The hypothalamic-pituitary-thyroid axis in patients maintained on lithium prophylaxis for years: high triiodothyronine serum concentrations are correlated to the prophylactic efficacy

The association between neuroendocrine/glucose metabolism and clinical outcomes and disease course in different clinical states of bipolar disorders

Objective

The treatment of bipolar disorder (BD) remains challenging. The study evaluated the impact of the hypothalamic-pituitary-adrenal (HPA) axis/hypothalamic-pituitary-thyroid (HPT) axis and glucose metabolism on the clinical outcomes in patients with bipolar depression (BD-D) and manic bipolar (BD-M) disorders.

Methods

The research design involved a longitudinal prospective study. A total of 500 BD patients aged between 18 and 65 years treated in 15 hospitals located in Western China were enrolled in the study. The Young Mania Rating Scale (YMRS) and Montgomery and Asberg Depression Rating Scale (MADRS) were used to assess the BD symptoms. An effective treatment response was defined as a reduction in the symptom score of more than 25% after 12 weeks of treatment. The score of symptoms was correlated with the homeostatic model assessment of insulin resistance (HOMA-IR) index, the HPA axis hormone levels (adrenocorticotropic hormone (ACTH) and cortisol), and the HPT axis hormone levels (thyroid stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), free triiodothyronine (fT3), and free thyroxine (fT4)).

Results

In the BD-M group, the YMRS was positively correlated with baseline T4 (r = 0.349, p = 0.010) and fT4 (r = 0.335, p = 0.013) and negatively correlated with fasting insulin (r = -0.289, p = 0.013). The pre-treatment HOMA-IR was significantly correlated with adverse course (p = 0.045, OR = 0.728). In the BD-D group, the baseline MADRS was significantly positively correlated with baseline fT3 (r = 0.223, p = 0.032) and fT4 (r = 0.315, p = 0.002), while baseline T3 (p = 0.032, OR = 5.071) was significantly positively related to treatment response.

Conclusion

The HPT axis and glucose metabolism were closely associated with clinical outcomes at 12 weeks in both BD-D and BD-M groups. If confirmed in further longitudinal studies, monitoring T3 in BD-D patients and HOMA-IR for BD-M could be used as potential treatment response biomarkers.

Exploring the potential of thyroid hormones to predict clinical improvements in depressive patients: A machine learning analysis of the real-world based study

BACKGROUND

Although undergoing antidepressant treatments, many patients continue to struggle with chronic depression episode. Seeking the potential biomarkers and establishing a predictive model of clinical improvements is vital to optimize personalized management of depression. Mounting evidence showed thyroid hormones changes are central to leading paradigms of depression.

METHODS

Here, we conducted a real-world based retrospective study using clinical and biochemical data of 2086 depressive inpatients during period of 2014-2020. We first performed regression analyses to evaluate the contributing effect of free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) in predicting the clinical outcomes of depression. Then we established 7 predictive models using different combination of such hormones by supervised learning methods and tested the actual prediction efficacy on clinical outcomes, in order to select the one with the best predictive power.

RESULTS

The results showed that lower values of FT3 and FT4 can both predict a poor clinical outcome in depression. Further, a model with the best performance was selected (sensitivity=0.91, specificity=0.79, and ROC-AUC=0.86), including the values of FT3 and FT4, and the scores of Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA) as features.

LIMITATIONS

The predictive model requires further external validation, and multi-center researches to confirm its clinical applicability.

CONCLUSIONS

Our findings present a crucial role of thyroid measurements in predicting clinical outcomes of depression. Assessment of thyroid hormone should be extended to routine practice settings to determine which patients should be most in need of earlier or intensive interventions for preventing continued dysfunction.

Thyroid functions and bipolar affective disorder

Accumulating evidence suggests that hypothalamo-pituitary-thyroid (HPT) axis dysfunction is relevant to the pathophysiology and clinical course of bipolar affective disorder. Hypothyroidism, either overt or more commonly subclinical, appears to the commonest abnormality found in bipolar disorder. The prevalence of thyroid dysfunction is also likely to be greater among patients with rapid cycling and other refractory forms of the disorder. Lithium-treatment has potent antithyroid effects and can induce hypothyroidism or exacerbate a preexisting hypothyroid state. Even minor perturbations of the HPT axis may affect the outcome of bipolar disorder, necessitating careful monitoring of thyroid functions of patients on treatment. Supplementation with high dose thyroxine can be considered in some patients with treatment-refractory bipolar disorder. Neurotransmitter, neuroimaging, and genetic studies have begun to provide clues, which could lead to an improved understanding of the thyroid-bipolar disorder connection, and more optimal ways of managing this potentially disabling condition.

