Thyroid axis activity and suicidal behavior in depressed patients

Sex differences in prevalence and clinical correlates of subclinical hypothyroidism in Chinese patients with first-episode untreated major depressive disorder

BACKGROUND

Previous studies showed sex differences in the prevalences of both major depressive disorder (MDD) and subclinical hypothyroidism (SCH). This study aimed to further compare the prevalence and correlates of moderate-to-severe SCH between male and female Chinese MDD patients.

METHODS

A total of 1706 first-episode drug naïve Chinese patients with MDD were recruited. Depressive symptoms were assessed by the 17-item Hamilton Depression Rating Scale, psychotic symptoms by the Positive and Negative Syndrome Scale and anxiety symptoms by the Hamilton Anxiety Rating Scale. Serum thyroid stimulating hormone (TSH), free triiodothyronine (fT3) and free thyroxine (fT4) concentrations were measured by chemiluminescence immunoassay. Moderate-to-severe SCH was defined as serum TSH > 8 mIU/L with normal fT4.

RESULTS

The prevalence of moderate-to-severe SCH was 10.4% in male patients and 15.1% in female patients (χ2 = 7.22, p < 0.01). In female patients, binary logistic regression showed that systolic blood pressure (SBP), suicide attempts and psychotic symptoms (all p < 0.001) were associated with moderate-to-severe SCH. In male patients, SBP and psychotic symptoms were associated with moderate-to-severe SCH (both p < 0.001), while suicide attempts and severe anxiety were not (p > 0.05).

CONCLUSIONS

Our findings reveal a higher prevalence rate of moderate-to-severe SCH in female untreated first-episode MDD patients compared with males. Moreover, there is a positive association between suicide attempts and moderate-to-severe SCH only in female MDD patients.

A cross-sectional study of non-suicidal self-injury in adolescent depression: association with demographic characteristics and physiological indicators

Introduction

Non-suicidal self-injury (NSSI) is a prevalent concern among adolescents with depression, yet its relationship with demographic characteristics and physiological indicators remains underexplored. This study aimed to investigate these relationships among inpatient adolescents aged 13 to 18 at a hospital affiliated with Guizhou Medical University.

Methods

A cross-sectional study was conducted involving 222 adolescent inpatients diagnosed with depression. Data on NSSI occurrence, demographic variables (gender, only-child status, age), and physiological indicators (ALT, TSH, FT4, PLR, TG, HDLC, LDLC, FT3, NLR, MLR) were collected and analyzed. Statistical analyses, including correlations and group comparisons, were performed to assess the associations between NSSI and these factors.

Results

The prevalence of NSSI among the participants was 40.5%. Significant correlations were found between NSSI and several demographic and physiological factors. Specifically, NSSI was significantly associated with female gender, non-only-child status, younger age, lower ALT levels, higher TSH levels, lower FT4 levels, and higher PLR values. However, no significant differences were observed in TG, HDLC, LDLC, FT3, NLR, or MLR between the NSSI and non-NSSI groups.

Discussion

The findings highlight distinct demographic and physiological profiles associated with NSSI among adolescents with depression. The prevalence rate of NSSI underscores its significance as a behavioral manifestation in this population. Further research should explore the underlying mechanisms linking these factors to better inform targeted interventions and treatment strategies for adolescents experiencing NSSI in the context of depression.

Sex differences in correlates of suicide attempts in Chinese Han first-episode and drug-naïve major depressive disorder with comorbid subclinical hypothyroidism: A cross-sectional study

BACKGROUND

This study aimed to investigate sex differences in risk factors for suicide attempts in first-episode and drug naive (FEDN) major depressive disorder (MDD) with comorbid subclinical hypothyroidism (SCH).

METHODS

A total of 1034 FEDN MDD patients with comorbid SCH were enrolled. The Hamilton Depression Scale (HAMD), Hamilton Anxiety Scale (HAMA), and Positive and Negative Syndrome Scale (PANSS) positive subscale were used to assess patients' symptoms. Thyroid hormone levels and metabolic parameters were measured.

RESULTS

MDD patients with SCH had a significantly higher risk of suicide attempts than those without SCH (25.4% vs. 12.2%). Logistic regression showed that HAMA score, thyroid stimulating hormone (TSH) levels, and thyroid peroxidase antibody (TPOAb) levels were significantly associated with an increased risk for suicide attempts in both male and female MDD patients comorbid SCH, while low-density lipoprotein cholesterol (LDL-C) was significantly associated with an increased risk for suicide attempts only in male patients, HAMD score and systolic blood pressure were significantly associated with an increased risk for suicide attempts only in female patients.

CONCLUSION

SCH comorbidities may increase suicide attempts in MDD patients. Our results showed significant sex differences in clinical and metabolic factors associated with suicide attempts among FEDN MDD patients with comorbid SCH, highlighting appropriate sex-based preventive interventions are needed.

Thyroid allostasis in drug-free affective disorder patients

AIM

To assess the thyroid allostasis in drug-free patients with affective disorder.

METHODS

Patients with major depressive disorder or bipolar disorder as drug-free, defined as those without psychiatric drugs exposure for at least 4 months before admission, from a tertiary hospital were recruited in this cross-sectional study. The primary outcomes were "structure parameters of thyroid homeostasis", which include "thyroid's secretory capacity" (SPINA-GT), "sum step-up activity of deiodinases" (SPINA-GD), the ratio of total to free thyroxine and "thyroid homeostasis central set point" (TSH index and "thyroid feedback quantile-based index" [TFQI]), calculated by TSH and thyroid hormones measured at admission. A healthy population and non-affective psychiatric disorder (schizophrenia) from the same catchment area were recruited as two comparison groups.

RESULTS

A total of 1263 cases of major depressive disorder, 1619 cases of bipolar disorder, 1186 cases of schizophrenia, and 162 healthy controls were included in the study. Compared to healthy control, GD and ratio of total to free thyroxine were lower in affective disorders. Bipolar with mania episode had higher GT than bipolar with depressive episode and major depressive disorder (median level at 3.70 vs. 3.04 and 3.03, respectively). Compared with healthy control, schizophrenia had higher TSH index and TFQI, but no increase in these parameters in major depressive disorder and bipolar disorder.

