Persistent increase over time in oxidatively stress generated RNA and DNA damage in patients with newly diagnosed bipolar disorder and their unaffected first-degree relatives - An up to 5-year prospective study

Investigation of malondialdehyde as a trait marker associated with familial risk in patients with newly diagnosed bipolar disorder and their unaffected first-degree relatives - A longitudinal cohort study

AIMS

Increased oxidative stress-generated tissue damage seems to play a pivotal role in the pathophysiology and progression of bipolar disorder (BD). Malondialdehyde (MDA), a product of lipid oxidation, may represent a trait marker in BD associated with familial risk. However, MDA is scarcely studied in patients with newly diagnosed bipolar disorder (BD) and their unaffected relatives (UR).

METHODS

In this prospective "the Bipolar Illness Onset study", we investigated repeated measurements of MDA in a cohort of 371 patients with newly diagnosed/first-episode BD (1016 visits), 139 of their unaffected first-degree relatives (307 visits) and 199 healthy control individuals (HC) with no personal or first-degree family history of affective disorder (537 visits) with a median follow-up time of 2.0. [0.1; 3.8] years for patients with BD, 1.4 [0; 2.4] years for UR, and 2.5 [1.1; 3.9] years for HC. Amongst patients with BD, we further investigated associations of MDA with affective phases and medicine- and illness variables over a period of 7 years.

RESULTS

Unaffected relatives had 42.3 % higher levels of MDA at baseline compared with HC in analyses adjusted for sex and age corrected for multiple comparisons (B = = 1.423, 95 % CI = 1.139, 1.777, p = <0.044). However, this difference did not persist over time. No statistically significant differences in MDA levels were observed over time between BD patients and either HC or UR. Additionally, MDA levels were not associated with psychotropic use, illness variables, or affective phase alterations.

CONCLUSIONS

Against expectations, our findings did not support increased lipid oxidation being a trait phenomenon in BD.

The relationship between neuropsychiatric disorders and aging: A review on telomere length, oxidative stress, and inflammation

Aging is the group of time-independent changes that occur in an organism and that ultimately end in death. The relationship between aging and neuropsychiatric disorders is complex. Not only does the incidence of several neuropsychiatric disorders rise with age, but also these disorders are linked with premature mortality and are even thought to be syndromes of accelerated biological aging. Oxidative stress, inflammation and telomere length are factors commonly used to assess biological aging. The purpose of this review is to sum up the existing information about the state of those factors in schizophrenia, depression, bipolar disorder and anxiety disorders, and to summarize the effects of treatment on telomere length in patients with those neuropsychiatric disorders. The main focus, however, is on telomere length seeing the highly controversial study results on this biomarker in neuropsychiatric disorders. There is no scientific consensus on the state of those factors in the mentioned neuropsychiatric disorders or on the effects of treatment on telomere length, thus further research is needed where confounding variables are controlled. Regarding telomere length, it is highly important to explore whether short telomeres lead to the development of neuropsychiatric disorders or vice versa, as it carries huge clinical potential.

Association of lipid-modifying medication with reduced mortality in bipolar disorder: A nationwide cohort study

OBJECTIVE

Patients with bipolar disorder face higher mortality risks from natural causes and suicide. Lipid-modifying medications, among the most widely prescribed medications, also show potential in alleviating mood symptoms. Limited research explores if these medications reduce all-cause, natural, and suicide mortality risks.

METHODS

This national cohort study, using Taiwan's National Health Insurance Research Database (2001-2022), included 32,479 bipolar disorder patients. Among them, 6800 died (4963 natural causes, 1154 suicide). Standardized Mortality Ratios (SMRs) were calculated, and Hazard Ratios (HRs) for lipid-modifying medications were estimated using multivariable Cox proportional hazards regression with a time-dependent model.

RESULTS

SMRs for all-cause, natural, and suicide mortality in the bipolar cohort were 6.36, 5.28, and 29.07, respectively. Lipid-modifying medications were associated with significantly reduced risks of all-cause (aHR = 0.38, P < .001), natural (aHR = 0.41, P < .001), and suicide mortality (aHR = 0.41, P < .001) within the 5-year follow-up post-index admission. Among the differing classes of lipid-modifying medications, statins and fibrates were linked to lower risks of all-cause (statins: aHR = 0.42, P < .001; fibrates: aHR = 0.49, P < .001), natural mortality (statins: aHR = 0.42, P < .001; fibrates: aHR = 0.59, P = .003), and suicide mortality (statins: aHR = 0.51, P = .002; fibrates: aHR = 0.33, P = .006).

CONCLUSIONS

Besides protecting against natural mortality, lipid-modifying medications exhibit salutary associations with suicide and all-cause mortality in bipolar disorder patients. To meaningfully reduce the high mortality rate, future studies should explore the pleiotropic benefits of these medications.

SUMMARY

Lipid-modifying medications are widely recommended to treat cardiometabolic diseases and can have therapeutic potentials to improve mood symptoms associated with bipolar disorder. However, few studies have evaluated whether lipid-modifying medications are associated with a decreased risk of mortality from either natural causes or suicide among patients with bipolar disorder. This study found that in addition to having protective effects against natural mortality, lipid-modifying medications exert protective effects against suicide and all-cause mortality among patients with bipolar disorder.

