differences in growth, serum thyroid hormone parameters or behaviors related to anxiety and depression. However, female mice exhibited elevated locomotor activity and increased marble-burying behavior. They also manifested relatively modest alterations in the expression of T3-dependent genes and genes related to hyperactivity in a sex- and region-specific manner. Upon thyroid hormone treatment, the expression response of T3-regulated genes was generally more pronounced in DIO3-deficient female mice than in female controls, while the opposite effect of altered genotype was noticed in males. The extent of the molecular and behavioral phenotypes of adult-onset DIO3 deficiency suggests that a substantial proportion of the neurological abnormalities caused by constitutive DIO3 deficiency has a developmental origin. However, our results show that DIO3 in the adult brain also influences behavior and sensitivity to thyroid hormone action in a sexually dimorphic fashion.

Mood Disorders in Levothyroxine-Treated Hypothyroid Women

Background: Hypothyroidism has several symptoms (weight gain, arrhythmias, mood changes, etc.). The aims of this study were (1) to assess the prevalence of anxiety and depression in levothyroxine-treated hypothyroid women and in women without hypothyroidism; (2) to identify variables associated with anxiety and depression. Methods: A case-control study was performed with 393 women. Case-group: 153 levothyroxine-treated hypothyroid women. Control-group: 240 women without hypothyroidism. Convenience sampling. Instrument: The Hamilton Hospital Anxiety and Depression Scale (HADS), and a sociodemographic questionnaire. Results: The prevalence of anxiety in levothyroxine-treated hypothyroid women was higher than in women without hypothyroidism (29.4% vs. 16.7%, χ² p < 0.001). The prevalence of depression in the case group was higher than in the control group (13.1% vs. 4.6%, χ² p < 0.001). Levothyroxine-treated hypothyroid women were more likely to have anxiety (OR = 2.08, CI: 1.28-3.38) and depression (OR = 3.13, IC = 1.45-6.45). Conclusion: In spite of receiving treatment with levothyroxine, women with hypothyroidism are more likely to have depression and anxiety. Health professionals need to assess the mood of women with hypothyroidism. Although levothyroxine is a good treatment for the symptoms of hypothyroidism, it may not be enough to prevent development or persistence of depression and anxiety by itself.

Associations of Elevated Antithyroperoxidase Antibodies with Thyroid Function, Survival, Functioning, and Depressive Symptoms in the Oldest Old: The Leiden 85-plus Study

Background: Elevated levels of antithyroperoxidase antibodies (TPOAbs) have been associated with progression of subclinical thyroid dysfunction, extrathyroidal diseases, and decrease in functional status. However, TPOAb as determinant of future thyroid dysfunction and other clinical outcomes has not been studied well for adults aged 85 years and over. This study aimed to assess associations of TPOAb levels with thyroid function, survival, physical function, disability in activities of daily living (ADL), cognitive function, and depressive symptoms in the oldest old. Methods: Data from a population-based cohort study (Leiden 85-plus Study) of residents of Leiden, the Netherlands, aged 85 and older were used. Baseline serum TPOAb levels were available for 488 participants (82% of the total cohort). We considered levels ≥35 IU/mL as elevated. Thyroid function (thyrotropin [TSH] and free thyroxine) was assessed at age 85 (baseline), 87, and 88 years. Survival, physical function, disability in ADL, cognitive function, and depressive symptoms were assessed from age 85 through 90 years. Results: At baseline, 64 of the 85-year old participants (13.1%) had elevated TPOAb levels. They were more often female, had higher TSH levels, and a higher prevalence of overt or subclinical hypothyroidism than participants with normal TPOAb levels. Over time, elevated TPOAb levels were independently associated with a lower mortality risk (hazard ratio 0.72, [95% confidence interval 0.53-0.99]), but were not associated with changes in thyroid function, nor with physical function, disability in ADL, cognitive function, or depressive symptoms. Conclusions: In community-dwelling oldest old, elevated TPOAb levels are cross-sectionally associated with higher TSH levels. Over time, elevated TPOAb levels are associated with a survival benefit but are not associated with changes in thyroid function, functional status, or depressive symptoms in old age. The added clinical value of TPOAb tests in oldest old persons with thyroid dysfunction is limited.

Naming difficulties after thyroid stimulating hormone suppression therapy in patients with differentiated thyroid carcinoma: a prospective cohort study

BACKGROUND

Thyroid stimulating hormone (TSH) suppression therapy after differentiated thyroid carcinoma surgery causes cognitive impairment. However, data on naming difficulties (anomia)-related specific cognitive impairment are lacking.