CONCLUSION

Affective disorders have a unique profile of thyroid allostasis with impaired step-up deiodinase activity and reduced serum protein binding of thyroid hormones, but no change in thyroid homeostasis central set point. Mania episode may be associated with higher thyroid secretory capacity.

Clinical characteristics of suicidal behavior in first hospitalization and drug-naïve patients with major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is a major and common cause of suicide. The purpose of this article is to report the clinical characteristics and patterns of co-morbid suicidal behavior (SB) in first hospitalized and drug-naïve MDD patients.

METHODS

A total of 345 patients with first hospitalization and drug-naïve MDD with SB were included in this study, while 183 patients without SB were included as a control group. We collected socio-demographic, general clinical data and common biochemical indicators of all participants and assessed their clinical symptoms.

RESULTS

Compared to patients without SB, MDD with SB had more severe clinical symptoms and worse metabolic indicators. Duration of disease, depressive symptom scores, and thyroid stimulating hormone (TSH) levels was risk factors for SB and its number.

CONCLUSIONS

MDD patients with SB suffered more severe clinical symptoms and worse metabolic indicators, and risk factors for SB in this population were identified, which may provide beneficial insight and reference for clinical prevention and intervention of SB in MDD patients.

Sex-differential association of suicide attempts with thyroid dysfunction in first-episode and drug-naïve young major depressive disorder patients with comorbid anxiety

This study aimed to explore sex differences in the relationship between thyroid function indicators and suicide attempts in first-episode and drug-naïve young major depressive disorder (MDD) patients with comorbid anxiety (MDA). A total of 917 MDD patients (aged 18-35 years) were recruited. The Hamilton depression rating scale (HAMD-17), Hamilton anxiety rating scale (HAMA), positive and negative syndrome scale (PANSS) positive subscale and clinical global impression of severity scale (CGI-S) were used. 467 patients were classified as MDA. The prevalence of suicide attempts was 31.3% in MDA patients, which was significantly higher than that (7.3%) in MDD patients without anxiety. Compared with MDA patients without suicide attempts, MDA patients with suicide attempts were older, had a later age of onset, higher HAMD-17, HAMA, and PANSS positive symptom subscale scores, as well as higher TSH, TgAb and TPOAb levels. For male patients, TSH and TPOAb levels were independently associated with suicide attempts. For female patients, HAMA, PANSS positive symptom scores, CGI-S score and TPOAb levels were independently associated with suicide attempts. Our results suggest that the indicators of thyroid function which can predict suicide attempts in male and female MDA patients have sex differences.

Clinical correlates of autoimmune thyroiditis and non-autoimmune hypothyroidism in treatment-naïve patients with major depressive disorders

BACKGROUND

Thyroid autoimmunity is a potentially critical factor that is often neglected in the association between subclinical hypothyroidism (SCH) and depressive disorders. This study aimed to investigate the clinical correlates of autoimmune thyroiditis (AIT) and non-autoimmune hypothyroidism (NAIH) in treatment-naïve patients with major depressive disorder (MDD).

METHOD

Using a cross-sectional design, we recruited a total of 1718 outpatients with treatment-naïve MDD. Demographic and relevant clinical information including duration of MDD, severity of depression and anxiety, psychotic symptoms, suicide attempts, thyroid function parameters, etc. were collected. According to thyroid function parameters, patients were classified as AIT, NAIH, latent Hashimoto's thyroiditis (LH) and euthyroidism (ET).

RESULTS

Patients with SCH (including AIT and NAIH) had older age at onset, and were more likely to have psychotic symptoms compared to those with ET. Multiple linear regression analysis showed that SCH was associated with duration of MDD and HAMD scores. Logistic regression analysis showed that the odds of having more severe anxiety and metabolic syndrome were greater among patients with SCH compared to those with ET. The odds of having suicide attempts were greater among patients with AIT than among those with ET.

LIMITATION

Because of the cross-sectional design of this study, we were unable to sort out causality between MDD and SCH.

CONCLUSION

Our findings suggested that AIT and NAIH were associated with duration of MDD, HAMD scores, severity of anxiety, and metabolic syndrome. However, only AIT in SCH was associated with suicide attempts.

Hypothalamic-prolactin axis regulation in major depressed patients with suicidal behavior

BACKGROUND

So far, little is known about the control of hypothalamic-prolactin axis activity by dopamine (DA) and thyrotropin-releasing hormone (TRH) in depressed patients with suicidal behavior disorder (SBD).

METHODS

We evaluated prolactin (PRL) responses to apomorphine (APO; a DA direct receptor agonist) and 0800 h and 2300 h protirelin (TRH) tests in 50 medication-free euthyroid DSM-5 major depressed inpatients with SBD (either current [n = 22], or in early remission [n = 28]); and 18 healthy hospitalized controls (HCs).

RESULTS

Baseline (BL) PRL levels were comparable across the three diagnostic groups. SBDs in early remission did not differ from HCs regarding PRL suppression to APO (PRLs), PRL stimulation to 0800 h and 2300 h TRH tests (∆PRL), and ∆∆PRL values (difference between 2300 h-∆PRL and 0800 h-∆PRL values). Current SBDs showed lower PRLs and ∆∆PRL values than HCs and SBDs in early remission. Further analyses revealed that current SBDs with a history of violent and high-lethality suicide attempts were more likely to exhibit co-occurrence of low ∆∆PRL and PRL_S values.

CONCLUSIONS

Our results suggest that regulation of the hypothalamic-PRL axis is impaired in some depressed patients with current SBD, particularly those who have made serious suicide attempts. Considering the limitations of our study, our findings support the hypothesis that decreased pituitary D2 receptor functionality (possibly adaptive to increased tuberoinfundibular DAergic neuronal activity) together with decreased hypothalamic TRH drive might be a biosignature for high-lethality violent suicide attempts.

