Thyroid hormones in the treatment of affective disorders

Correlation of Expression Changes between Genes Controlling 5-HT Synthesis and Genes Crh and Trh in the Midbrain Raphe Nuclei of Chronically Aggressive and Defeated Male Mice

Midbrain raphe nuclei (MRNs) contain a large number of serotonergic neurons associated with the regulation of numerous types of psychoemotional states and physiological processes. The aim of this work was to study alterations of the MRN transcriptome in mice with prolonged positive or negative fighting experience and to identify key gene networks associated with the regulation of serotonergic system functioning. Numerous genes underwent alterations of transcription in the MRNs of male mice that either manifested aggression or experienced social defeat in daily agonistic interactions. The expression of the Tph2 gene encoding the rate-limiting enzyme of the serotonin synthesis pathway correlated with the expression of many genes, 31 of which were common between aggressive and defeated mice and were downregulated in the MRNs of mice of both experimental groups. Among these common differentially expressed genes (DEGs), there were genes associated with behavior, learning, memory, and synaptic signaling. These results suggested that, in the MRNs of the mice, the transcriptome changes associated with serotonergic regulation of various processes are similar between the two groups (aggressive and defeated). In the MRNs, more DEGs correlating with Tph2 expression were found in defeated mice than in the winners, which is probably a consequence of deeper Tph2 downregulation in the losers. It was shown for the first time that, in both groups of experimental mice, the changes in the transcription of genes controlling the synthesis and transport of serotonin directly correlate with the expression of genes Crh and Trh, which control the synthesis of corticotrophin- and thyrotropin-releasing hormones. Our findings indicate that CRH and TRH locally produced in MRNs are related to serotonergic regulation of brain processes during a chronic social conflict.

Scanning of estrogen receptor alpha (ERalpha) and thyroid hormone receptor alpha (TRalpha) genes in patients with psychiatric diseases: four missense mutations identified in ERalpha gene

Estrogen and thyroid hormones exert effects on growth, development, and differentiation of the nervous system. Hormone administration can lead to changes in behavior, suggesting that genetic variants of the estrogen receptor alpha (ERalpha) and the thyroid hormone receptor alpha (TRalpha) genes may predispose to psychiatric diseases. To investigate this possibility, regions of likely functional significance (all coding exons and flanking splice junctions) of the ERalpha and TRalpha genes were scanned in patients with schizophrenia (113), along with pilot studies in patients with bipolar illness (BPI), puerperal psychosis, autism, attention-deficit hyperactivity disorder (ADHD), and alcoholism. A total of 1.18 megabases of the ERalpha gene and 1.16 megabases of the TRalpha gene were scanned with Detection of Virtually All Mutations-SSCP (DOVAM-S), a method that detects virtually all mutations. Four missense mutations, seven silent mutations and one deletion were identified in the ERalpha gene, while only four silent mutations were present in the TRalpha gene. Two of the missense mutations in ERalpha are conserved in the six available mammalian and bird species (H6Y, K299R) and a third sequence variant (P146Q) is conserved in mammals, birds, and Xenopus laevis, hinting that these sequence changes will be of functional significance. These changes were found in one patient each with BPI, puerperal psychosis, and alcoholism, respectively. Analysis of the ERalpha and TRalpha genes in 240 subjects reveals that missense changes and splice site variants are uncommon (1.7% and 0%, respectively). Further analyses are necessary to determine if the missense mutations identified in this study are associated with predisposition or outcome for either psychiatric or nonpsychiatric diseases.

