Obesity and obstetric complications are associated with rapid-cycling in Italian patients with bipolar disorder

Effect of prior depression diagnosis on bipolar disorder outcomes: A retrospective cohort study using a medical claims database

BACKGROUND

Bipolar disorder often emerges from depressive episodes and is initially diagnosed as depression. This study aimed to explore the effects of a prior depression diagnosis on outcomes in patients diagnosed with bipolar disorder.

METHODS

This cohort study analyzed data of patients aged 18-64 years who received a new bipolar disorder diagnosis in Japan, using medical claims data from January 2005 to October 2020 provided by JMDC, Inc. The index month was defined as the time of the bipolar diagnosis. The study assessed the incidence of psychiatric hospitalization, all-cause hospitalization, and mortality, stratified by the presence of a preceding depression diagnosis and its duration (≥1 or <1 year). Hazard ratios (HRs) and p-values were estimated using Cox proportional hazards models, adjusted for potential confounders, and supported by log-rank tests.

RESULTS

Of the 5595 patients analyzed, 2460 had a history of depression, with 1049 experiencing it for over a year and 1411 for less than a year. HRs for psychiatric hospitalization, all hospitalizations, and death in patients with a history of depression versus those without were 0.92 (95% CI = 0.78-1.08, p = 0.30), 0.87 (95% CI = 0.78-0.98, p = 0.017), and 0.61 (95% CI = 0.33-1.12, p = 0.11), respectively. In patients with preceding depression ≥1 year versus <1 year, HRs were 0.89 (95% CI = 0.67-1.19, p = 0.43) for psychiatric hospitalization, 0.85 (95% CI = 0.71-1.00, p = 0.052) for all hospitalizations, and 0.25 (95% CI = 0.07-0.89, p = 0.03) for death.

CONCLUSION

A prior history and duration of depression may not elevate psychiatric hospitalization risk after bipolar disorder diagnosis and might even correlate with reduced hospitalization and mortality rates.

Prevalence and outcomes of rapid cycling bipolar disorder: Mixed method systematic meta-review

Rapid-cycling in bipolar disorder (RC-BD) is associated with greater illness morbidity and inferior treatment response but many aspects remain unclear, prompting this systematic review of its definitions, prevalence, and clinical characteristics. We searched multiple literature databases through April 2022 for systematic reviews or meta-analyses on RC-BD and extracted associated definitions, prevalence, risk-factors, and clinical outcomes. We assessed study quality (NIH Quality Assessment Tool) and levels of evidence (Oxford criteria). Of 146 identified reviews, 22 fulfilling selection criteria were included, yielding 30 studies involving 13,698 BD patients, of whom 3777 (27.6% [CI: 26.8-28.3]) were considered RC-BD, as defined in 14 reports by ≥4 recurrences/year within the past 12 months or in any year, without considering responsiveness to treatment. Random-effects meta-analytically pooled one-year prevalence was 22.3% [CI: 14.4-32.9] in 12 reports and lifetime prevalence was 35.5% [27.6-44.3] in 18 heterogenous reports. Meta-regression indicated greater lifetime prevalence of RC-BD among women than men (p=0.003). Association of RC-BD with suicide attempts, and unsatisfactory response to mood-stabilizers was supported by strong evidence (Level 1); associations with childhood maltreatment, mixed-features, female sex, and type-II BD had moderate evidence (Level 2). Other factors: genetic predisposition, metabolic disturbances or hypothyroidism, antidepressant exposure, predominant depressive polarity (Level 3), along with greater illness duration and immune-inflammatory dysfunction (Level 4) require further study. RC-BD was consistently recognized as having high prevalence (22.3%-35.5% of BD cases) and inferior treatment response. Identified associated factors can inform clinical practice. Long-term illness-course, metabolic factors, and optimal treatment require further investigation.

Correlates of long duration of untreated illness (DUI) in patients with bipolar disorder: results of an observational study

BACKGROUND

Despite a high number of studies investigating the correlation between long Duration of Untreated Illness (DUI) and poor course of Bipolar Disorder (BD), the results concerning the impact of DUI on some specific factors, such as suicidality and medical comorbidities, are still inconsistent. This cross-sectional observational study aimed at analyzing potential socio-demographic and clinical correlates of long DUI in a large cohort of real-world, well-characterized BD patients.