Metabolic parameters and thyroid hormones in relation to suicide attempts in patients with first-episode and drug-naive major depressive disorder with comorbid glucose disturbances: a large cross-sectional study

The factors associated with suicide attempts in major depressive disorder (MDD) patients with comorbid glucose disturbances remain unclear. To the best of our knowledge, this is the first study with a large sample size to examine risk factors of suicide attempts in first-episode drug-naïve (FEDN) MDD patients with comorbid glucose disturbances, including clinically relevant factors, metabolic parameters, and thyroid hormone levels. A total of 1718 FEDN MDD patients were enrolled. The Hamilton Depression Scale (HAMD), Hamilton Anxiety Scale (HAMA), and Positive and Negative Syndrome Scale (PANSS) were used to assess the clinical symptoms of patients. Fasting blood glucose, metabolic parameters, and thyroid hormone levels were measured. After controlling for HAMA and HAMD scores, the suicide attempt rate was 1.88 times higher in MDD patients with glucose disturbances than in MDD patients without glucose disturbances. Compared to non-suicide attempters, suicide attempters among the MDD patients with glucose disturbances had higher scores on HAMD and HAMA, PANSS positive symptoms, as well as higher levels of systolic and diastolic blood pressure, TC, LDL-C, thyroid stimulating hormone (TSH), TgAb, and thyroid peroxidases antibody (TPOAb). The combination of positive symptom score, HDL-C, systolic blood pressure, and marital status distinguished suicide attempters from non-suicide attempters. In addition, HAMA score, HAMD score, and TPOAb were associated with the number of suicide attempts in MDD patients with comorbid glucose disturbances. Our results suggest a high incidence of suicide attempts in MDD patients with comorbid glucose disturbances. Several clinically relevant factors, metabolic parameters, and thyroid hormone function have an impact on suicide attempts in MDD patients with comorbid glucose disturbances.

Suicide attempt rate and the risk factors in young, first-episode and drug-naïve Chinese Han patients with major depressive disorder

BACKGROUND

In recent years, the rates of suicide among young people have been increasing, and major depressive disorder (MDD) is regarded to be its main cause. Many factors such as thyroid dysfunction and metabolic abnormalities are thought to mediate this process, but the conclusions are inconsistent. This study investigated the rate of suicide attempts and associated risk factors among young, first-episode and drug-naïve Chinese Han patients with MDD.

METHODS

A total of 917 patients with MDD (aged 18 ~ 35 years) were recruited. Demographic and clinical data were collected and thyroid function, fasting blood glucose and lipid profiles were measured. The Hamilton Depression Rating Scale-17 items (HAMD-17), Hamilton Anxiety Rating Scale (HAMA), positive symptom subscale of Positive and Negative Syndrome Scale (PANSS) and clinical global impression of severity scale (CGI-S) were adopted to assess depression, anxiety, psychotic symptoms and disease severity respectively.

RESULTS

The rate of suicide attempts was 19.5% in young MDD patients. There were significant differences in age (p = 0.003), education level (p = 0.001), age of onset (p = 0.004) and disease duration (p = 0.001) between patients with and without suicide attempts. Compared with patients without suicide attempts, patients with suicide attempts had significantly higher scores on the HAMD-17, HAMA, PANSS positive symptom subscale and CGI-S (all p < 0.001). Patients with suicide attempts had significantly higher levels of TSH (p < 0.001), TgAb (p = 0.004), TPOAb (p < 0.001), TG (p = 0.016), TC (p < 0.001), LDL (p < 0.001), and fasting glucose (p < 0.001), but significantly lower levels of HDL (p < 0.001). Logistic regression analysis showed that marital status (OR = 0.515, 95%CI: 0.280-0.950, p = 0.515), disease duration (OR = 1.100, 95%CI: 1.013-1.194, p = 0.024), HAMA score (OR = 1.313, 95%CI: 1.205-1.430, p < 0.001), CGI-S score (OR = 1.875, 95%CI: 1.339-2.624, p < 0.001), levels of FT3(OR = 0.717, 95%CI: 0.536-0.959, p = 0.025), TPOAb (OR = 1.004, 95%CI: 1.002-1.006, p < 0.001), TC (OR = 1.330, 95%CI: 1.011-1.750, p = 0.042) and LDL (OR = 0.736, 95%CI: 0.558-0.971, p = 0.030) were all independently associated with suicide attempts in young MDD patients.

CONCLUSIONS

In China, the rate of suicide attempts in young patients with MDD is quite high and thyroid dysfunction and metabolic abnormalities may be implicated in its pathogenesis.

Blood hormones and suicidal behaviour: A systematic review and meta-analysis

This study was to evaluate the relationship between blood hormone levels and suicidal behaviour. We reviewed Web of Science, PubMed and Embase for literature published up to 10 April 2022. Studies were restricted to English-language articles. Studies measuring blood hormone levels in suicidal and non-suicidal subjects were eligible. Standardized mean differences (SMDs) were applied to evaluate group differences. Overall, 57 studies were eligible, of which 51 evaluated suicide attempts, and 9 assessed suicidal ideation. Random-effects meta-analysis indicated that levels of thyrotropin stimulating hormone (TSH) (SMD = 0.50; 95% CI, 0.27-0.72), leptin (SMD = -1.16; 95% CI, -1.94 to -0.38) and dehydroepiandrosterone sulfate (DHEAS) (SMD = -0.67; 95% CI, -1.13 to -0.21) were related to suicide attempts, whereas progesterone levels (SMD = 0.22; 95% CI, 0.03-0.41) were related to suicidal ideation. This analysis offers evidence linking abnormalities of blood hormones with suicidal behaviour, which may be essential for identifying individuals with suicide attempts and suicidal ideation. Large prospective studies are needed for further clarification of roles of hormones in suicidal behaviour.