Thyroid hormone, neural tissue and mood modulation

The successful treatment of affective disorders with thyroid hormone exemplifies the suggested inter-relationship between endocrine and neuronal systems in these disorders. Thyroid hormones have a profound influence on behaviour and appear to be capable of modulating the phenotypic expression of major affective illness. Specifically, there is good evidence that triiodothyronine (T3) may accelerate the antidepressant response to tricylic antidepressants, and some studies suggest that T3 may augment the therapeutic response to antidepressants in refractory depressed patients. Open studies have also indicated that adjunctive supraphysiological doses of thyroxine (T4) can ameliorate depressive symptomatology and help stabilize the long-term course of illness in bipolar and unipolar patients, especially women refractory to standard medications. Despite acceptance of the essential role of thyroid hormone on brain maturation and differentiation, and the clinical and therapeutic observations in association with mood disorders, the molecular action that may underlie the mood-modulating properties of thyroid hormone in the adult brain has only recently become the focus of research. The identification of nuclear T3 receptors, the region-specific expression of deiodinase isoenzymes and the molecular analyses of thyroid-responsive genes in the adult brain have provided the biological bases for a better understanding of thyroid hormone action in mature neurons. Also the influence of thyroid hormones on the putative neurotransmitter systems that regulate mood and behaviour, serotonin and norepinephrine, may be helpful in explaining their mood-modulating effects.

Thyroid function and response to 48-hour sleep deprivation in treatment-resistant depressed patients

BACKGROUND

Clinical depression is associated with abnormalities of the hypothalamic-pituitary-thyroid axis. Changes in thyroid function during sleep deprivation may be related to its antidepressant effects.

METHODS

Levels of thyroid-stimulating hormone, tri-iodothyronine, tri-iodothyronine uptake, thyroxine, and free thyroxine were measured before, during, and after a 48-hour sleep deprivation in nine treatment-resistant depressed patients. Clinical state was assessed every 4 hours. A retrospective study of 26 similar patients was added for cross-validation.

RESULTS

Significant increases in thyroid-stimulating hormone and tri-iodothyronine during sleep deprivation were not correlated with clinical improvement. Sleep deprivation responders had lower tri-iodothyronine uptake levels than nonresponders in both the prospective (p <.02) and the retrospective (p <.03) samples.

CONCLUSIONS

The lower tri-iodothyronine uptake values in responders may identify a subgroup of depressed patients who respond to sleep deprivation by virtue of some abnormality of the hypothalamic-pituitary-thyroid axis that is temporarily corrected by sleep deprivation.

Free thyroxine and thyroid-stimulating hormone levels in patients with seasonal affective disorder and matched controls

Seasonal affective disorder (SAD) is characterized by recurrent episodes of depression in the fall and winter that alternate with nondepressed periods in the spring and summer. Because some symptoms of SAD, such as decreased energy and weight gain, also occur in hypothyroidism, it is possible that individuals with SAD have a subtle decrease in thyroid function. To test this hypothesis, we studied blood levels of free thyroxine (T4) and thyroid-stimulating hormone (TSH) in SAD patients and matched controls in the winter. We found that free T4 blood levels were slightly but significantly lower in patients than in healthy volunteers. The difference between TSH levels in SAD patients and controls was not statistically significant. Future research will be needed to determine whether the difference in thyroid function between SAD patients and controls is an epiphenomenon or is related to the biological mechanisms that cause symptoms of SAD.

Risk of adverse events with the use of augmentation therapy for the treatment of resistant depression

Augmentation therapy is used for those situations where a patient's depression is either treatment-resistant, or partially and/or insufficiently responsive to treatment. It also may be used to attempt to induce a more rapid treatment response. Using drugs together may increase the risk of adverse effects, through potentiation of existing adverse effects or alterations in plasma concentrations of the drug. It is important that clinicians are aware of potential risks of augmentation therapy. Lithium augmentation of a tricyclic antidepressant is relatively well tolerated and the dangers are no greater than using these medications on their own. There are also no reports of serious adverse events when lithium is added to a monoamine oxidase inhibitor. With lithium augmentation of selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitor (SSRI) therapy there have been case reports of the development of a central serotonin syndrome, and thus caution must exercised. A serious concern when using a tricyclic antidepressant to augment an SSRI is the effect of the SSRI on the cytochrome P450 system and the resulting significant increase in tricyclic antidepressant blood concentrations. Augmentation with thyroid hormones appears to be well tolerated and effective. Case reports and open studies indicate that augmentation with buspirone and the psychostimulants, carbamazepine and valproic acid (valproate sodium) is effective and results in minimal adverse effects. However, there is no empirical evidence supporting these results. Recent work supports the tolerability and efficacy of pindolol augmentation. Considerable caution should be exercised when combining psychotropic drugs. The practitioner should only do so with a full knowledge of the compounds involved and their pharmacological properties.