METHODS

The socio-demographic and clinical characteristics of 897 patients with BD were collected. The sample was divided for analysis in two groups (short DUI vs long DUI) according to a DUI cutoff of 2 years. Comparisons were performed using χ2 tests for categorical variables and the Kruskal-Wallis test for continuous variables. Logistic regression (LogReg) was used to identify explanatory variables associated with DUI (dependent variable).

RESULTS

Six-hundred and sixty patients (75.5%) presented long DUI (> 2 years) and mean DUI was 15.7 years. The LogReg analysis confirmed the association of long DUI with bipolar II disorder (p: 0.016), lower age at onset (p < 0.001), depressive predominant polarity (p: 0.018), depressive polarity onset (p < 0.001), longer duration of illness (p < 0.001), lifetime suicide attempts (p: 0.045) and current medical comorbidities (p: 0.019).

CONCLUSIONS

The present study confirms the association between long DUI and higher risk of suicide attempts in patients with BD. Moreover, an association between long DUI and higher rates of medical conditions has been found.

Which Clinical and Biochemical Parameters Are Associated with Lifetime Suicide Attempts in Bipolar Disorder?

Introduction: Bipolar Disorder (BD) is a disabling condition with suicidal behavior as one of the most common adverse outcomes. The purpose of the present research is to investigate the relationship between lifetime suicide attempts and the clinical factors/biochemical parameters in a large sample of bipolar patients. Methods: A total of 561 patients, consecutively hospitalized for BD in Milan and Monza (Italy), were recruited. Data about the demographic and clinical variables, as well as the values of blood analyses, were collected. The groups identified according to the presence/absence of lifetime suicide attempts were compared using univariate analyses. Then, three preliminary binary logistic regressions and a final logistic regression model were performed to identify the clinical and biochemical parameters associated with lifetime suicide attempts in BD. Results: Lifetime suicide attempts in BD were predicted by a longer duration of untreated illness (DUI) (p = 0.005), absence of lifetime psychotic symptoms (p = 0.025), presence of poly-substance use disorders (p = 0.033), comorbidity with obesity (p = 0.022), a last mood episode of manic polarity (p = 0.044), and lower bilirubin serum levels (p = 0.002); higher total cholesterol serum levels showed a trend toward statistical significance (p = 0.058). Conclusions: BD patients with lifetime suicide attempts present unfavorable clinical features. Some specific biochemical characteristics of bipolar patients may represent potential markers of suicidal behavior and need to be better investigated to identify new targets of treatment in the framework of personalized medicine. These preliminary findings have to be confirmed by further studies in different clinical settings.

Clinical and psychopathological correlates of duration of untreated illness (DUI) in affective spectrum disorders

Affective disorders represent psychopathological entities lying on a continuum, characterized by high prevalence and functional impairment. A delay in treatment initiation might increase the burden associated with affective spectrum disorders. The present study was aimed at analyzing the correlates of a long duration of untreated illness (DUI) in these conditions. We recruited subjects diagnosed with affective disorders, both in- and outpatients, and collected information concerning socio-demographic, clinical, and psychopathological characteristics. Long DUI was defined according to previous research criteria as >2 years for Bipolar Disorders or >1 year for Depressive Disorders. Bivariate analyses were performed to compare subjects with a long and short DUI (p<0.05). A logistic regression was operated to evaluate the correlates of long DUI. In the present sample (n=135), 34.1% (n=46) subjects showed a long DUI. This subgroup presented with more physical comorbidities (p=0.003), higher body mass index (BMI) (p<0.001), more frequent anxiety onset (p=0.018), younger onset age (p=0.042), and more severe depressive symptoms (Hamilton Depression Rating Scale item 1-depressed mood (p=0.032) and item 2-guilt feelings (p=0.018)). At the logistic regression, higher severity of depressed mood (OR 1.568), higher BMI (OR 1.264), and younger age at onset (OR 0.935) were associated with long DUI. The present study confirmed a possible role of DUI as a construct underpinning higher clinical severity in affective spectrum disorders, possibly linked to worse illness course and unfavorable outcomes. Intervention strategies targeting physical comorbidities and depressive symptoms severity may decrease disease burden in subjects with a long DUI.