Dopamine Function and Hypothalamic-Pituitary-Thyroid Axis Activity in Major Depressed Patients with Suicidal Behavior

Involvement of the dopaminergic (DA) and hypothalamic-pituitary-thyroid (HPT) systems in suicidal behavior is still poorly understood. We assessed multihormonal responses to apomorphine (APO; a short acting DA receptor agonist) and 8 AM and 11 PM protirelin (TRH) tests in 30 medication-free DSM-5 euthyroid major depressed inpatients with suicidal behavior disorder (SBD) (current, n = 14; in early remission, n = 16) and 18 healthy hospitalized control subjects (HCs). Compared to HCs, responses to APO and TRH tests were unaltered in SBDs in early remission. However, current SBDs exhibited increased APO-induced growth hormone (GH) and adrenocorticotropin (ACTH) stimulation, and reduced 11 PM thyrotropin (TSH) and ∆∆TSH values (difference between 11 PM and 8 AM TRH-TSH responses). In current SBDs, the association between high APO-GH concentrations and low ∆∆TSH values was more common in recent suicide attempters than in past suicide attempters. These preliminary results suggest that co-occurring alterations in the DA and HPT systems (i.e., DA receptor hyperresponsiveness associated with decreased hypothalamic TRH drive) may contribute to the pathophysiology of suicidal behavior. Conversely, normalization of DA and TRH functions might reflect a process of recovery from suicidality. Thus, our findings suggest that drugs targeting the DAergic and TRH systems could be relevant in suicide prevention.

Hypothalamic-pituitary-thyroid axis function in female adolescent nonsuicidal self-injury and its association with comorbid borderline personality disorder and depression

OBJECTIVES

Behavioral disturbances in adolescence are potentially linked to aberrant functioning of the thyroid gland. Accordingly, alterations of the hypothalamic-pituitary-thyroid (HPT) axis might impact psychopathological development. Yet corresponding research in adolescents with nonsuicidal self-injury (NSSI) and comorbid mental disorders is scarce.

METHODS

The present study examined HPT axis functioning in adolescents with NSSI compared to healthy controls (HC) using blood-based assays of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), and the ratio of these hormones (fT3/fT4 ratio). Cortisol was additionally examined to contrast HPT axis functioning with a well-established biomarker of stress responsivity. Moreover, associations between clinical characteristics, HPT axis and HPA axis functioning were investigated. Female adolescents meeting NSSI criteria according to DSM-5 criteria (n = 117) were compared to adolescent HC (n = 41). Standardized serum-based endocrinological assays and interview- and questionnaire-based psychiatric assessments were used. Smoking status was included as covariate for all analyses.

RESULTS

NSSI patients displayed altered HPT axis functioning as fT3/fT4 ratio values were blunted in comparison to HC. Negative correlations were further present between fT3, fT3/fT4 ratio and severity of BPD symptoms, depression scores and symptomatic distress. TSH correlated negatively with severity of BPD symptoms and symptomatic distress exclusively. Cortisol values differed neither significantly between experimental groups nor correlated significantly with clinical characteristics.

CONCLUSIONS

Longitudinal examinations, assessing links between psychopathology and endocrinological alterations, are warranted to address potential clinical implications of thyroid markers in child and adolescent psychiatry.

Association of Thyroid Function with Suicidal Behavior: A Systematic Review and Meta-Analysis

Thyroid disease is a very common condition that influences the entire human body, including cognitive function and mental health. As a result, thyroid disease has been associated with multiple neuropsychiatric conditions. However, the relationship between thyroid dysfunction and suicide is still controversial. We conducted a systematic review and meta-analysis to describe the association of thyroid function with suicidal behavior in adults. We searched four data bases (MEDLINE, EMBASE, PsycINFO, and Scopus) from their inception to 20 July 2018. Studies that reported mean values and standard deviation (SD) of thyroid hormone levels [Thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), total thyroxine (TT4), and total triiodothyronine (TT3)] in patients with suicidal behavior compared with controls were included in this meta-analysis. The abstracts and papers retrieved with our search strategies were reviewed independently and in duplicate by four reviewers for assessment of inclusion criteria and data extraction, as well as for evaluation of risk of bias. Random-effects models were used in this meta-analysis to establish the mean difference on thyroid function tests between groups. Overall, 2278 articles were identified, and 13 studies met the inclusion criteria. These studies involved 2807 participants, including 826 participants identified with suicidal behavior. We found that patients with suicide behavior had lower levels of FT3 (-0.20 pg/mL; p = 0.02) and TT4 (-0.23 µg/dL; p = 0.045) compared to controls. We found no differences in either TSH, FT4, or TT3 levels among groups. With our search strategy, we did not identify studies with a comparison of overt/subclinical thyroid disease prevalence between patients with and without suicide behavior. The studies included in this meta-analysis had a low-to-moderate risk of bias. In the available literature, the evidence regarding the association of thyroid disorders and suicidal behavior is limited. We found that patients with suicidal behavior have significantly lower mean FT3 and TT4 levels when compared to patients without suicidal behavior. The clinical implications and pathophysiologic mechanisms of these differences remain unknown and further research is needed.

Role of Oxidative Stress and the Identification of Biomarkers Associated With Thyroid Dysfunction in Schizophrenics

