Shared genetic architecture highlights the bidirectional association between major depressive disorder and fracture risk

Background

There is limited evidence suggesting that osteoporosis might exacerbate depressive symptoms, while more studies demonstrate that depression negatively affects bone density and increases fracture risk.

Aims

To explore the relationship between major depressive disorder (MDD) and fracture risk.

Methods

We conducted a nested case-control analysis (32 670 patients with fracture and 397 017 individuals without fracture) and a matched cohort analysis (16 496 patients with MDD and 435 492 individuals without MDD) in the same prospective UK Biobank data set. Further, we investigated the shared genetic architecture between MDD and fracture with linkage disequilibrium score regression and the MiXeR statistical tools. We used the conditional/conjunctional false discovery rate approach to identify the specific shared loci. We calculated the weighted genetic risk score for individuals in the UK Biobank and logistic regression was used to confirm the association observed in the prospective study.

Results

We found that MDD was associated with a 14% increase in fracture risk (hazard ratio (HR) 1.14, 95% CI 1.14 to 1.15, p<0.001) in the nested case-control analysis, while fracture was associated with a 72% increase in MDD risk (HR 1.72, 95% CI 1.64 to 1.79, p<0.001) in the matched cohort analysis, suggesting a longitudinal and bidirectional relationship. Further, genetic summary data suggested a genetic overlap between MDD and fracture. Specifically, we identified four shared genomic loci, with the top signal (rs7554101) near SGIP1. The protein encoded by SGIP1 is involved in cannabinoid receptor type 1 signalling. We found that genetically predicted MDD was associated with a higher risk of fracture and vice versa. In addition, we found that the higher expression level of SGIP1 in the spinal cord and muscle was associated with an increased risk of fracture and MDD.

Conclusions

The genetic pleiotropy between MDD and fracture highlights the bidirectional association observed in the epidemiological analysis. The shared genetic components (such as SGIP1) between the diseases suggest that modulating the endocannabinoid system could be a potential therapeutic strategy for both MDD and bone loss.

The impact of selective serotonin reuptake inhibitors on the thyroid function among patients with major depressive disorder: A systematic review and meta-analysis

Selective serotonin reuptake inhibitors (SSRI) have been claimed to negatively affect the thyroid function, albeit the evidence is controversial. We searched for studies that measured parameters of thyroid function (TSH, T4, Free T4, or T3) before and after a course of SSRI treatment in euthyroid patients with major depressive disorder. Electronic searches were conducted on MEDLINE, Embase and Web of Science databases from inception through April 4th, 2018. We performed random-effects meta-analyses to estimate the effect of SSRIs on each hormone. A total 1791 records were identified in the electronic search, and 14 observational clinical studies were included in the analyses. All studies had at least moderate risk of bias and were considered of low quality. A course of SSRI treatment was associated with a decrease in T4 of -6.58 nmol/L (95% Confidence Interval [CI], -12.17 to -.99, p = .005, I²=97%; Cohen's d = .50), a decrease in Free T4 of -.91 pmol/L (95% CI, -1.65 to -.16, p = .017, I²=96%; Cohen's d = .66), and a decrease in T3 of -.10 nmol/L (95% CI, -.18 to -.03, p = .007, I²=96%; Cohen's d = .45), and no effect on TSH (0.06 microIU/L, 95% CI, -.05 to .17, p = .285, I²=98%; Cohen's d = .17). We did not detect publication bias in any of the four meta-analyses. We conclude that there is preliminary evidence that SSRIs slightly decrease thyroid function, but quality of evidence is low. Clinical magnitude of such effect is yet unclear.

Sertraline Versus Placebo in Patients with Major Depressive Disorder Undergoing Hemodialysis: A Randomized, Controlled Feasibility Trial

BACKGROUND AND OBJECTIVES

Depression is common in patients on hemodialysis, but data on the benefits and risks of antidepressants in this setting are limited. We conducted a multicenter, randomized, double-blind, placebo-controlled trial of sertraline over 6 months in patients on hemodialysis with depression to determine study feasibility, safety, and effectiveness.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients on hemodialysis at five United Kingdom renal centers completed the Beck Depression Inventory II. Those scoring ≥16 and not already on treatment for depression were invited to undergo diagnostic interview to confirm major depressive disorder. Eligible patients with major depressive disorder were randomized to receive the study medication-either sertraline or placebo. Outcomes included recruitment and dropout rates, change in the Montgomery-Asberg Depression Rating Scale and Beck Depression Inventory II, and qualitative information to guide design of a large-scale trial.