Lithium and thyroid

One in 200 people receive lithium for treatment of bipolar disorder. The common clinical side effects of the drug are goitre in up to 40% and hypothyroidism in about 20%. Lithium increases thyroid autoimmunity if present before therapy. Treatment with levothyroxine is effective and lithium therapy should not be stopped. Lithium may cause hyperthyroidism due to thyroiditis or rarely Graves' disease. As lithium inhibits thyroid hormone release from the thyroid gland it can be used as an adjunct therapy in the management of severe hyperthyroidism. It also increases thyroidal radioiodine retention and may be effective in reducing administered activity in hyperthyroidism. There is no clinical benefit of lithium therapy in thyroid cancer. More research is required on the cellular proliferative effects of lithium as well as its impact on the immune system.

Differences in hypothyroidism between lithium-free and -treated patients with bipolar disorders

The majority of the previous studies of thyroid abnormalities in bipolar patients was conducted in populations containing various proportions of lithium-treated subjects. In the present study, we sought to determine whether there exist differences in hypothyroid profile between lithium-free and -treated bipolar patients. Bipolar patients never treated with lithium and carbamazepine (n=78) and those currently in lithium therapy (n=53) were included in this study. Serum concentrations of total thyroxine (T(4)), total triiodothyronine (T(3)), and thyroid-stimulating hormone (TSH) were compared between lithium-free and -treated patients. The rate of hypothyroidism in lithium-free patients was significantly lower than those treated with lithium (6.3%-10.8% vs. 28.0%-32.1%). Significant changes in the three thyroid indices indicative of hypothyroidism were consistently associated with longer illness duration in lithium-free manic patients, but with greater severity of mania and more mood episodes in their lithium-treated counterparts. In lithium-free depressed patients, more episodes were associated with lower T(4) levels; whereas in their lithium-treated counterparts, longer illness duration was associated with higher TSH levels and females with lower T(3) levels. These results suggest that bipolar patients with and without lithium exposure differ in prevalence and association of hypothyroidism and may have different response to thyroid hormone therapy.

Rapid cycling bipolar disorder: clinical characteristics and treatment options

Approximately one of six patients who seek treatment for bipolar disorder present with a rapid cycling pattern. In comparison with other patients who have bipolar disorder, these individuals experience more affective morbidity in both the immediate and distant future and are more likely to experience recurrences despite treatment with lithium or anticonvulsants. Particular care should be given to distinguishing rapid cycling bipolar disorder from attention-deficit hyperactivity disorder in children or adolescents and from borderline personality disorder in adults. Perhaps four of five cases of rapid cycling resolve within a year, but the pattern may persist for many years in the remaining patients. As with bipolar disorder in general, depressive symptoms produce the most morbidity over time. Controlled studies have not established that antidepressants provoke switching or rapid cycling, but neither have they been shown consistently to have benefits in bipolar illness. Successful management will often require a sequence of trials with mood stabilizer drugs, beginning with lithium in treatment-naive patients. Efforts to minimise adverse effects, and the recognition that full benefits may not be apparent for several months, will make the premature abandonment of a potentially helpful treatment less likely. Placebo-controlled studies so far provide the most support for the use of lithium and lamotrigine as prophylactic agents. The combination of lithium and carbamazepine, valproate or lamotrigine for maintenance has some support from controlled studies, as does the adjunctive use of olanzapine.

Efficacy of electroconvulsive therapy in treatment-resistant bipolar disorder: a case series

The response to electroconvulsive therapy for six bipolar patients after pharmacotherapy failure is discussed.

METHODS

Inclusion criteria were as follows: (1) bipolar mood disorder, manic, depressive or mixed episode (DSM-IV); (2) failure of pharmacotherapy, that is, for mania, manic episode unresponsive to at least 2 adequate antimanic trials for 6 weeks; and for bipolar depression, bipolar depressive episode unresponsive to at least 2 adequate antidepressant trials for 8 weeks. The patients underwent 12 bilateral sessions of ECT 3 times per week. Clinical response was considered a reduction of 50% or greater in the Young Mania Rating Scale (YMRS) and in the Hamilton Rating Scale for Depression-21 items (HAMD-21). Final YMRS <6 and HAMD-21 <8 defined remission.

RESULTS

Six of the 9 referred patients consented to be submitted to ECT. Four were male, with ages ranging from 29 to 61 years, and their age at onset ranged from 19 to 49 years. Four showed psychotic features. All responded to ECT.