Background: Schizophrenia is associated with a deficiency of dietary antioxidants like vitamin B6, B9, and B12 resulting in defective methylation leading to hyperhomocysteinemia. Hyperhomocysteinemia causes mitochondrial DNA damage, oxidative stress, vascular damage, and lipid peroxidation. Oxidative stress and increase in reactive oxygen species result in 8-oxodG production which induces apoptosis of both astrocytes and thyrocytes thus predisposing them to thyroid dysfunction and neurodegeneration. Furthermore, the presence of excessive free radicals increases thyroid thermogenesis causing hyperthyroidism or its excess may cause hypothyroidism by inhibiting iodide uptake. In the present study, we evaluated the various biomarkers associated with thyroid dysfunction in schizophrenics. Materials and Methods: 288 patients suffering from schizophrenia and 100 control subjects were screened for liver function tests (LFTs) such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and total bilirubin (TB). Also, the stress markers, namely malondialdehyde (MDA), homocysteine, cysteine, methionine, the thyroid profile including triiodothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH), thyroxine peroxide antibody (TPO-Ab); TSH receptor-Ab (TSHr-Ab), dietary antioxidants, lipids, cytokines, aminoacids and hormones, vitamins and trace elements, and other biochemical parameters. Results: The LFTs showed elevated levels of ALT (45.57 ± 4.87 Vs. 26.41 ± 3.76 U/L), AST (40.55 ± 1.34 Vs. 21.92 ± 3.65 U/L), ALP (121.54 ± 4.87 Vs. 83.76 ± 5.87 U/L), and total bilirubin (2.63 ± 0.987 Vs. 1.10 ± 0.056 mg/dl), in schizophrenics than controls. Increased levels of MDA (3.71 ± 0.967 Vs. 1.68 ± 0.099) and homocysteine (17.56 ± 2.612 Vs. 6.96 ± 1.987 μmol/L were observed in schizophrenics compared to the controls, indicating increased stress. Levels of cysteine and methionine were decreased in schizophrenics than the controls (1.08 ± 0.089 Vs. 4.87 ± .924 μmol/L and 17.87 ± 1.23 Vs. 99.20 ± 5.36 μmol/L). The levels of TPO-Ab (IU/ml), Tg-Ab (pmol/L), and TSHr-Ab (IU/L) were observed to be higher in the patients' group as compared to control subjects (9.84 ± 2.56 Vs. 5.81 ± 1.98, 55.50 ± 2.98 Vs. 32.95 ± 2.87 and 2.95 ± 0.0045 Vs. 1.44 ± 0.0023 respectively). Levels of Vitamin B6, B9, and B12 were also significantly decreased in the patients compared to the healthy controls. Conclusion: The schizophrenics, demonstrated altered liver function, increased stress markers, and decreased dietary antioxidants. Reduced primary and secondary antioxidant levels, may result in hyperhomocysteinemia and cause further DNA and mitochondrial damage. Therefore, homocysteine and/or prolactin levels may serve as candidate prognostic markers for schizophrenia. Also, both neurological symptoms and the susceptibility to thyroid disorders may be prevented in the initial stages of this debilitating disorder by appropriate dietary supplementation of antioxidants which can rectify a reduction in primary and secondary antioxidants, and disturbed prolactin-serotonin-dopamine interactions in schizophrenics.

The association of clinical correlates, metabolic parameters, and thyroid hormones with suicide attempts in first-episode and drug-naïve patients with major depressive disorder comorbid with anxiety: a large-scale cross-sectional study

The associated factors of suicide attempts in patients with major depressive disorder (MDD) comorbid with anxiety remains unclear. To the best of our knowledge, this is the first study with a large sample size that examines the risk factors of suicide attempts in first-episode drug-naïve (FEND) MDD patients comorbid with anxiety and includes clinical correlates, metabolic parameters, and thyroid hormone levels. A total of 1718 FEDN MDD patients were enrolled. The Hamilton Depression Scale (HAMD), Hamilton Anxiety Scale (HAMA), and Positive and Negative Syndrome Scale (PANSS) were used to assess the symptoms of patients. Metabolic parameters and thyroid hormone levels were measured. The prevalence of suicide attempts in MDD patients comorbid anxiety symptoms was 24.28%, which was 9.51 times higher than that in MDD patients without anxiety symptoms (3.25%). Compared to non-attempters, MDD patients with anxiety symptoms who attempted suicide scored higher on HAMD and HAMA, and had higher systolic blood pressure, higher levels of thyroid stimulating hormone (TSH), and thyroid peroxidases antibody (TPOAb), which were also correlated with suicide attempts in MDD patients comorbid anxiety symptoms. The combination of HAMA score, HAMD score, and TSH could differentiate suicide attempters from non-suicide attempters. Further, the age of onset, illness duration, BMI, TSH, and TPOAb were associated with the times of suicide attempts in MDD patients comorbid anxiety symptoms. Our results demonstrate high prevalence of suicide attempts in MDD patients comorbid anxiety symptoms. Several clinical correlates, metabolic parameters, and thyroid hormones function contribute to the suicide attempts in MDD patients comorbid anxiety symptoms.

Comparison of Thyroid Hormone Levels Between Patients With Major Depressive Disorder and Healthy Individuals in China

Abnormal thyroid function in major depressive disorder (MDD) has been studied extensively, but the results still remain inconsistent. In China, few large-scale studies have investigated the differences in the levels of thyroid hormones between patients with MDD and healthy controls (HCs). In this retrospective, cross-sectional study, 535 MDD patients and 998 HCs were included. We compared the levels of thyroid hormones (FT3, FT4, and TSH) between the two groups, as well as investigated the distribution of levels of thyroid hormones within and outside normal ranges. The results showed that all the three hormones were significantly lower in MDD patients than in HCs, which was also true in different gender and age subgroups. The proportion of subjects with levels of all the three hormones outside the normal range in the MDD group was higher than that in the HC group (all p < 0.05). However, no significant difference was found in clinical/subclinical hyperthyroidism or hypothyroidism between the two groups (p > 0.05). Our study showed that the levels of thyroid hormones were lower in MDD patients, suggesting that there was an association between abnormal thyroid function and depression. The higher rate of thyroid dysfunction in MDD patients indicated the importance of regular monitoring of thyroid function.

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.

Association of thyroid dysfunction with suicide attempts in first-episode and drug naïve patients with major depressive disorder

BACKGROUNDS

Thyroid dysfunction was reported to be associated with depression; however, its role in suicide risk in patients with major depressive disorder (MDD) remains unclear. The objective of this study was to compare thyroid function between suicide attempters and non-suicide attempters in a large sample of first episode drug naïve (FEDN) MDD patients, which received little systemic investigation.

METHODS

A total of 1718 outpatients with diagnosis of MDD at their first episode were recruited. Their socio-demographic, clinical data and thyroid function parameters were collected. The positive subscale of the Positive and Negative Syndrome Scale (PANSS), Hamilton Anxiety Rating Scale (HAMA) and Hamilton Depression Rating Scale (HAMD) were measured for psychotic, anxiety and depressive symptoms, respectively.

RESULTS

Our results showed that compared with non-suicide attempters, suicide attempters had greater scores on HAMD, HAMA and PANSS psychotic symptoms and higher serum levels in thyroid stimulating hormone (TSH), anti-thyroglobulin (TgAb) and thyroid peroxidases antibody (TPOAb) (all p < 0.001). Further logistic regression analysis indicated that suicide attempts were associated with severe anxiety with an adjusted odds ratio (OR) of 2.704 and TPOAb with an adjusted OR of 2.188.

LIMITATIONS

No causal relationship could be drawn due to the cross-sectional design.

