Autoantibodies are not Predictive Markers for the Development of Depressive Symptoms in a Population-Based Cohort of Older Adults

Association of Levothyroxine Treatment and Thyroid Peroxidase Antibodies with Antidepressant Use: A Danish Population-Based Longitudinal Study

Background: Subjects receiving levothyroxine (LT4) treatment have increased prevalence of depression, anxiety, and antidepressant use, but whether the underlying mechanism relates to thyroid autoimmunity is still unclarified. Methods: This is a population-based longitudinal study. Baseline biochemical and questionnaire data from the Danish General Suburban Population Study (GESUS) in 2010-2013 were linked with individual-level longitudinal data in national health registries. The aim was to investigate the associations between thyroid peroxidase antibodies (TPOAbs) and LT4 treatment, separately and through interaction, and at least one redeemed prescription for antidepressants. Logistic and Cox regression were used to evaluate initiation of antidepressant use before and after the baseline examination in GESUS, respectively. All exposures and covariates were fixed at the date of baseline examination. Thyroid autoimmunity was defined as serum TPOAbs >60 U/mL. Adjustments included sex, age, education, income, Charlson comorbidity index, smoking, and alcohol. Sensitivity analyses were performed for missing variables, exclusion of lithium use, exclusion of thyroid surgery, and conservative definitions for LT4 treatment and antidepressant use requiring at least two prescriptions. Results: We included 12,894 individuals, of whom 2353 (18%) had "past or current" antidepressant use at baseline, leaving 10,541 individuals at risk for incident antidepressant use after baseline. The median follow-up was 7.8 years during which 783 individuals (7.4% of 10,541 individuals) had incident antidepressant use. TPOAb positivity was not associated with "past or current" (odds ratio [OR] 0.90 [confidence interval, CI 0.78-1.03], p = 0.13) nor incident antidepressant use (hazard ratio [HR] 1.02 [CI 0.83-1.25], p = 0.88). LT4 treatment was associated with increased "past or current" antidepressant use (OR 1.33 [CI 1.10-1.62], p = 0.004) and increased incident antidepressant use (HR 1.38 [CI 1.03-1.85], p = 0.03). There were no interactions between the effects of TPOAb positivity and LT4 treatment on the use of antidepressants in logistic (p = 0.87) or Cox regression models (p = 0.82). Sensitivity analyses were robust, except that incident use of at least two redeemed antidepressant prescriptions was not statistically significant. Conclusions: LT4 treatment, but not TPOAb positivity, was associated with increased prevalent or incident antidepressant use with at least one prescription. Our findings do not support that thyroid autoimmunity is an important factor for antidepressant use in patients receiving LT4 treatment.

Association of Subclinical Hypothyroidism With Anxiety Symptom in Young First-Episode and Drug-Naïve Patients With Major Depressive Disorder

BACKGROUNDS

Subclinical hypothyroidism (SCH) was reported to be associated with depression; however, its role in coexisting anxiety symptom in young patients with major depressive disorder (MDD) remains unclear. The objective of this study was to explore the relationship between SCH and anxiety symptom in young first-episode and drug-naïve (FEDN) MDD patients.

METHODS

A total of 520 outpatients diagnosed as FEDN MDD with SCH were recruited in this study. Their socio-demographic, clinical data and thyroid function parameters were collected. The Hamilton Anxiety Rating Scale (HAMA) and the Hamilton Depression Rating Scale (HAMD) were employed to measure the severity of anxiety symptom and depressive symptom, respectively. Based on the HAMA scores, patients who scored ≥ 25 were defined as anxious major depressive disorder (A-MDD) while others as non-anxious major depressive disorder (NA-MDD).