METHODS

A prospective cohort study was conducted, in which, patients with differentiated thyroid carcinoma and benign thyroid nodules were given oral L-T4 therapy after surgery, after meeting the criteria of TSH suppression therapy and thyroxine replacement therapy, respectively, the patients were continually given L-T4 therapy for 6 and 12 months, and then, the neuropsychological test was performed.

RESULTS

Of the 255 subjects, 212 cases (83.13%) completed all the tests, including 33 cases in the normal control group (NC group), 110 cases in the TSH suppression therapy group (TS group), and 69 cases in the thyroxine replacement therapy group (TR group). There was no significant difference in background data among the three groups (P > 0.05). The scores of mini-mental state examination, clock drawing test, digit symbol substitution test, personal history, temporal and spatial orientation, digit order relation, visual object recognition, associative learning, and color naming in the TS and TR groups were not significantly different from those in the NC group after 6 and 12 months of L-T4 therapy (P > 0.05); the scores of picture recall, visual recall, comprehension memory, and digit span forward in the TS and TR groups were notably lower than those in the NC group (P < 0.01); the scores of confrontation naming and listing the names in the TS group were significantly lower than those in the NC and TR groups, and the scores decreased with the prolongation of TSH suppression therapy (P < 0.01).

CONCLUSION

TSH suppression therapy after differentiated thyroid carcinoma surgery could lead to short-term memory impairment, attention impairment, word selection anomia, and depression, of which, word selection anomia was aggravated with the prolongation of TSH suppression therapy. Therefore, we suggested that optimal TSH goals for individual patients must balance the potential benefit of TSH suppression therapy with the possible harm from subclinical hyperthyroidism especially in low risk differentiated thyroid carcinoma patients (ClinicalTrials.gov Protocol Registration System: ClinicalTrials.gov ID NCT0266532, Registered on 21 June 2016).

The Link between Thyroid Autoimmunity, Depression and Bipolar Disorder

Depression and bipolar disorder are two major psychiatric illnesses whose pathophysiology remains elusive. Newly emerging data support the hypothesis that the dysfunction of the immune system might be a potential factor contributing to the development of these mental disorders. The most common organ affected by autoimmunity is the thyroid; therefore, the link between autoimmune thyroid disorders and mental illnesses has been studied since the 1930s. The aim of this review is to discuss the associations between thyroid autoimmunity, depression and bipolar disorder.

Heart rate response to graded exercise test of elderly subjects in different ranges of TSH levels

OBJECTIVE

Life expectancy is increasing worldwide and studies have been demonstrating that elevated serum thyroid stimulating hormone (TSH) concentration in elderly is associated with some better health outcomes. This elevation is somewhat physiological as aging. The aim of this study was to investigate the heart rate (HR) response during a graded exercise test and its recovery in healthy elderly, comparing subjects within serum TSH in the lower limit of reference range to those within the TSH in the upper limit.

SUBJECTS AND METHODS

A cross-sectional study was conducted with 86 healthy elderly aged 71.5 ± 5.1 years, with serum TSH between 0.4 - 4.0 mUl/mL. The participants were divided into two groups according to TSH level: < 1.0 mUl/mL (n = 13) and ≥ 1.0 µUI/mL (n = 73). All participants performed an ergometric test on a treadmill. The HR was recorded and analyzed at rest, during exercise and during the three minutes immediately after exercise.

RESULTS

No differences were observed in relation to HR at peak of exercise (TSH < 1.0 µUI/mL: 133.9 ± 22.5 bpm vs. TSH ≥ 1.0 µUI/mL: 132.4 ± 21.3 bpm; p = 0.70) and during the first minute of recovery phase (TSH < 1.0 µUI/mL: 122.3 ± 23.1 bpm vs. TSH ≥ 1.0 µUI/mL: 115.7 ± 18.4 bpm p = 0.33). The groups also presented similar chronotropic index (TSH < 1.0 µUI/mL: 78.1 ± 30.6 vs. TSH ≥ 1.0 µUI/mL: 79.5 ± 26.4; p = 0.74).

CONCLUSION

In this sample studied, there were no difference between lower and upper TSH level concerning HR response during rest, peak of exercise and exercise recovery.