Lipid oxidation in young patients with newly diagnosed bipolar disorder and their relatives

BACKGROUND

Oxidative stress may be involved in the pathophysiology of bipolar disorder (BD). Malondialdehyde (MDA), a product of fatty acid peroxidation has been proposed as a trait marker of BD associated with familial risk. However, little is known about MDA levels in young patients newly diagnosed with BD and their unaffected first-degree relatives (UR).

METHODS

In this substudy of the ongoing longitudinal "Bipolar Illness Onset study", we included baseline data and first, we compared fasting blood MDA levels in 130 young patients aged 15-25 years newly diagnosed with BD, 57 UR, and 88 healthy control individuals (HC). Second, we investigated associations between levels of MDA and illness variables in patients with BD. Third, we investigated associations between MDA levels and nucleoside damage by oxidation measured in urine. Fasting MDA levels from blood samples were measured using high-performance liquid chromatography (HPLC).

RESULTS

In linear mixed effect models, adjusted for age and sex, MDA levels did not differ between patients with BD, UR, and HC, respectively. In patients with BD, we found no associations between levels of MDA and duration of illness, number of affective phases, illness onset or oxidatively damaged RNA and DNA.

CONCLUSION

Against expectations, MDA levels did not differ between young patients with BD, UR, and HC, thus, our findings did not support MDA being a state or a trait marker of BD associated with familial risk.

Evaluating Oxidative Stress Markers in At-Risk Individuals for Bipolar Disorder: A Systematic Review and Meta-Analysis

INTRODUCTION

Bipolar disorder (BD), a mood disorder with recurrent affective episodes and a strong genetic basis is frequently associated with significant comorbidities, both physical and psychiatric, yet its neurobiology remains unclear. Recent evidence underscores oxidative stress as a pivotal factor linking BD to its comorbidities, prompting an investigation into whether this is a sign of a genetic vulnerability or a consequence of the disease. In this study, we systematically reviewed oxidative stress studies conducted on individuals at risk for BD. We performed a meta-analysis on studies examining oxidative DNA damage in these individuals.

METHODS

The literature was searched across the databases PubMed, Web of Science, Scopus, Ovid MEDLINE, and Cochrane to locate studies of oxidative stress markers in relatives of patients with BD compared with healthy controls (from 1946 to March 2024). Studies were considered for inclusion based on the following criteria: (i) involvement of first- or second-degree relatives of individuals diagnosed with BD, (ii) presence of a healthy control group, (iii) reporting of oxidative stress parameters for relatives, including mean and standard deviation or median and interquartile range (25-75%) values, and (iv) publication in the English language. Studies comparing the levels of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) or its tautomer 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) in individuals at risk for BD with healthy controls were evaluated using a meta-analysis with the random-effects method. The risk of bias was evaluated using the Risk of Bias in Non-Randomized Studies of Exposure (ROBINS-E) tool.

RESULTS

Eleven studies were included in the systematic review and four studies for the meta-analysis. The meta-analysis included 543 individuals (first-degree relatives of individuals with BD = 238, control = 305). 8-OH-dG levels were found to be increased in first-degree relatives of individuals with BD compared to healthy controls (random effects: Hedges's g = 0.53, 95% CI = 0.36-0.71, p < 0.001). Findings of oxidative stress markers other than oxidative DNA damage in relatives of individuals with BD are limited and scarce.

CONCLUSION

In this meta-analysis, which consists of a limited number of studies, oxidative DNA damage seems to be a trait marker for BD. This finding could be associated with increased comorbidity and a higher risk of premature aging in individuals at risk for BD. However, further studies with larger sample sizes and longitudinal designs are warranted to confirm findings. Clarifying the changes in these markers from individuals at risk for the disorder throughout the course of the illness would help bridge the gap in understanding the role of oxidative pathways in the risk of BD.

Lithium response in bipolar disorder: Epigenome-wide DNA methylation signatures and epigenetic aging

Lithium (Li) is the first-line treatment for bipolar disorder (BD) even though only 30 % of BD patients are considered excellent responders. The mechanisms by which Li exerts its action are not clearly understood, but it has been suggested that specific epigenetic mechanisms, such as methylation processes, may play a role. In this regard, DNA methylation patterns can be used to estimate epigenetic age (EpiAge), which is accelerated in BD patients and reversed by Li treatment. Our first aim was to compare the DNA methylation profile in peripheral blood between BD patients categorized as excellent responders to Li (Ex-Rp) and non-responders (N-Rp). Secondly, EpiAge was estimated to detect differential age acceleration between the two groups. A total of 130 differentially methylated positions (DMPs) and 16 differentially methylated regions (DMRs) between Ex-Rp (n = 26) and N-Rp (n = 37) were identified (FDR adjusted p-value < 0.05). We found 122 genes mapping the DMPs and DMRs, nine of which (HOXB6, HOXB3, HOXB-AS3, TENM2, CACNA1B, ANK3, EEF2K, CYP1A1, and SORCS2) had previously been linked to Li response. We found genes related to the GSK3β pathway to be highly represented. Using FUMA, we found enrichment in Gene Ontology Cell Component for the synapse. Gene network analysis highlighted functions related to the cell cycle, nervous system development and function, and gene expression. No significant differences in age acceleration were found between Ex-Rp and N-Rp for any of the epigenetic clocks analysed. Our findings indicate that a specific methylation pattern could determine the response to Li in BD patients. We also found that a significant portion of the differentially methylated genes are closely associated with the GSK3β pathway, reinforcing the role of this system in Li response. Future longitudinal studies with larger samples will help to elucidate the epigenetic mechanisms underlying Li response.