Factors associated with lifetime suicide attempts in bipolar disorder: results from an Italian nationwide study

The purpose of the present study was to detect demographic and clinical factors associated with lifetime suicide attempts in Bipolar Disorder (BD). A total of 1673 bipolar patients from different psychiatric departments were compared according to the lifetime presence of suicide attempts on demographic/clinical variables. Owing to the large number of variables statistically related to the dependent variable (presence of suicide attempts) at the univariate analyses, preliminary multiple logistic regression analyses were realized. A final multivariable logistic regression was then performed, considering the presence of lifetime suicide attempts as the dependent variable and statistically significant demographic/clinical characteristics as independent variables. The final multivariable logistic regression analysis showed that an earlier age at first contact with psychiatric services (odds ratio [OR] = 0.97, p < 0.01), the presence of psychotic symptoms (OR = 1.56, p < 0.01) or hospitalizations (OR = 1.73, p < 0.01) in the last year, the attribution of symptoms to a psychiatric disorder (no versus yes: OR = 0.71, partly versus yes OR = 0.60, p < 0.01), and the administration of psychoeducation in the last year (OR = 1.49, p < 0.01) were all factors associated with lifetime suicide attempts in patients affected by BD. In addition, female patients resulted to have an increased association with life-long suicidal behavior compared to males (OR: 1.02, p < 0.01). Several clinical factors showed complex associations with lifetime suicide attempts in bipolar patients. These patients, therefore, require strict clinical monitoring for their predisposition to a less symptom stabilization. Future research will have to investigate the best management strategies to improve the prognosis of bipolar subjects presenting suicidal behavior.

Does metabolic syndrome or its component factors alter the course of bipolar disorder? A systematic review

Metabolic syndrome (MetS) and its component factors, obesity, hypertension, dyslipidaemia and insulin resistance, have shown a bidirectional relationship with the prevalence and severity of bipolar disorder (BD). A systematic search of electronic databases (Pubmed, PsycINFO, clinicaltrials.gov) was conducted to explore and integrate current evidence about the role of MetS and its component factors with clinical outcomes of BD. Thirty-four articles met the inclusion criteria. Studies were grouped by the metabolic factors assessed, which included MetS, obesity and body mass index (BMI), dyslipidaemia, impaired glucose metabolism (IGM), diabetes mellitus and hypertension. They were then classified according to outcomes such as course of episodes, rapid cycling, suicidal behavior, treatment response, and global and cognitive functioning. Although current evidence remains controversial in most aspects of clinical outcomes, metabolic risk factors could alter the course of BD, with worse global functioning, poorer treatment response and a chronic course of illness, as well as enhancing rapid cycling. Further research is needed to elucidate the role of each risk factor in the mentioned outcomes.

Which factors delay treatment in bipolar disorder? A nationwide study focussed on duration of untreated illness

AIM

The aim of the present study was to detect factors associated with duration of untreated illness (DUI) in bipolar disorder (BD).

METHOD

A total of 1575 patients were selected for the purposes of the study. Correlation analyses were performed to analyse the relation between DUI and quantitative variables. The length of DUI was compared between groups defined by qualitative variables through one-way analyses of variance or Kruskal-Wallis's tests according to the distribution of the variable. Linear multivariable regressions were used to find the most parsimonious set of variables independently associated with DUI: to this aim, qualitative variables were inserted with the numeric code of their classes by assuming a proportional effect moving from one class to another.

RESULTS

An inverse significant correlation between length of DUI and time between visits in euthymic patients was observed (r = -.52, P < .001). DUI resulted to be longer in patients with: at least one lifetime marriage/partnership (P = .009), a first psychiatric diagnosis of major depressive disorder or substance abuse (P < .001), a depressive polarity of first episode (P < .001), no lifetime psychotic symptoms (P < .001), BD type 2 (P < .001), more lifetime depressive/hypomanic episodes (P < .001), less lifetime manic episodes (P < .001), presence of suicide attempts (P = .004), depressive episodes (P < .001), hypomanic episodes (P = .004), hospitalizations (P = .011) in the last year.

CONCLUSIONS

Different factors resulted to increase the length of DUI in a nationwide sample of bipolar patients. In addition, the DUI was found to show a negative long-term effect in terms of more suicidal behaviour, more probability of hospitalization and depressive/hypomanic episodes.