Genome-wide analyses identify a role for SLC17A4 and AADAT in thyroid hormone regulation

Thyroid dysfunction is an important public health problem, which affects 10% of the general population and increases the risk of cardiovascular morbidity and mortality. Many aspects of thyroid hormone regulation have only partly been elucidated, including its transport, metabolism, and genetic determinants. Here we report a large meta-analysis of genome-wide association studies for thyroid function and dysfunction, testing 8 million genetic variants in up to 72,167 individuals. One-hundred-and-nine independent genetic variants are associated with these traits. A genetic risk score, calculated to assess their combined effects on clinical end points, shows significant associations with increased risk of both overt (Graves’ disease) and subclinical thyroid disease, as well as clinical complications. By functional follow-up on selected signals, we identify a novel thyroid hormone transporter (SLC17A4) and a metabolizing enzyme (AADAT). Together, these results provide new knowledge about thyroid hormone physiology and disease, opening new possibilities for therapeutic targets.

Thyroid dysfunction is a common public health problem and associated with cardiovascular co-morbidities. Here, the authors carry out genome-wide meta-analysis for thyroid hormone (TH) levels, hyper- and hypothyroidism and identify SLC17A4 as a TH transporter and AADAT as a TH metabolizing enzyme.

Clinical aspects of thyroid function during ageing

Globally, populations are ageing at a rapid rate. The increase in the number of older citizens is accompanied by an increased prevalence of thyroid dysfunction, one of the most common disorders in older people. However, the diagnosis of thyroid dysfunction in older people is hindered by several factors, including the scarcity of thyroid dysfunction symptoms in older people. We describe the physiological changes in thyroid function that occur with increasing age, focusing on literature regarding changes in thyroid function test results in older populations. We also discuss treatment considerations for clinical and subclinical thyroid dysfunction according to international guidelines for older people. Finally, we discuss the relationship between variations in thyroid function and common diseases of old age including cardiovascular disease, osteoporosis, cognitive impairment, and frailty and suggest directions for future research.

Association between subclinical thyroid dysfunction and depressive symptoms in the Korean adult population: The 2014 Korea National Health and Nutrition Examination Survey

BACKGROUND

Clinical hyper and hypothyroidism are associated with a risk for depression.

OBJECTIVES

This study was performed to investigate the association between depressive symptoms and subclinical thyroid dysfunction.

METHODS

Among the 7,550 subjects who participated in the 2014 Korea National Health and Nutrition Examination Survey, 1,763 participants without overt thyroid disease were included in this study. Serum thyroid stimulating hormone (TSH), serum free thyroxine (fT4), and depressive symptoms were analyzed based on the Patient Health Questionnaire (PHQ9).

RESULTS

The percentages of subjects with subclinical hypothyroidism and subclinical hyperthyroidism were 3.3% and 2.6%, respectively. The percentages of subjects with moderate (10-14 points), moderately severe (15-19 points), and severe (≥20 points) depression according to the distribution of PHQ-9 scores were 4.7%, 1.1%, and 0.3%, respectively. TSH, fT4, and the percentage of patients with subclinical hypothyroidism were not significantly associated with PHQ-9 score. However, the percentage of patients with subclinical hyperthyroidism increased significantly with PHQ9 score (P = 0.002). Subjects with subclinical hyperthyroidism had higher PHQ-9 scores than those with normal thyroid function (mean ± standard error [SE], 4.2 ± 0.5 vs. 2.7 ± 0.1 points, P = 0.010). More subjects with subclinical hyperthyroidism had a PHQ9 score ≥ 10 than did those with normal thyroid function (mean ± SE, 17.1 ± 3.5 vs. 5.8 ± 0.6%, P = 0.005). We performed logistic regression analyses for the presence of depressive symptoms, using age, sex, education, household income, alcohol drinking, smoking, diabetes, cerebrovascular disease history, subclinical hypothyroidism, and subclinical hyperthyroidism as variables. Subclinical hyperthyroidism was associated with the presence of clinically relevant depression (PHQ9 score ≥ 10), (odds ratio [OR], 4.04; 95% confidence interval [CI], 1.75-9.31; P = 0.001), and clinically significant depression (PHQ9 score ≥ 15), (OR, 7.05; 95% CI, 1.67-29.67; P = 0.008), respectively. However, subclinical hypothyroidism was not associated with the presence of clinically relevant depression (OR, 1.15; 95% CI, 0.39-3.38; P = 0.800), or clinically significant depression (OR, 3.35; 95% CI, 0.71-15.79; P = 0.127).

CONCLUSIONS

We demonstrated that subclinical hyperthyroidism was independently associated with depressive symptoms in the Korean general population using national cross-sectional data.

Dose Dependency and a Functional Cutoff for TPO-Antibody Positivity During Pregnancy

OBJECTIVE

To investigate a dose dependency of thyroperoxidase antibody (TPOAb) concentrations in relation to thyroid function and premature delivery and define a population-based, pregnancy-specific, functional cutoff for TPOAb positivity.