Introducing the Role of Genotoxicity in Neurodegenerative Diseases and Neuropsychiatric Disorders

Decades of research have identified genetic and environmental factors involved in age-related neurodegenerative diseases and, to a lesser extent, neuropsychiatric disorders. Genomic instability, i.e., the loss of genome integrity, is a common feature among both neurodegenerative (mayo-trophic lateral sclerosis, Parkinson's disease, Alzheimer's disease) and psychiatric (schizophrenia, autism, bipolar depression) disorders. Genomic instability is associated with the accumulation of persistent DNA damage and the activation of DNA damage response (DDR) pathways, as well as pathologic neuronal cell loss or senescence. Typically, DDR signaling ensures that genomic and proteomic homeostasis are maintained in both dividing cells, including neural progenitors, and post-mitotic neurons. However, dysregulation of these protective responses, in part due to aging or environmental insults, contributes to the progressive development of neurodegenerative and/or psychiatric disorders. In this Special Issue, we introduce and highlight the overlap between neurodegenerative diseases and neuropsychiatric disorders, as well as the emerging clinical, genomic, and molecular evidence for the contributions of DNA damage and aberrant DNA repair. Our goal is to illuminate the importance of this subject to uncover possible treatment and prevention strategies for relevant devastating brain diseases.

Oxidation of DNA and RNA in young patients with newly diagnosed bipolar disorder and relatives

Excessive oxidative stress-generated nucleoside damage seems to play a key role in bipolar disorder (BD) and may present a trait phenomenon associated with familial risk and is one of the putative mechanisms explaining accelerated atherosclerosis and premature cardiovascular diseases (CVD) in younger patients with BD. However, oxidative stress-generated nucleoside damage has not been studied in young BD patients and their unaffected relatives (UR). Therefore, we compared oxidative stress-generated damage to DNA and RNA in young patients newly diagnosed with BD, UR, and healthy control individuals (HC). Systemic oxidative stress-generated DNA and RNA damage levels were compared by analyzing urinary levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydroguanosine in participants aged 15-25 years, including 133 patients newly diagnosed with BD, 57 UR, and 83 HC. Compared with HC, damage to DNA was 21.8% higher in BD patients (B = 1.218, 95% CI = 1.111-1.335, p = <0.001) and 22.5% higher in UR (B = 1.225, 95% CI = 1.090-1.377, p = <0.002), while damage to RNA was 14.8% higher in BD patients (B = 1.148, 95% CI = 1.082-1.219, p = <0.001) and 14.0% higher in UR (B = 1.140, 95% CI = 1.055-1.230, p = < 0.001) in models adjusted for sex and age after correction for multiple comparison. Levels did not differ between patients with BD and UR. Our findings support higher oxidative stress-generated nucleoside damage being a trait phenomenon in BD associated with familial risk and highlight the importance of early diagnosis and treatment to prevent illness progression and development of premature CVD.

A comparative meta-analysis of peripheral 8-hydroxy-2'-deoxyguanosine (8-OHdG) or 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) levels across mood episodes in bipolar disorder

OBJECTIVE

Oxidative DNA damage has been associated with the pathophysiology of bipolar disorder (BD) as one of the common pathways between increased medical comorbidity and premature aging in BD. Previous evidence shows increased levels of oxidatively induced DNA damage markers, 8-hydroxy-2'-deoxyguanosine (8-OHdG) or its tautomer 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), in patients with BD in comparison to healthy individuals. With the current research, we aim to analyze data on peripheral (blood or urine) 8-OHdG/8-oxo-dG levels across mood states of BD using a meta-analytical approach.

METHOD

A literature search was conducted using the databases PubMed, Scopus, and Web of Science to identify eligible studies (January 1989 to July 2022). Relevant studies were systematically reviewed; a random-effects meta-analysis and a meta-regression analysis were conducted.

RESULTS

The current meta-analysis included 12 studies consisting of 808 BD patients (390 in euthymia, 156 in mania, 137 in depression, 16 in mixed episode, 109 not specified) and 563 healthy controls. BD patients that were currently depressed had significantly higher levels of 8-OHdG/8-oxo-dG than healthy controls, while euthymic or manic patients did not differ from healthy controls. A meta-regression analysis showed sex distribution (being female) and older age to be significantly related to increased 8-OHdG/8-oxo-dG levels.

CONCLUSION

Our findings suggest that 8-OHdG/8-oxo-dG may be a state-related marker of depression in BD and may be affected by older age and female gender.