RESULTS

The prevalence rate of A-MDD was 15.8% in young FEDN MDD patients with comorbid SCH. Moreover, serum thyroid stimulating hormone (TSH) levels were significantly higher in patients with A-MDD compared with those with NA-MDD (p < 0.001). Multivariate binary logistic regression analysis indicated that A-MDD was associated with serum TSH levels with an odds ratio (OR) of 1.602. Serum TSH level of 6.17 mIU/L was the critical value to distinguish A-MDD and NA-MDD, with sensitivity of 0.805 and specificity of 0.539. There were no statistically significant differences between NA-MDD and A-MDD patients in terms of socio-demographic variables, serum free triiodothyronine (FT3), free thyroxine (FT4), thyroid peroxidases antibody (TPOAb) and anti-thyroglobulin (TgAb) levels.

CONCLUSIONS

A-MDD patients presented higher serum TSH level. It is suggested that serum TSH level may be a potential biomarker for predicting moderate and severe anxiety symptoms in young FEDN MDD patients with SCH.

Persisting symptoms in patients with Hashimoto's disease despite normal thyroid hormone levels: Does thyroid autoimmunity play a role? A systematic review

OBJECTIVE

Patients with hypothyroidism due to Hashimoto's disease (HD) may experience persisting symptoms despite normal serum thyroid hormone (TH) levels. Several hypotheses have been postulated to explain these persisting symptoms. We hypothesized that thyroid autoimmunity may play a role.

DESIGN

A systematic literature review.

METHODS

A PubMed search was performed to find studies investigating the relation between the presence of thyroid autoimmunity and (persisting) symptoms. Included studies were critically appraised by the Newcastle - Ottawa Scale (NOS) and then subdivided into (A) disease-based studies, comparing biochemically euthyroid patients with HD, and euthyroid patients with non-autoimmune hypothyroidism or euthyroid benign goitre, and (B) (general) population-based studies. Due to different outcome measures among all studies, meta-analysis of data could not be performed.

RESULTS

Thirty out of 1259 articles found in the PubMed search were included in this systematic review. Five out of seven disease-based studies found an association between thyroid autoimmunity and symptoms or lower quality of life (QoL). Sixteen of 23 population-based studies found a comparable positive association. In total, the majority of included studies reported an association between thyroid autoimmunity and persisting symptoms or lower QoL in biochemically euthyroid patients.

CONCLUSION

(Thyroid) autoimmunity seems to be associated with persisting symptoms or lower QoL in biochemically euthyroid HD patients. As outcome measures differed among the included studies, we propose the use of similar outcome measures in future studies. To prove causality, a necessary next step is to design and conduct intervention studies, for example immunomodulation vs. placebo preferably in the form of a randomized controlled trial, with symptoms and QoL as main outcomes.

Individual and stable autoantibody repertoires in healthy individuals

In the era towards precision medicine, we here present the individual specific autoantibody signatures of 193 healthy individuals. The self-reactive IgG signatures are stable over time in a way that each individual profile is recognized in longitudinal sampling. The IgG autoantibody reactivity towards an antigen array comprising 335 protein fragments, representing 204 human proteins with potential relevance to autoimmune disorders, was measured in longitudinal plasma samples from 193 healthy individuals. This analysis resulted in unique autoantibody barcodes for each individual that were maintained over one year's time. The reactivity profiles, or signatures, are person specific in regards to the number of reactivities and antigen specificity. Two independent data sets were consistent in that each healthy individual displayed reactivity towards 0-16 antigens, with a median of six. Subsequently, four selected individuals were profiled on in-house produced high-density protein arrays containing 23,000 protein fragments representing 14,000 unique protein coding genes. Based on a unique, broad and deep longitudinal profiling of autoantibody reactivities, our results demonstrate a unique autoreactive profile in each analyzed healthy individual. The need and interest for broad-ranged and high-resolution molecular profiling of healthy individuals is rising. We have here generated and assessed an initial perspective on the global distribution of the self-reactive IgG repertoire in healthy individuals, by investigating 193 well-characterized healthy individuals. Highlights A unique longitudinal profiling of autoantibody repertoires in healthy individuals Autoantibody profiles are highly individual and stable over time All individuals display IgG binding to human protein fragments The specificity of disease associated autoantigens needs to be thoroughly characterized The identification of a small set of highly reactive autoantigens Importance of stringent antigen and sample specific cut-offs for defining reactivity.