RESULTS

In total, 709 patients were screened and enrolled between April of 2013 and October of 2014; 231 (32.6%) had Beck Depression Inventory II scores ≥16, and 68 (29%) of these were already receiving treatment for depression. Sixty-three underwent diagnostic interview, 37 were diagnosed with major depressive disorder, and 30 were randomized; 21 completed the trial: eight of 15 on sertraline and 13 of 15 on placebo (P=0.05). Dropouts due to adverse and serious adverse events were greater in the sertraline group. All occurred in the first 3 months. Over 6 months, depression scores improved in both groups. Beck Depression Inventory II score fell from 29.1±8.4 to 17.3±12.4 (P<0.001), and Montgomery-Asberg Depression Rating Scale score fell from 24.5±4.1 to 10.3±5.8 (P<0.001). There were no differences between sertraline and placebo groups.

CONCLUSIONS

Although small, this is the largest randomized trial to date of antidepressant medication in patients on hemodialysis. Our results highlight recruitment issues. No benefit was observed, but trial size and the substantial dropout render consideration of benefit inconclusive. A definitive trial could use shorter follow-up and include depressed patients already taking antidepressants.

Mixed States in Bipolar Disorder: Etiology, Pathogenesis and Treatment

Many bipolar disorder patients exhibit mixed affective states, which portend a generally more severe illness course and treatment resistance. In the previous renditions of Diagnostic and Statistical Manual mixed states were narrowly defined in the context of bipolar I disorder, but with the advent of DSM-5 the term “mixed episode” was dropped and replaced by “mixed features” specifier which could be broadly applied to manic, hypomanic and depressive episodes in both the bipolar spectrum and major depressive disorders. This paradigm shift reflected their significance in the prognosis and overall management of mood disorders, so that the clinicians should thoroughly familiarize themselves with the contemporary notions surrounding these conditions. The purpose of this manuscript is to bring to light the current conceptualizations regarding the etiology, pathogenesis and treatment of mixed states. To achieve this goal, in June 2016 an extensive literature search was undertaken using the PubMed database. Some exploratory terms utilized included “mixed states”, “mixed episodes”, “switching”, “rapid cycling” cross referenced with “bipolar disorder”. Focusing on the most relevant and up to date studies, it was revealed that mixed states result from genetic susceptibility in the circadian and dopamine neurotransmission apparatuses and disturbance in the intricate catecholamine-acetylcholine neurotransmission balance which leads to mood fluctuations. The management of mixed states is challenging with atypical antipsychotics, newer anticonvulsants and electroconvulsive therapy emerging as the foremost treatment options. In conclusion, while progress has been made in the neurobiological understanding of mixed states, the currently available therapeutic modalities have only shown limited effectiveness.

Gender Differences in Depressive Symptom Profile: Results from Nationwide General Population Surveys in Korea

This study investigated gender differences in symptom profiles of major depressive disorder (MDD) in the Korean general population. Data were pooled from the series of nationwide Korean Epidemiologic Catchment Area surveys conducted in 2001, 2006 and 2011, respectively. Of the 18,807 participants, 507 (397 women and 110 men) were diagnosed with MDD within the prior 12 months. In agreement with previous studies, women with MDD appeared to be more vulnerable to experiencing atypical depressive episodes defined as depression with two or more symptoms of fatigue, increased appetite and hypersomnia (P < 0.001). In terms of individual symptoms, female gender was significantly related with higher prevalence of fatigue (P = 0.008), hypersomnia (P = 0.001), noticeable psychomotor retardation (P = 0.029) and suicidal attempts (P = 0.016) with adjustment for birth cohort effect, partner status, and employment status. In the same analysis, men with MDD appeared more vulnerable to decreased libido than women (P = 0.009). This is the first report to demonstrate gender differences in symptomatology of MDD in the general Korean population, and the results are comparable to previous investigations from western societies. Assumingly, the intercultural similarity in female preponderance to atypical depression might reflect the common biological construct underlying the gender difference in mechanism of MDD. In clinical settings, gender differences of MDD should be carefully considered, because these features could be related with treatment response and drug side effects.

Prevalence, work-loss days and quality of life of community dwelling subjects with depressive symptoms

The nationwide prevalence of major depressive disorder in Korea is lower than most countries, despite the high suicide rate. To explain this unexpectedly low prevalence, we examined the functional disability and quality of life in community-dwelling subjects with significant depressive symptoms not diagnosable as depressive disorder. A total of 1,029 subjects, randomly chosen from catchment areas, were interviewed with the Center for Epidemiologic Studies Depression scale, Mini International Neuropsychiatric Interview, WHO Quality of Life scale, and the WHO Disability Assessment Schedule. Those with scores over 21 on the depression scale were interviewed by a psychiatrist for diagnostic confirmation. Among community-dwelling subjects, the 1-month prevalence of major depressive disorder was 2.2%, but the 1-month prevalence of depressive symptoms not diagnosable as depressive disorder was 14.1%. Depressive disorders were the cause of 24.7% of work loss days, while depressive symptoms not diagnosable as depressive disorder were the cause of 17.2% of work loss days. These findings support the dimensional or spectrum approach to depressive disorder in the community and might be the missing link between the apparent low prevalence of depressive disorder and high suicide rate in Korea.