Hyperthyroidism and Risk for Bipolar Disorders: A Nationwide Population-Based Study

Background

Thyroid disorders have long been associated with psychiatric illness, often with symptoms suggestive of mood disorders. The most common clinical features associated with hyperthyroidism are anxiety and depression. The risk of bipolar disorders, especially bipolar mania, among patients with thyroid disorders has not been well characterized.

Objective

We explored the relationship of hyperthyroidism and the subsequent development of bipolar disorders, and examined the risk factors for bipolar disorders in patients with hyperthyroidism.

Methods

We identified patients who were diagnosed with hyperthyroidism between 2000 and 2010 in the Taiwan National Health Insurance Research Database. A comparison cohort without hyperthyroidism was matched based on age, sex, and comorbidities. The occurrence of bipolar disorders was evaluated in both cohorts based on diagnosis and the use of mood stabilizer drugs.

Results

The hyperthyroidism cohort consisted of 21, 574 patients, and the comparison cohort consisted of 21, 574 matched control patients without hyperthyroidism. The incidence of bipolar disorders (incidence rate ratio [IRR], 2.31, 95% CI 1.80–2.99, P<.001) was higher for the hyperthyroidism patients than the control patients. Multivariate, matched regression models showed that women (HR 2.02, 95% CI 1.34–3.05, P = .001), patients with alcohol use disorders (HR 3.03, 95% CI 1.58–5.79, P = .001), and those with asthma (HR 1.70, 95% CI 1.18–2.43, P = .004) were independent risk factors for the development of bipolar disorders in hyperthyroidism patients.

Conclusions

Although a possibility that the diagnosis of bipolar disorders in this study actually includes "bipolar disorders due to hyperthyroidism" cannot be excluded, this study suggests that hyperthyroidism may increase the risk of developing bipolar disorders.     

Rheumatoid Arthritis and the Risk of Bipolar Disorder: A Nationwide Population-Based Study

Background

Studies have suggested that chronic inflammation plays an essential role in the pathophysiology of both rheumatoid arthritis (RA) and bipolar disorder. The most common clinical features associated with RA are anxiety and depression. The risk of bipolar disorder among patients with RA has not been characterized adequately.

Objective

To determine the association between RA and the subsequent development of bipolar disorder and examine the risk factors for bipolar disorder among patients with RA.

Methods

We identified patients who were diagnosed with RA in the Taiwan National Health Insurance Research Database. A comparison cohort was created by matching patients without RA with those with RA according to age, sex, and comorbidities. The occurrence of bipolar disorder was evaluated in both cohorts.

Results

The RA cohort consisted of 2,570 patients, and the comparison cohort consisted of 2,570 matched control patients without RA. The incidence of bipolar disorder (incidence rate ratio  = 2.13, 95% confidence interval [CI]  = 1.12–4.24, P =  .013) was higher among patients with RA than among control patients. Multivariate, matched regression models revealed that asthma (hazard ratio [HR]  = 2.76, 95% CI 1.27–5.96, P =  .010), liver cirrhosis (HR  = 3.81, 95% CI  = 1.04–14.02, P =  .044), and alcohol use disorders (HR  = 5.29, 95% CI  = 1.71–16.37, P =  .004) were independent risk factors for the development of bipolar disorder among patients with RA.

Conclusion

RA might increase the incidence of bipolar disorder development. Based on our data, we suggest that, following RA diagnosis, greater attention be focused on women with asthma, liver cirrhosis, and alcohol use disorder. Prospective clinical studies of the relationship between RA and bipolar disorder are warranted.     

Risk of Psychiatric Disorders following Polycystic Ovary Syndrome: A Nationwide Population-Based Cohort Study

Background

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders among women of reproductive age. A higher prevalence of psychiatric comorbidities, including depressive disorder, anxiety disorder, and bipolar disorder has been proved in patients with PCOS. However, a clear temporal causal relationship between PCOS and psychiatric disorders has not been well established.

Objective

We explored the relationship between PCOS and the subsequent development of psychiatric disorders including schizophrenia, bipolar disorder, depressive disorder, anxiety disorder, and sleep disorder.

Methods

We identified patients who were diagnosed with PCOS by an obstetrician-gynecologist in the Taiwan National Health Insurance Research Database. A comparison cohort was constructed of patients without PCOS who were matched according to age and sex. The occurrence of subsequent new-onset psychiatric disorders was evaluated in both cohorts based on diagnoses made by psychiatrists.

Results

The PCOS cohort consisted of 5431 patients, and the comparison cohort consisted of 21,724 matched control patients without PCOS. The incidence of depressive disorder (hazard ratio [HR] 1.296, 95% confidence interval [CI] 1.084–.550), anxiety disorder (HR 1.392, 95% CI 1.121–1.729), and sleep disorder (HR 1.495, 95% CI 1.176–1.899) were higher among the PCOS patients than among the patients in the comparison cohort. In addition, a higher incidence of newly diagnosed depressive disorder, anxiety disorder, and sleep disorder remained significantly increased in all of the stratified follow-up durations (0–1, 1–5, ≥5 y).