A miRNome analysis of drug-free manic psychotic bipolar patients versus healthy controls

The lifetime presence of psychotic symptoms is associated with more clinical severity, poorer outcome and biological changes in patients affected by bipolar disorder (BD). Epigenetic mechanisms have been evoked to explain the onset of psychotic symptoms in BD as well as the associated biological changes. The main objective of the present study was to evaluate the expression profiles of circulating microRNAs (miRNAs) in drug-free manic psychotic bipolar patients versus healthy controls (HC), to identify possible non-invasive molecular markers of the disorder. 15 drug-free manic psychotic bipolar patients and 9 HC were enrolled and 800 miRNAs expression profile was measured by Nanostring nCounter technology on plasma samples and validated through qPCR. Overall, twelve miRNAs showed a significantly altered expression between the two groups (p < 0.05). Functional annotation of predicted miRNAs targets by MultiMIR R tool showed repression in bipolar patients of genes with a role in neurodevelopment and neurogenesis, and upregulation of genes involved in metabolism regulation. We identified a signature of circulating miRNA characteristic of manic psychotic bipolar patients, suggesting a possible role in neurodevelopment and metabolic processes regulation.

Gender-related differences in patients with bipolar disorder: a nationwide study

OBJECTIVE

The possible presence of gender-related differences in patients with bipolar disorder (BD) may have diagnostic and therapeutic implications. This multicenter study aimed to investigate gender differences in BD in the largest Italian database collected to date, on behalf of the Italian Chapter of the International Society of Bipolar Disorders.

METHODS

A total of 1674 patients (males: n = 714; females: n = 960) from different psychiatric departments were compared according to gender on demographic/clinical variables. Owing to the large number of variables statistically related to the dependent variable (gender) at the univariate analyses, preliminary multiple logistic regression analyses were performed. A final multivariable logistic regression was then performed, considering gender as the dependent variable and statistically significant demographic/clinical characteristics as independent variables.

RESULTS

The results of the final multivariable logistic regression analysis with previous statistically significant demographic and clinical variables were the following: female gender was less frequently associated with employment (odds ratio [OR] = 0.7, P < 0.01), lifetime single marital status (OR = 0.45, P < 0.01), and substance abuse in the last year (OR = 0.35, P < 0.01), whereas it was more frequently associated with a major number of lifetime major depressive episodes (OR = 1.78, P < 0.01) and psychiatric visits in the last year (OR = 1.38, P = 0.01).

CONCLUSION

Few significant differences were found between genders in BD, particularly for those clinical features that are associated with poor prognosis (substance abuse for males and number of depressive episodes for females). Transcultural studies are needed to identify cultural versus illness-related variables possibly explaining the different clinical presentation of BD in relation to gender.

Correlates of current rapid-cycling bipolar disorder: Results from the Italian multicentric RENDiBi study

BACKGROUND

we aimed to compare socio-demographic and clinical differences between patients with versus without current RC in order to detect clinical factors that may favor early diagnosis and personalized treatment.

METHODS

A total of 1675 patients (males: n = 714 and females: n = 961; bipolar 1: n = 1042 and bipolar 2: n = 633) from different psychiatric clinics were grouped and compared according to the current presence of RC in terms of socio-demographic and clinical variables. Chi-squared tests for qualitative variables and Student's t tests for quantitative variables were executed for group comparison, and multivariable logistic regressions were performed, considering the current presence of RC as dependent variable, and socio-demographic/clinical factors as independent variables.

RESULTS

Female gender (male versus female: OR = 0.64, p = 0.04), unidentifiable prevalent polarity (versus depressive polarity: OR = 1.76, p = 0.02; versus manic polarity: OR: 2.86, p < 0.01) and hospitalization in the last year (no versus yes: OR = 0.63, p = 0.02) were found to be associated with RC in the final multivariable regression analysis.

CONCLUSIONS

RC in BD seems to be more prevalent in female gender and associated with some unfavorable clinical features, such as an increased risk of hospitalization. These aspects should be taken into account in the management and monitoring of RC versus non-RC patients.

Psychotic versus non-psychotic bipolar disorder: Socio-demographic and clinical profiles in an Italian nationwide study

OBJECTIVE

Psychotic versus non-psychotic patients with bipolar disorder have been traditionally associated with different unfavorable clinical features. In this study on bipolar Italian patients, we aimed to compare clinical and demographic differences between psychotic and non-psychotic individuals, exploring clinical factors that may favor early diagnosis and personalized treatment.