CONCLUSIONS

Our results indicate TSH, TgAb and TPOAb may be promising biomarkers of suicide risk in MDD, suggesting the importance of regular assessment of thyroid function parameters for suicide prevention, and possible treatment for impaired thyroid function for intervention of suicide in MDD patients.

A Case of Violent Suicide Attempt in a Context of Myxedema Psychosis following Radioiodine Treatment in a Patient with Graves' Disease

Introduction

Hypothyroidism has been associated with mood disorders but some cases of acute psychosis have also been reported. However, less attention has been paid to suicidal behavior in these patients.

Case Report

We report a case of suicide attempt by self-stabbing in a 43-year-old woman without past psychiatric history, four months after radioiodine therapy for Graves' disease. On clinical examination remarkable signs of myxedema were found and blood investigations showed hypothyroidism with an extremely high thyroid stimulating hormone (TSH) level (152 mUI/L; reference range 0.20-5.10). The patient presented delirium symptoms at the time of self-stabbing, which was associated with persecutory delusions and auditory harm command hallucinations. A rapid physical and psychiatric improvement was observed after the initiation of an oral thyroid replacement therapy without relapse after early discontinuation of the antipsychotic treatment.

Discussion

The most distinctive feature of our case is that the violent suicide attempt could be attributed to the myxedema psychosis. Suicide may result from several factors, including psychosocial stressors, psychiatric symptoms, and hormonal disturbance. This unique presentation should remind clinicians to systematically consider ordering additional tests in patients with atypical psychiatric presentation, even when serious behavioral disorders (such as violent suicide attempts) are present and may result in premature transfer to psychiatric units.

Relationship between chronobiological thyrotropin and prolactin responses to protirelin (TRH) and suicidal behavior in depressed patients

BACKGROUND

So far, investigations of the relationships between suicidality and the activity of the thyrotropic and lactotropic axes are scarce and have yielded conflicting results.

METHODS

We studied the thyrotropin (TSH) and prolactin (PRL) responses to 0800h and 2300h protirelin (TRH) stimulation tests, carried out on the same day, in 122 euthyroid DSM-5 major depressed inpatients with suicidal behavior disorder (SBD) (either current [n=71], or in early remission [n=51]); and 50 healthy hospitalized controls.

RESULTS

Baseline TSH and PRL measurements did not differ across the 3 groups. In SBDs in early remission, the TSH and PRL responses to TRH tests (expressed as the maximum increment above baseline value after TRH [Δ]) were indistinguishable from controls. Current SBDs showed (1) lower 2300h-ΔTSH and lower ΔΔTSH values (differences between 2300h-ΔTSH and 0800h-ΔTSH) than controls and SBDs in early remission; and (2) lower baseline free thyroxine (FT_4B) levels than controls. In the current SBD group, ΔΔPRL values (differences between 2300h-ΔPRL and 0800h-ΔPRL) were correlated negatively with lethality. Moreover, in current SBDs (1) violent suicide attempters (n=15) showed lower FT_4B levels, lower TSH-TRH responses (both at 0800h and 2300h), and lower ΔΔTSH and ΔΔPRL values than controls, while (2) non-violent suicide attempters (n=56) showed lower ΔΔTSH values than controls and higher TSH-TRH responses (both at 0800h and 2300h) than violent suicide attempters.

CONCLUSIONS

Our results suggest that central TRH secretion is not altered in depressed patients with SBD in early remission. The findings that current SBDs exhibit both decreased FT_4B levels and decreased evening TSH responses (and consequently, decreased ΔΔTSH values) support the hypothesis that hypothalamic TRH drive is reduced-leading to an impaired TSH resynthesis in the pituitary during the day after the morning TRH challenge. In violent suicide attempters, the marked abnormalities of TRH test responses might indicate a greatest reduction in hypothalamic TRH drive. These results further strengthen the possibility that a deficit in central TRH function may play a key role in the pathogenesis of suicidal behavior.

A hypothesis on the mechanism of action of high-dose thyroid in refractory mood disorders

Multiple lines of evidence suggest the hypothesis that high dose thyroid therapy corrects for cellular hypothyroidism found in bipolar disorders. Evidence indicates that bipolar disorders are associated with mitochondrial dysfunction which results in low cellular adenosine 5'-triphosphate (ATP) levels. Transport of thyroid hormones into cells is energy intensive and dependent on ATP except in the pituitary gland. Inadequate ATP levels makes it difficult to get thyroid hormone into cells leading to cellular hypothyroidism. This creates a condition where the blood and pituitary levels of thyroid hormone are normal but low in other tissues. High dose thyroid therapy produces a gradient that is sufficient for thyroid hormone to diffuse into cells correcting cellular hypothyroidism. If this hypothesis is correct there are number of implications. The two most important are: On average patients suffering from a bipolar disorder die 10-20years earlier than the general population. The medical sequelae associated with bipolar disorders cause far more deaths than suicide. If high dose thyroid corrects for cellular hypothyroidism it could well decrease the medical morbidity and mortality associated with bipolar disorders that are the result of cellular hypothyroidism. Thus high dose thyroid would be a first treatment that decreases the considerable medical morbidity and mortality associated with the bipolar disorders. This would stand in stark contrast to most psychiatric medications that can that increase morbidity and mortality. It would also reinforce the safety of HDT. The second implication is thyroid hormone blood levels in patients suffering from a bipolar disorder do not accurately reflect the true thyroid status.

Chronobiological hypothalamic-pituitary-thyroid axis status and antidepressant outcome in major depression

BACKGROUND

We previously demonstrated that the difference between 2300h and 0800h TSH response to protirelin (TRH) tests on the same day (ΔΔTSH test) is an improved measure in detecting hypothalamic-pituitary-thyroid (HPT) axis dysregulation in depression. This chronobiological index (1) is reduced in about three quarters of major depressed inpatients, and (2) is normalized after successful antidepressant treatment. In the present study, we examined whether early changes in HPT axis activity during the first 2 weeks of antidepressant treatment could be associated with subsequent outcome.