Thyroid function and psychiatric morbidity in patients with manic disorder receiving lithium therapy

Euthyroid hyperthyroxinemia as a result of a transient increase in thyroid-stimulating hormone (TSH) levels may contribute to the development of manic disorder. Lithium has a potent short-term antithyroidal effect that may account for its antimanic action. The thyroid function and psychiatric morbidity of 46 adult patients with manic disorder were assessed prospectively before and 1 and 6 months after lithium treatment. At baseline, the free thyroxine level (FT4, 16.23 +/- 3.11 pmol/L) was at the high end of the normal range, whereas the free triiodothyronine (FT3, 4.24 +/- 0.65 pmol/L) and TSH (1.47 +/- 0.73 mIU/L) levels were within the normal range. All patients were clinically euthyroid, but five of them (11%) had elevated FT4 levels. Baseline FT3 and FT4 levels were positively correlated with past psychiatric morbidity. The FT4 level at baseline and after 1 month of treatment was positively correlated with scores on the Brief Psychiatric Rating Scale (p < 0.02) and negatively correlated with scores on the Global Assessment Scale (p < 0.005). During the first month of treatment, the reduction of FT3 and FT4 levels was significantly correlated with a decrease in psychiatric symptoms. By 6 months, the FT3 level was no longer significantly different from that at the baseline, but FT4 levels remained significantly lower. The TSH level increased progressively from baseline to 6 months. Multilevel models showed that FT4 and serum lithium levels were positively and negatively associated with psychiatric symptoms, respectively. The findings of the study lend support to the notion that euthyroid hyperthyroxinemia contributes to acute mania and suggest that lithium's short-term antimanic action may be mediated by its antithyroid effect.

Mitogenic effect of lithium in FRTL-5 cells can be reversed by blocking de novo cholesterol synthesis and subsequent signal transduction

Lithium therapy is the therapeutic mainstay for bipolar disorder and has been associated in the thyroid with euthymic goiter, hyper and hypothyroidism as well as thyroid autoimmune disease. The FRTL-5 cell line is a well known model of thyroid cell physiology, where lithium has been shown to increase 3H-thymidine uptake at concentrations of 2 mM. This mitogenic effect was not associated with adenylate cyclase as measured by cyclic adenosine monophosphate (cAMP) production. The de novo synthesis of cholesterol is an important signal transduction pathway in FRTL-5 cells, where newly synthesized Rho GTPase is geranylgeranylated, enabling membrane localization of the G-protein and subsequent G1 to S-phase transition, resulting from extracellular stimulation. Here we confirm lithium mitogenicity at therapeutically relevant concentrations (1 mM) and demonstrate a lithium-associated accumulation of FRTL-5 cells in S-phase of the cell cycle. These effects could be abolished by Pravastatin, a potent inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA), the rate-limiting enzyme in the formation of intermediates (de novo cholesterol synthesis) required for G-protein prenylation. Pravastatin, similar to lithium, showed no effect on cAMP production either under basal or thyroid stimulating hormone (TSH)-stimulated conditions indicating that de novo cholesterol synthesis is not involved with adenylate cyclase. The inhibitory effect of pravastatin could be overcome by reinitiating de novo cholesterol synthesis. This was achieved by the addition of the cell permeable, first metabolite (mevalonate) after HMG-CoA, which allowed the cycle to continue, leading eventually to protein prenylation, despite the presence of Pravastatin. These novel findings demonstrate lithium involvement in de novo cholesterol synthesis and G-protein prenylation, an important signal transduction pathway in FRTL-5 cells.

Association between lower serum free T4 and greater mood instability and depression in lithium-maintained bipolar patients

OBJECTIVE

This investigation evaluated the relationship between changes in thyroid indices and mood stability during lithium and carbamazepine prophylaxis for bipolar disorder.

METHOD

In the first 2 years, 30 patients with bipolar mood disorder were randomly assigned to 1 year of lithium and then 1 year of carbamazepine, or vice versa; in the third year, they received lithium plus carbamazepine. By stepwise regression analysis, the degree and timing of lithium- and carbamazepine-induced thyroid changes and their subsequent relationship to long-term mood stability were evaluated.

RESULTS

During the lithium phase, there was a significant inverse relationship between morbidity and mean serum level of free T4, i.e., a lower mean serum level of free T4 was associated with more affective episodes and greater severity of depression as shown by the Beck Depression Inventory. During the carbamazepine phase, there was an inverse relationship between mean level of total T4 and global severity rating. During the combination phase, no relationships between thyroid indices and clinical outcome were significant.

CONCLUSIONS

In the lithium phase, a low level of free T4 was associated with more affective episodes and greater severity of depression. Whether this mood instability is causally related to low free T4 levels and whether it can be attenuated with T4 replacement remain to be studied in a controlled setting.