[Non-thyroid indications of treatment with thyroid hormones]

INTRODUCTION

The use of thyroid hormone is currently strictly limited to thyroid diseases. Several recent papers have examined the effects of thyroid hormone in non-thyroidal diseases. These studies examined either the use of the pharmacological properties of thyroid hormone or the effect of the correction of the decrease in triiodothyronine (T3) associated with non-thyroid illnesses.

CURRENT KNOWLEDGE AND KEY POINTS

Intravenous administration of T3 improves the cardiac index during ongoing cardiac surgery, with a paradoxical decrease in the incidence of atrial fibrillation. T3 administered by the oral route also improves the cardiac index in the medium term in dilated cardiomyopathy. No benefit on survival has been demonstrated in non-thyroidal diseases when using the pharmacological properties of thyroid hormone. Other situations, such as transplantation or neural rescue after cardiac arrest, are currently under study. In non-thyroidal diseases, administration of thyroxine (T4) has no effect because of the deeply disturbed metabolism of thyroid hormones.

FUTURE PROSPECTS AND PROJECTS

Adverse metabolic effects of T4 and T3 therapy have probably been overestimated and may depend on the dose and on the time of administration in the course of the disease. Indications in cardiac surgery and cardiac diseases need to be clarified. To further understand the value of thyroid hormones in non-thyroidal diseases, placebo-controlled studies using small doses of T3 are required.

Women's mental health in primary care. Depression, anxiety, somatization, eating disorders, and substance abuse

Primary care physicians can improve the care of women patients by applying new concepts of women's physiology and psychosocial development. New developmental models that emphasize the importance of relationships in women's self-concept and well-being have led to effective psychotherapies for depression, eating disorders, anxiety and substance abuse. Many of these therapies can be offered in brief formats suitable to primary care settings. New biological treatments including the use of estrogen, thyroid hormone and bright light for depression and refeeding to increase metabolic rate in eating disorders also promise to expand the range of mental health problems that generalist physicians can treat successfully.

Rapid cycling bipolar affective disorder: lack of relation to hypothyroidism

Thyroid indices were measured after an extended period of medication-free evaluation averaging 6 weeks in 67 consecutively admitted patients with bipolar illness. Thyroid hormone levels -- thyroxine (T4), free T4 and triiodothyronine (T3) -- were not significantly different in the 31 rapid cyclers (> or = 4 affective episodes/year) than in 36 non-rapid cyclers. Analysis of covariance indicated a non-significant trend relation between higher T4 and a greater number of affective episodes in the year prior to admission and male gender when age was covaried. Several previous reports, primarily in medicated subjects, have suggested a link between rapid cycling patients and decreased peripheral thyroid indices (low hormone levels and elevated TSH), but now the majority of studies do not support such a relation. Among those in the literature, this study includes patients studied for the longest time off medications and further suggests that the commonly-cited relation between subclinical hypothyroidism and rapid cycling bipolar illness be reevaluated.

A review of the use of augmentation therapy for the treatment of resistant depression: implications for the clinician

OBJECTIVE

To critically review the literature on augmentation therapy in resistant depression in order to assist the clinician to make a reasoned choice. Augmentation therapy is defined as the addition of a second agent to an existing antidepressant regimen with the aim of achieving improved clinical response.

METHOD

The available literature which related specifically to currently popular augmentation strategies in treatment resistant depression for the past 20 years was examined. The scientific evidence supporting the efficacy of these regimens and their safety was reviewed.