Conclusions

PCOS might increase the risk of subsequent newly diagnosed depressive disorder, anxiety disorder, and sleep disorder. The risk of newly diagnosed bipolar disorder, which has often been reported in the literature to be comorbid with PCOS, was not significantly elevated.     

Irritable Brain Caused by Irritable Bowel? A Nationwide Analysis for Irritable Bowel Syndrome and Risk of Bipolar Disorder

Objective

We explored the association between IBS and the development of bipolar disorder, and the risk factors for bipolar disorders in patients with IBS.

Methods

We identified patients who were newly diagnosed with IBS between 2000 and 2010 in the Taiwan National Health Insurance Research Database. We also identified a comparison matched cohort without IBS. The occurrence of new-onset bipolar disorder was evaluated in both cohorts.

Results

The IBS cohort consisted of 30,796 patients and the comparison cohort consisted of 30,796 matched patients without IBS. The incidence of bipolar disorder (incidence rate ratio, 2.63, 95% confidence interval (CI) 2.10–3.31, P < .001) was higher in the IBS patients than in the matched cohort. Multivariate matched regression models indicated that autoimmune diseases (HR 1.52, 95% CI 1.07–2.17, P = .020), and asthma (HR 1.45, 95% CI 1.08–1.95, P = .013) were independent risk factors for the development of bipolar disorder in the IBS patients.

Conclusion

IBS may increase the risk of developing subsequent bipolar disorder. Additional prospective studies are required to confirm these findings.     

The Risk of Cancer among Taiwanese Female Registered Nurses: A Nationwide Retrospective Study

Background

To evaluate the risk of cancer among Taiwanese female registered nurses (RNs) using a nationwide population-based dataset.

Methods

We recruited female RNs without antecedent cancer from the Taiwan National Health Insurance Research database during 2000–2010. Standardized incidence ratios (SIRs) of cancer were calculated. We also compared rates of Papanicolaou (Pap) smear use between the RNs and the general population matched by age and sex.

Results

A total of 2,077 cancers developed among 184,809 female RNs, with a follow-up of 1,371,910 person-years (median follow-up of 7.86 years), leading to an increased SIR of 1.10 [95% confidence interval (CI) 1.05–1.15]. RNs aged between 40–59 years also had a significantly increased SIR (1.14, 95% CI 1.08–1.21). For specific cancer types, RNs had an increased SIR for breast (1.28, 95% CI 1.19–1.37), thyroid (1.26, 95% CI 1.10–1.43), lung and mediastinum (1.36, 95% CI 1.13–1.62), and uterine cancers (1.23, 95% CI 1.01–1.49). A decreased SIR was found for cervix (0.48, 95% CI 0.37–0.61) and liver and biliary tract cancers (0.68, 95% CI 0.50–0.90). Pap smear use averaged 5.80 times per person among female RNs aged 35 years or older and 5.50 times per person in the age-matched control group (p = 0.009).

Conclusion

This study found that overall cancer risk was higher among female RNs than general population. For individual cancers, the risks of breast, lung, thyroid and uterine cancer were higher and the risks of cervix and liver cancer were lower than general population. The lower risk of cervical cancer might be partially explained by the increased use of Pap smears in the RNs group. Further large, unbiased population-based prospective studies are needed to investigate the association between nurses and cancer risk and identify the risk factors of cancer in nurses.     

Determination of low molecular weight dicarboxylic acids and organic functional groups in rhizosphere and bulk soils of Tsuga and Yushania in a temperate rain forest

Low molecular weight organic acids (LMWOAs) derived from root exudates, decomposing organic matter, and other sources are important ligands. The species of these LMWOAs in the Tsuga rhizosphere soil (TRS), and Yushania rhizosphere soil (YRS), and bulk soil (BS) from an alpine forest region were identified. LMWOA and organic functional groups were used to those fresh twigs and leaves, litters, and roots as comparison. The objectives of this study were to (i) develop a method that could be used to determine LMWOAs in soil solution by gas chromatography (GC), (ii) assess methods for processing LMWOAs in soil samples, and (iii) determine the relative proportions of organic carbon functional groups in the TRS, YRS and BS, and fresh plant materials with¹³C nuclear magnetic resonance (¹³C NMR) analysis. The proportion of organic acid contents followed the order of YRS > TRS > BS, and also showed significant differences (P < 0.05) from GC analysis. The amounts of malonic, fumaric and succinic acids in the YRS samples were greater than in the TRS and BS. Samples analyzed after 1 month of deep freeze storage (–24°C) showed no signs of decomposition. The proportion of organic functional groups in the rhizosphere and bulk soils quantified by ¹³C NMR analyses followed the general order: alkyl-C > O-alkyl-C > N-alkyl-C > acetal-C > aromatic-C > carboxylic-C > phenolic-C.