METHODS

A total of 1671 patients (males: n = 712 and females: n = 959; bipolar type 1: n = 1038 and bipolar type 2: n = 633) from different psychiatric departments were compared according to the lifetime presence of psychotic symptoms in terms of socio-demographic and clinical variables. Chi-square tests for qualitative variables and Student's t-tests for quantitative variables were performed for group comparison, and a multivariable logistic regression was performed, considering the lifetime psychotic symptoms as dependent variables and socio-demographic/clinical characteristics as independent variables.

RESULTS

Psychotic versus non-psychotic bipolar subjects resulted to: be more frequently unemployed (p < 0.01) and never married/partnered (p < 0.01); have an earlier age at onset (p < 0.01); more frequently receive a first diagnosis different from a mood disorder (p < 0.01); have a shorter duration of untreated illness (p < 0.01); have a more frequently hypomanic/manic prevalent polarity (p < 0.01) and a prevalent manic-depressive type of cycling (p < 0.01); present a lower lifetime number of depressive episodes (p < 0.01), but have more manic episodes (p < 0.01); and less insight (p < 0.01) and more hospitalizations in the last year (p < 0.01). Multivariable regression analysis showed that psychotic versus non-psychotic bipolar patients received more frequently a first diagnosis different from bipolar disorder (odds ratio = 0.64, 95% confidence interval = [0.46, 0.90], p = 0.02) or major depressive disorder (odds ratio = 0.66, 95% confidence interval = [0.48, 0.91], p = 0.02), had more frequently a prevalent manic polarity (odds ratio = 1.84, 95% confidence interval = [1.14, 2.98], p < 0.01) and had a higher number of lifetime manic episodes (more than six) (odds ratio = 8.79, 95% confidence interval = [5.93, 13.05], p < 0.01).

CONCLUSION

Lifetime psychotic symptoms in bipolar disorder are associated with unfavorable socio-demographic and clinical features as well as with a more frequent initial misdiagnosis.

Differential Impact of Obesity on CD69 Expression in Individuals with Bipolar Disorder and Healthy Controls

Preliminary evidence suggests that premature immunosenescence is involved in bipolar disorder (BD) pathophysiology. The cellular marker CD69 is expressed in T lymphocyte surface during their activation and its expression is negatively correlated with age. The objective of this study was to assess the moderating effects of obesity on the reduction of expression of CD69, a marker of immunosenescence. Forty euthymic patients with BD type I, aged 18-65 years, were included in this study. The healthy comparison group consisted of 39 volunteers who had no current or lifetime history of mental disorders, no use of psychotropic medications, and no known family history of mood disorders or psychosis. Peripheral blood mononuclear cells from BD patients and healthy controls were collected and isolated. The cells were allowed to grow in culture and stimulated for 3 days. CD69 was marked and read in flow cytometry. We found that the lower expression of CD69 in BD patients was moderated by body mass index (BMI) in both CD4+ (RR = 0.977, 95% CI 0.960-0.995, p = 0.013) and CD8+ cells (RR = 0.972, 95% CI 0.954-0.990, p = 0.003). Our findings indicate that BMI could potentially influence the process of premature aging in BD.

Biological aspects and candidate biomarkers for rapid-cycling in bipolar disorder: A systematic review

Rapid-cycling bipolar disorder represents a frequent severe subtype of illness which has been associated with poor response to pharmacological treatment. Aim of the present article is to provide an updated review of biological markers associated with rapid-cycling bipolar disorder. A research in the main database sources has been conducted to identify relevant papers about the topic. Rapid-cycling bipolar disorder patients seem to have a more frequent family history for bipolar spectrum disorders (d range: 0.44-0.74) as well as an increased susceptibility to DNA damage or mRNA hypo-transcription (d range: 0.78-1.67) than non rapid-cycling ones. A susceptibility to hypothyroidism, which is exacerbated by treatment with lithium, is possible in rapid-cycling bipolar disorder, but further studies are needed to draw definitive conclusions. Rapid-cycling bipolar patients might have more insuline resistance as well as more severe brain changes in frontal areas (d range: 0.82-0.94) than non rapid-cycling ones. Many questions are still open about this topic. The first is whether the rapid-cycling is inheritable or is more generally the manifestation of a severe form of bipolar disorder. The second is whether some endocrine dysfunctions (diabetes and hypothyroidism) predispose to rapid-cycling or rapid-cycling is the consequence of drug treatment or medical comorbidities (e.g. obesity).