RESULTS

Considerable research on lithium augmentation has been undertaken, and on triiodothyronine augmentation to a lesser degree. A number of other drugs have been trialed as augmentation agents with claims of success; however, most of the evidence supporting these agents is anecdotal and in the form of case reports. There are very few well-performed double-blind placebo-controlled studies of augmentation therapy.

CONCLUSIONS

Because of possible complex pharmacodynamic and pharmacokinetic interactions, augmentation therapy is not without its potential complications. Lithium augmentation of tricyclic antidepressants can be recommended as a safe and effective strategy and there is a body of scientific evidence supporting the addition of T3 as an effective augmentation agent. Recent research with pindolol augmentation of selective serotonin re-uptake inhibitors (SSRIs) is encouraging, but these findings require replication. There is no empirical evidence supporting buspirone, carbamazepine, sodium valproate, methylphenidate or amphetamine as effective augmentation agents, or that adding a tricyclic to a SSRI has usefulness in relieving depressive symptoms. There is a need for considerable research in this area, with more prospective well-controlled placebo studies.

The hypothalamic-pituitary-thyroid axis in major depression

We investigated the capacity of several thyroid-axis measures to distinguish between depressed and control subjects and determined whether these variables were related to antidepressant treatment response. We studied 105 subjects who fulfilled the DSM-III-R criteria for a current major depressive episode and 41 volunteers with no current mental disorder. The following thyroid-axis variables were measured: difference between T4 levels at 09.00 hours and 13.00 hours; baseline TSH; maximal TSH response to 400 micrograms TRH (delta max TSH); and presence of a blunted delta max TSH. The T4 difference variable alone distinguished between depressed and control subjects. In multivariate analyses, T4 difference and delta max TSH were independently related to antidepressant-treatment outcome, and predicted a modest proportion (14%) of the variance in outcome. The relationship between these two variables and treatment outcome was particularly strong in depressed male subjects who were receiving desipramine, for whom they accounted for 36% of the variance in treatment outcome. The T4 difference variable both distinguished between depressed and control subjects and was related to treatment outcome. Although this finding requires replication, it is consistent with other reports of the usefulness of thyroid-axis indices measured at different times of day in depressed patients.

Hypothalamic-pituitary-thyroid-axis function in treatment resistant depression

Recently, there were some reports that the prevalence of various grades of hypothyroidism may be increased in patients with treatment resistant depression (TRD). The aim of the present study was to examine serum basal thyroid-stimulating hormone (TSH) and thyroxine (T4) levels in 36 major depressed subjects, of whom 27 had TRD and 15 were normal volunteers. There were no significant differences in serum basal TSH or T4 levels between major depressed subjects and normal controls, or between patients with TRD versus normal controls or subjects without TRD. There was a trend towards lower serum basal T4 concentrations in patients with TRD than in other depressed patients and normal controls. One patient with TRD had basal serum TSH levels in the hyperthyroid range. Two subjects, one with TRD and one normal control, had serum TSH values in the subclinical hypothyroid zone, but their serum T4 values were in the euthyroid range. There were no significant relationships between basal TSH or T4 and severity of illness, staging of depression based on prior treatment non-response, length of the depressive episode, duration of illness, or number of previous depressive episodes. In conclusion, the results of this study do not provide evidence that (subclinical) hypothyroidism occurs more than coincidentally in depressed patients with TRD.

Management of treatment-resistant unipolar and chronically depressed patients

The majority of depressed patients presenting as treatment refractory will respond to a properly chosen new medication or to a previous agent administered correctly. Drug combinations are less frequently required than current practice would indicate, and their usage depends at present more on clinical experience than scientific fact. Educating the patient about the series of options available, and the sequence in which they will be undertaken, and imbuing the enterprise with hopeful optimism are essential ingredients to ultimate success.