DESIGN

Individual participant meta-analysis of three prospective birth cohorts: the Amsterdam Born Children and their Development study, and the Holistic Approach to Pregnancy.

SETTING

Population-based studies in the Netherlands (2002 to 2014).

PARTICIPANTS

A total of 11,212 pregnant women (<20 weeks' gestation).

MAIN OUTCOME MEASURES

Thyrotropin (TSH) and FT4 concentrations, premature delivery.

RESULTS

In all cohorts, there was a dose-dependent positive association of TPOAb concentrations with TSH concentrations, as well as a dose-dependent negative association with FT4 concentrations during early pregnancy (all P < 0.0001). There was a dose-dependent association of TPOAb concentrations with the risk of premature delivery, which was also modified by TSH concentrations. Women with TPOAb concentrations from the 92nd percentile upward had a higher TSH and a higher risk of a TSH >2.5 mU/L (range, 19.4% to 51.3%). Stratified analyses showed that women with TPOAb concentrations below manufacturer cutoffs already had a higher risk of premature delivery, especially when TSH concentrations were high or in the high-normal range.

CONCLUSIONS

This study demonstrated a dose-dependent relationship between TPOAbs and thyroid function as well as the risk of premature delivery. Furthermore, our results indicate that the currently used cutoffs for TPOAb positivity may be too high. Furthermore, the use of a population-based cutoff for TPOAbs may identify women with a clinically relevant extent of thyroid autoimmunity and a higher risk of premature delivery but that would not be considered TPOAb positive or eligible for treatment otherwise.

The hypothalamic-pituitary-thyroid axis and personality in a sample of healthy subjects

Thyroid hormones influence various brain pathologies, including psychiatric disorders. However, the relationship between these hormones and the psychological state in the normal, non-clinical population is poorly understood. We aimed to test whether serum levels of thyroid hormones are associated with personality in the healthy population. Thyrotropin (TSH), free T3 (FT4), total and free T4 (TT4 and FT4) concentrations were measured in the blood of 104 healthy participants (44% men) aged 18-59 (M=35±9). Personality traits were assessed using the revised short versions of the Temperament and Character Inventory (TCI-140) and the NEO Five-Factor Inventory (NEO-FFI). The data were analysed by correlational, regression, extreme groups and graphical techniques, which showed significant correlations between inter-individual variations in serum thyroid hormone levels and specific aspects of personality. In particular, high serum TSH was strongly associated with higher Persistence and Self-Directedness, and negatively correlated with Harm Avoidance on the TCI-140 and Neuroticism on the NEO-FFI, thus representing a more adaptive personality profile. Furthermore, increased FT4 was associated with lower Reward-Dependence, and increased TT4 was associated with lower Cooperativeness, representing a deficit in social attachment. Our data indicate that the relationship between thyroid hormones and personality in the healthy population might be rather more complex than the results obtained in clinical samples suggest.

The Rotterdam Study: 2018 update on objectives, design and main results

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, otolaryngological, locomotor, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. Since 2016, the cohort is being expanded by persons aged 40 years and over. The findings of the Rotterdam Study have been presented in over 1500 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy ). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.

Exome-sequencing in a large population-based study reveals a rare Asn396Ser variant in the LIPG gene associated with depressive symptoms

Despite a substantial genetic component, efforts to identify common genetic variation underlying depression have largely been unsuccessful. In the current study we aimed to identify rare genetic variants that might have large effects on depression in the general population. Using high-coverage exome-sequencing, we studied the exonic variants in 1265 individuals from the Rotterdam study (RS), who were assessed for depressive symptoms. We identified a missense Asn396Ser mutation (rs77960347) in the endothelial lipase (LIPG) gene, occurring with an allele frequency of 1% in the general population, which was significantly associated with depressive symptoms (P-value=5.2 × 10^-08, β=7.2). Replication in three independent data sets (N=3612) confirmed the association of Asn396Ser (P-value=7.1 × 10^-03, β=2.55) with depressive symptoms. LIPG is predicted to have enzymatic function in steroid biosynthesis, cholesterol biosynthesis and thyroid hormone metabolic processes. The Asn396Ser variant is predicted to have a damaging effect on the function of LIPG. Within the discovery population, carriers also showed an increased burden of white matter lesions (P-value=3.3 × 10^-02) and a higher risk of Alzheimer's disease (odds ratio=2.01; P-value=2.8 × 10^-02) compared with the non-carriers. Together, these findings implicate the Asn396Ser variant of LIPG in the pathogenesis of depressive symptoms in the general population.