METHODS

The ΔΔTSH test was performed in 50 drug-free DSM-IV euthyroid major depressed inpatients and 50 hospitalized controls. After 2 weeks of antidepressant treatment the ΔΔTSH test was repeated in all inpatients. Antidepressant response was evaluated after 6 weeks of treatment.

RESULTS

At baseline, ΔΔTSH values were significantly lower in patients compared to controls and 38 patients (76%) showed reduced ΔΔTSH values (i.e., <2.5mU/L). After 2 weeks of antidepressant treatment, 20 patients showed ΔΔTSH normalization (among them 18 were subsequent remitters), while 18 patients did not normalize their ΔΔTSH (among them 15 were non-remitters) (p<0.00001). Among the 12 patients who had normal ΔΔTSH values at baseline, 8 out 9 who had still normal values after 2 weeks of treatment were remitters, while the 3 with worsening HPT axis function (i.e., reduced ΔΔTSH value after 2 weeks of treatment) were non-remitters (p<0.02). A logistic regression analysis revealed that ΔΔTSH levels after 2 weeks of treatment could predict the probability of remission (odds ratio [OR]=2.11, 95% confidence interval [CI]=1.31-3.41).

CONCLUSIONS

Our results suggest that after 2 weeks of antidepressant treatment: (1) chronobiological restoration of the HPT axis activity precedes clinical remission, and (2) alteration of the HPT axis is associated with treatment resistance.

Alterations of the daily rhythms of HPT axis induced by chronic unpredicted mild stress in rats

The relationship 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. However, the daily rhythm alteration of the functions of the hypothalamus pituitary thyroid axis (HPT) is uncertain. In the present study, we investigated the effects of chronic unpredictable mild stress (CUMS) on the daily rhythm alterations of triiodothyronine (T3), thyroxine (T4), and Thyroid Stimulating Hormone (TSH) in the plasma. We found that CUMS led to depressive-like behavior and the daily rhythm of T3, T4, and TSH in the plasma being disturbed, as well the plasma levels of T3 and T4 decreased compared to control group. Our findings indicate that CUMS not only induce hypofunction of HPT axis but also the disturbance of daily rhythm of PHT axis in rats.

Changes in 5-hydroxytryptamine and cortisol plasma levels in menopausal women after inhalation of clary sage oil

The purpose of this study was to examine the antidepressant-like effects of clary sage oil on human beings by comparing the neurotransmitter level change in plasma. The voluntary participants were 22 menopausal women in 50's. Subjects were classified into normal and depression tendency groups using each of Korean version of Beck Depression Inventory-I (KBDI-I), KBDI-II, and Korean version of Self-rating Depression Scale. Then, the changes in neurotransmitter concentrations were compared between two groups. After inhalation of clary sage oil, cortisol levels were significantly decreased while 5-hydroxytryptamine (5-HT) concentration was significantly increased. Thyroid stimulating hormone was also reduced in all groups but not statistically significantly. The different change rate of 5-HT concentration between normal and depression tendency groups was variable according to the depression measurement inventory. When using KBDI-I and KBDI-II, 5-HT increased by 341% and 828% for the normal group and 484% and 257% for the depression tendency group, respectively. The change rate of cortisol was greater in depression tendency groups compared with normal groups, and this difference was statistically significant when using KBDI-II (31% vs. 16% reduction) and Self-rating Depression Scale inventory (36% vs. 8.3% reduction). Among three inventories, only KBDI-II differentiated normal and depression tendency groups with significantly different cortisol level. Finally, clary sage oil has antidepressant-like effect, and KBDI-II inventory may be the most sensitive and valid tool in screening for depression status or severity.

Suicidal ideation and physical illness: does the link lie with depression?

OBJECTIVE

Medical illness is a risk factor for suicidality; however, disorder-specific risks are not well-known and these relationships are often explained by major depressive disorder (MDD). We aimed to investigate the relationship between suicidal ideation, MDD and medical illnesses in an age-stratified, population-based sample of men participating in the Geelong Osteoporosis Study.

METHODS

Suicidal ideation and medical conditions were self-reported. Medical conditions were confirmed by medical records, medication use or clinical data where possible. MDD was determined using the Structured Clinical Interview for DSM-IV-TR Research Version, Non-patient edition.

RESULTS

Of the 907 men, 8.5% reported suicidal ideation. Thyroid disorders (OR 3.85, 95%CI 1.2-12.1), syncope and seizures (OR 1.96, 95%CI 1.1-3.5), liver disorders (OR 3.53, 95%CI 1.1-11.8; younger men only) and alcoholism (OR 2.15, 95%CI 1.1-4.4) were associated with increased odds of suicidal ideation, independent of age and MDD. Major vascular events doubled the odds of suicidal ideation but this was explained by MDD. No association was evident with high medical burden, musculoskeletal disease, metabolic factors, gastrointestinal disorders, headaches, cardiovascular disease, COPD, cancer and psoriasis.

CONCLUSION

Health care professionals should focus on identification, assessment and management of suicidal ideation in the medically ill in patients both with and without MDD.

Two forensic autopsy cases of death from unexpected lesions of the pituitary gland

Herein, we report the findings of 2 forensic autopsy cases, in which unexpected pituitary lesions were the underlying cause of death. Case 1: A 56-year-old woman was found dead at her home during a cold winter spell. Macroscopic autopsy findings included a difference in the color of blood that filled her left and right cardiac chambers (deep red and dark red, respectively), collapse of both lungs, atrophy of the thyroid gland, and a large tumor arising from the sella turcica. Microscopic examination revealed a pituitary adenoma along with extensive bleeding. The cause of death was considered to be hypothermia, resulting from dysregulation of thermogenesis due to the pituitary adenoma. Case 2: An 86-year-old man with a history of pollakiuria was found dead in a bathtub, with his face and chest submerged in bathwater and his legs positioned outside the bathtub. The macroscopic findings of the autopsy included hyper-inflated lungs, fluid collection in the thoracic cavity, and aspiration of gastric contents in the bronchi. The atherosclerotic changes of the man's coronary and cerebral arteries were considered mild for his age. Microscopic examination showed a marked infiltration of lymphocytes and plasma cells in the posterior pituitary gland, as well as in the liver, pancreas, and submandibular gland. Considering the results of the autopsy and the findings from the investigation conducted at the death scene, we concluded that the man probably lost consciousness following a neurally mediated syncope, which was induced by diabetes insipidus (lymphocytic hypophysitis). After losing consciousness, the man likely fell in the filled bathtub and then drowned. These 2 cases highlight the need for a thorough post-mortem investigation, including a microscopic examination of the pituitary gland. In addition, forensic pathologists should carefully study the pituitary gland in cases where the cause of death is thought to be related to dysfunction of thermoregulation or osmoregulation.