The management of treatment-resistant depression in the medically ill

There are a few well-designed studies to systematically assess treatment-resistant depression in the medically ill patient. Psychiatrists, however, do have extensive clinical experience in treating depression in the medical patient. This experience can be useful in helping to determine treatment resistance and in selecting consequent treatment choices. A decision tree is offered in Table 1 to clarify the questions the clinician must answer. The first step is to evaluate the role of the medical illness and to decide whether or not treating that effectively will also clear the depression. Physicians may find it helpful to use a decision tree in initiating treatment of patients with depression and physical illness. Once it has been clarified that the diagnosis of depression is a correct one and that an antidepressant medication is in order, consideration of safety, side effects, and other current prescriptions used by the patient must occur. Drug-drug interactions as well as changes in the clearance of medications are critical to the effectiveness of the choice and tolerability for the patient. An antidepressant agent needs to be given for an adequate time with optimization of dosing. Augmenting a medication to increase its therapeutic action could be tried if one agent alone is not effective. An alternative approach is that the second drug selected might affect different neurotransmitters, and the combination of mechanisms would result in resolution of symptoms. Adding psychotherapy, especially when social supports are lacking, can be particularly helpful. ECT is an important consideration for severe depression when suicidal concerns are imminent or the patient has not responded to pharmacotherapy trials. While we await further studies of treatment-resistant depression in large enough numbers of patients with particular illnesses, we can use these guidelines to direct our decisions to switch or augment our initial choices to provide the safest, most effective care possible.

The phenomenon of rapid cycling in bipolar mood disorders: a review

OBJECTIVE

To review the various pharmacological and nonpharmacological factors associated with the induction of rapid cycling in bipolar mood disorder, and to introduce the idea that parturition may also have a role. Factors known to contribute to bipolar mood disorder rapid cycling include antidepressant agents, female gender and middle age. Currently, there is evidence that hypothyroidism may also play a role.

METHOD

A critical review of the literature was undertaken.

CONCLUSION

Caution should be exercised in the use of antidepressants in patients with bipolar mood disorders.

Effects of long term treatment with sertraline (Zoloft) simulating hypothyroidism in an adolescent

A 16-year-old depressed adolescent, who had received sertraline treatment for the previous 18 months, developed insomnia, daytime somnolence and lack of energy. His thyroid function tests revealed low levels of total T4 with normal levels of free T4 and TSH, and a normal thyrotropin-releasing hormone (TRH) stimulation test. Discontinuing sertraline resulted in improved sleep and disappearance of daytime somnolence. Although daytime somnolence and low levels of total T4 can mimic hypothyroidism, in this case sertraline only displaced the bound-fraction of total T4 and was not associated with true hypothyroidism.

The influence of DST and TRH test administration on depression assessments: a controlled study

Significant antidepressant effects have been reported after administration of dexamethasone and thyrotropin-releasing hormone (TRH). The purpose of this study was to evaluate whether or not the administration of the dexamethasone suppression test (DST) and TRH test in depressed patients, just before their entering clinical trials, has any impact on their symptoms. The Hamilton Rating Scale for Depression was administered to 166 subjects at screen visit, 1 week later (baseline visit), and 1 week after beginning treatment with fluoxetine 20 mg/day (week-1). Between screen and baseline visits, 62 patients were administered the DST alone, 6 underwent the TRH test alone, and 26 received both the DST and the TRH test. Seventy-two patients were not administered either test. No statistically significant differences in depression scores were found at screen, baseline and week-1 visits between patients who underwent neuroendocrine tests and those who did not. Our data suggest that the administration of neuroendocrine tests such as the DST and the TRH test does not have a statistically significant effect on depressive symptoms and, therefore, does not interfere with study results and interpretation.