Quetiapine-Induced Hypomania and its Association with Quetiapine/Norquetiapine Plasma Concentrations: A Case Series of Bipolar Type 2 Patients

International guidelines consider quetiapine at medium doses (300-400 mg/day) as valid options for the treatment of bipolar depression for the supposed lower risk of a switch to hypomania/mania than antidepressants. Norquetiapine is an active metabolite with antidepressant action. We describe three cases of induced hypomania in bipolar type 2 subjects who received quetiapine extended-release monotherapy (300 mg/day) for a mild/moderate major depressive episode. Quetiapine and norquetiapine plasma concentrations were measured after 1 week of treatment. Hypomania appeared after 7-10 days of quetiapine extended-release monotherapy and all subjects had a quetiapine/norquetiapine plasma concentration ratio <1. We propose a ratio value <1 as a predictor of risk for a switch to hypomania in bipolar depressed subjects receiving quetiapine extended-release monotherapy. Future research should ascertain the validity of this laboratory parameter to assess the risk of quetiapine-induced hypomania in large samples of bipolar patients.

Infectious and immunogenetic factors in bipolar disorder

OBJECTIVE

Despite the evidence supporting the association between infection and bipolar disorder (BD), the genetic vulnerability that mediates its effects has yet to be clarified. A genetic origin for the immune imbalance observed in BD, possibly involved in the mechanisms of pathogen escape, has, however, been suggested in recent studies.

METHOD

Here, we present a critical review based on a systematic literature search of articles published until December 2016 on the association between BD and infectious/immunogenetic factors.

RESULTS

We provide evidence suggesting that infectious insults could act as triggers of maladaptive immune responses in BD and that immunogenetic vulnerability may amplify the effects of such environmental risk factors, increasing susceptibility to subsequent environmental encounters. Quality of evidence was generally impaired by scarce attempt of replication, small sample sizes and lack of high-quality environmental measures.

CONCLUSION

Infection has emerged as a potential preventable cause of morbidity in BD, urging the need to better investigate components of the host-pathogen interaction in patients and at-risk subjects, and thus opening the way to novel therapeutic opportunities.

Quetiapine monotherapy versus placebo in the treatment of children and adolescents with bipolar depression: a systematic review and meta-analysis

BACKGROUND

Some studies have indicated the efficacy of quetiapine in the treatment of bipolar depression in adult patients. However, its efficacy has been not shown in child and adolescent patients.

OBJECTIVE

This systematic review purposefully determined the efficacy and acceptability of quetiapine in the treatment of children and adolescents with bipolar depression.

DATA SOURCES

A database search of EMBASE, PubMed, CINAHL, and Cochrane Controlled Trials Register was carried out in March 2016. All randomized controlled trials (RCTs) of bipolar depression in children and adolescents were considered for inclusion in this review.

STUDY ELIGIBILITY CRITERIA PARTICIPANTS AND INTERVENTIONS

RCTs of quetiapine in the treatment of child and adolescent patients with bipolar depression with end point outcomes were included in this study. Languages were not limited.

STUDY APPRAISAL AND SYNTHESIS METHODS

The full-text versions of relevant clinical studies were thoroughly examined and extracted. The primary efficacy of outcome was measured by using the pooled mean-changed scores of the rating scales for bipolar depression. However, the response and remission rates were also measured.

RESULTS

A total of 251 randomized patients in the three RCTs of quetiapine versus placebo in the treatment of bipolar depression for children and adolescents were eligible in this review. The pooled mean-changed score of the quetiapine-treated group was not greater than that of the placebo-treated group. Similarly, the pooled response and remission rates were not different between the two groups. The pooled overall discontinuation rate and the discontinuation rate due to adverse events were not different between the two groups.

LIMITATIONS

Limited studies were eligible in this review.

CONCLUSION

According to the findings in this review, quetiapine may not be efficacious in the treatment of bipolar depression in children and adolescents. Its acceptability, however, was comparable to a placebo. Therefore, the use of quetiapine in children and adolescents with bipolar depression is not recommended. Further well-defined clinical studies should be performed to confirm these outcomes.