What future for neuroendocrinology in psychiatry?

In psychiatry, neuroendocrine techniques were initially considered a potential "window into the brain" by indirectly marking central nervous system limbic dysfunction. At present this conception has evolved, owing to significant progress over the last decades demonstrating direct involvement of neuropeptides and neurohormones in psychiatric diseases. In a synchronic perspective, neuroendocrine investigations evaluate a functional status at a given moment in the evolution of the disease, which results from both etiopathogenic processes and compensatory homeostatic mechanisms. These vital physiological changes appear to be potential targets for novel hormonally based pharmacotherapies. However, in the past few years, the interest for the study of neuroendocrine dysregulations in psychiatric patients has declined. In order to better understand this relative disinterest, this article will attempt to shed light on strengths and limitations of the neuroendocrine approaches in psychiatry. It is necessary to bear in mind that the usefulness of these techniques in the clinical, pathophysiological and therapeutic fields depends largely on the selectivity of stimuli and the appropriateness of the methodologies used. Owing to the complexity of the clinical phenomena, multifactorial approaches (combining several neuroendocrine challenge tests to imaging, immunological, neurophysiological, neurochemical and/or genetic techniques) are to be privileged in psychiatric investigations. Despite the inherent limitations of these approaches, due to their technical and ethical constraints, the neuroendocrine strategy can inform modern clinical practice and lead to new breakthroughs in future science and practice.

Prolactin and thyroid hormone levels are associated with suicide attempts in psychiatric patients

The aim of this study is to evaluate biological factors associated with recent suicidal attempts in a naturalistic sample. A total of 439 patients suffering from major depression disorder (MDD), bipolar disorder (BD) and psychotic disorders (schizophrenia, schizoaffective disorder and psychosis not otherwise specified), who were consecutively assessed in the Emergency Department of an Italian Hospital (January 2008-December 2009), were included. In the whole sample, suicide attempters and non-attempters differed with regard to free triiodothyronine (FT3) and prolactin values only. A univariate general linear model indicated significant effects of sex (F(1;379)=9.29; P=0.002), suicidal status (F(1;379)=4.49; P=0.04) and the interaction between sex and suicidal status (F(1;379)=5.17; P=0.02) on prolactin levels. A multinomial logistic regression model indicated that suicidal attempters were 2.27 times (odds ratio (OR)=0.44; 95% confidence interval (95%CI): 0.23/0.82; P=0.01) less likely to have higher FT3 values than non-attempters; while prolactin values failed to reach statistical significance (OR=0.99; 95%CI: 0.98/1.00; P=0.051). Both prolactin and thyroid hormones may be involved in a complex compensatory mechanism to correct reduced central serotonin activity. Further studies may help in understanding how these findings can be used by clinicians in assessing suicide risk.

Biological indicators of suicide risk in youth with mood disorders: what do we know so far?

Suicidal behaviour in youth is a major public health concern worldwide, and youth in the early stages of a primary mood disorder are an identifiable high-risk population. Neurobiological research in youth at risk for suicidality has sought to investigate the most promising parameters from research in adults. The present paper provides an overview of the current findings of neurobiological research in children and adolescents with mood disorders and suicidality including genetic/epigenetic findings, neuro-hormonal and immunological investigations. Longitudinal research in high-risk youth is a powerful way to investigate the influences and their pathways in determining suicidal risk in the context of a developing mood disorder. In the meantime, there are clear clinical indicators of risk to help identify youth who would benefit from close surveillance and early intervention.

Is suicide risk correlated to thyroid weight?

Disturbances in some endocrine hormones have been implicated in the pathophysiology of depression and psychosis. We consider here further the hypothesis that there may be a correlation between suicide risk and the weight of the thyroid gland. The thyroid weight and other relevant information (sex, BMI) were collected retrospectively from 576 autopsies including 299 cases of completed suicide, analyzed in the west area of Paris between 1994 and 2010. Multiple regression model, adjusted on sex and BMI, confirmed that only for subjects more than 60 years of age, deceased by suicide, had a significant decrease in their weight of thyroid compared to those who deceased for another cause (decrease of around 3g, p=0.03, for age class 60 and over). Our hypothesis is that there could exist an anatomical correlate (thyroid weight) among people who have committed suicide, especially old individuals. Various hypotheses regarding the hypothalamus-pituitary-thyroid axis dysfunction and the physiopathology of major depression are proposed and discussed. Further studies will be necessary in order to confirm that such a tendency exists on other populations.

Identification of differentially expressed thyroid hormone responsive genes from the brain of the Mexican Axolotl (Ambystoma mexicanum)

The Mexican axolotl (Ambystoma mexicanum) presents an excellent model to investigate mechanisms of brain development that are conserved among vertebrates. In particular, metamorphic changes of the brain can be induced in free-living aquatic juveniles and adults by simply adding thyroid hormone (T4) to rearing water. Whole brains were sampled from juvenile A. mexicanum that were exposed to 0, 8, and 18 days of 50 nM T4, and these were used to isolate RNA and make normalized cDNA libraries for 454 DNA sequencing. A total of 1,875,732 high quality cDNA reads were assembled with existing ESTs to obtain 5884 new contigs for human RefSeq protein models, and to develop a custom Affymetrix gene expression array (Amby_002) with approximately 20,000 probe sets. The Amby_002 array was used to identify 303 transcripts that differed statistically (p<0.05, fold change >1.5) as a function of days of T4 treatment. Further statistical analyses showed that Amby_002 performed concordantly in comparison to an existing, small format expression array. This study introduces a new A. mexicanum microarray resource for the community and the first lists of T4-responsive genes from the brain of a salamander amphibian.