Short-lasting behavioural effects of thyrotropin-releasing hormone in depressed women: results of placebo-controlled study

The rapid and short-lasting behavioral effects of thyrotropin-releasing hormone (TRH) were investigated in female patients with DSM-III-R major depression syndrome (MDS). Twenty-six depressed patients free of any medication received 0.2 mg of Protirelin (synthetic TRH) intravenously and 16 received placebo. All patients completed the Zung Self-Rating Depression Scale and the Spielberger State and Trait Anxiety Inventory (SSAI and STAI) twice: before and 2 hr after protirelin or placebo administration. The significant improvement in patients' emotional state after TRH injection was observed on STAI (p < .001) and SSAI (p < .01). Protireline was superior to placebo on STAI (p < .005). There was no significant correlation between behavioral effects of Protirelin and changes in thyroid hormones and TSH secretion. The improvement in patients' emotional state was more evident in depressed patients without associated panic attacks than in MDS with panic. These findings suggest that TRH has rapid positive effects on depression and that they depend more on patients' emotional state than on the function of the hypothalamus-pituitary-thyroid axis.

Comparison of thyroid function between responders and nonresponders to thyroid hormone supplementation in depression

The serum levels of thyroxine (T4), 3,5,3'-triiodothyronine (T3) and 3,3',5'-triiodothyronine (reverse T3, rT3) were examined from 8 depressed patients who did not maximally benefit from conventional antidepressant therapy. Four of the 8 depressed patients showed significant clinical improvement after thyroid hormone was added to their ongoing antidepressant drugs. The T4 and rT3 levels prior to thyroid hormone supplementation were significantly lower in responders than in nonresponders, although within the normal range. Furthermore, all of the patients who had both their rT3 levels less than 200 pg/ml and T4 levels less than 7 micrograms/dl responded to the thyroid hormone treatment. These data suggest that the lower T4 and rT3 levels can predict the treatment response to the thyroid hormone supplementation in depressed patients.

Effects of thyroid hormones on central nervous system in aging

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

Therapeutic sleep deprivation in a depressed patient: prolongation of response with concurrent thyroxine

A 53-year-old woman with major depression was studied throughout 7 trials of therapeutic sleep deprivation (SD). Under conditions where the patients was either medication-free or receiving antidepressant therapy, improvement with SD was followed by full relapse on returning to sleep. Four SD sessions conducted while the patient was receiving thyroxine each resulted in remission, sustained for several days. These results suggest that the beneficial effects of SD may be mediated by thyroid hormones, or associated activity in the hypothalamic-pituitary-adrenal axis.

Lithium discontinuers. II. Therapeutic outcome

Eleven patients from a lithium-treated cohort of 64 patients with major affective disorder (DSM-III) were investigated after a mean of 6.7 years on lithium prophylaxis and reinvestigated 7 years later, at which point they had discontinued lithium for a mean of 2.3 years. Therapeutic outcome was compared in the 11 discontinuers and 20 continuers on lithium from the same cohort, matched for sex, age, and mental status on admission to the study. Ratings of psychopathology (CPRS) at the end of the 7-year follow-up period showed that the only significant difference between the patient categories was a higher frequency of reported autonomic disturbances and worry over trifles in the discontinuers. Daily doses of neuroleptic drugs were significantly higher in discontinuers than in controls by the end of the study. Alternative concomitant treatment outside conventional medicine was sought by 45% of the discontinuers, whereas no lithium-treated control reported the need for such additional therapeutic measures.

The use of thyroid hormone in the treatment of depression: a review

The writers of this paper made an inventory of the studies on the use of thyroid hormone in the treatment of depression. Fifteen clinical trials (353 patients), published between 1969 and 1987. were found, that can be described, as to their design, in two seperate groups: One group (7 studies) administers thyroid hormone simultaneously with a tricyclic antidepressant to reach a faster effect of the antidepressant. The other group (8 studies) adds thyroid hormone to a tricyclic antidepressant in patients who fail to respond to this treatment, with the aim to convert therapeutic failure to success. After studying the literature we think we are able to conclude that it can be usefull to combine the antidepressant with thyroid hormone in view of the fact that, in a number of depressed patients, it shortens the duration of the illness. The augmentation of tricyclics by thyroid hormone needs further study.